The Fundamental Unit of Life class 9 biology MCQ & SAQ

The Fundamental Unit of Life class 9 biology NCERT SOLUTION:

 

Q1. Who discovered cells and how?

Ans:

• The cell was first discovered by Robert Hooke in 1665. He examined thin slices of cork under a self-made microscope and saw a multitude of tiny hollow spaces that he remarked looked like the walled compartments of a honeycomb. 

• He termed these spaces as ‘cell’ meaning ‘small room’ in Latin.
  
  

Q2. Why is the cell called the structural and functional unit of life?

Ans:

• All living organisms are made up of cells. This shows that the cell is the structural unit of life. 

• Each living cell has the capacity to perform certain basic functions that are characteristics of all living forms.
  Example:
  (i) Phagocytic cells eat or kill unwanted or foreign particles inside the body (e.g., WBCs).
  (ii) Some cells secrete enzymes and hormones, e.g., pancreatic cells, small intestinal cells, liver cells.

Page No. 61

Q1. How do substances like CO2 and water move in and out of the cell? Discuss.

Ans: CO2 moves by diffusion – This cellular waste accumulates in high concentrations in the cell, whereas the concentration of CO2 in the external surroundings is comparatively lower. This difference in the concentration level inside and out of the cell causes the CO2 to diffuse from a region of higher(within the cell) to a lower concentration.

H2O diffuses by osmosis through the cell membrane. It moves from a region of higher concentration to a lower concentrated region through a selectively permeable membrane until equilibrium is reached.

 

Q2. Why is the plasma membrane called a selectively permeable membrane?

Ans: The plasma membrane allows or permits the entry and exit of some materials in and out of the cell and prevents the movement of some other materials through it. Hence, it is called a selectively permeable membrane.

 

 

 

 

 

 

 

 

 

 

 

 

 

Page No. 63

Q1. Fill in the gaps in the following table illustrating the differences between prokaryotic and eukaryotic cells.

Ans:

 

Page No. 65

Q1. Can you name the two organelles we have studied that contain their own genetic material?

Ans: Two organelles that contain their own genetic material are Mitochondria and Plastids.

 

Q2. If the organization of a cell is destroyed due to some physical or chemical influence, what will happen?

Ans:

• Cell organelles are responsible for the organization and proper functioning of a cell, as each of them performs some specific functions. 

• Naturally, if any of these organelles are destroyed, the functions of the cell will be stopped and it may also result in the death of the cell.

Q3. Why are lysosomes known as suicide bags?

Ans:

• Lysosomes are the cell organelles involved in the digestion of any foreign material that enters the cell as they contain digestive enzymes. 

• In case anybody's cell is dead or damaged, the lysosome bursts to release the digestive enzymes in order to digest its own cell. 

• Thus, these are known as ‘suicide bags’.

Q4. Where are proteins synthesized inside the cell?

Ans:

• Proteins are synthesized in ribosomes present in the cell and so they are also called protein factories of the cell. 

• These may be attached to the surface of the rough endoplasmic reticulum or lie freely in the cell.

Page No. 67

Q1. Make a comparison and write down ways in which plant cells are different from animal cells.

Ans:

 

Q2. How is a prokaryotic cell different from a eukaryotic cell?

Ans:

 

 

Q3. What would happen if the plasma membrane ruptures or breaks down?

Ans:

• The plasma membrane is the selectively permeable membrane that surrounds the cell and allows the entry and exit of selected materials of the cell. 

• If it ruptures, the contents of the cell will come in direct contact with the surrounding medium and not only unwanted material will be able to enter freely into the cell, but useful material will also find its way out of the cell easily. 

• This will seriously disrupt the various metabolic activities of the cell and will result in its imminent death.

Q4. What would happen to the life of a cell if there was no Golgi apparatus?

Ans:

• If there were no Golgi apparatus, the material synthesized by endoplasmic reticulum would not be carried to the various parts inside and outside of the cell.
  
  

• Also as the Golgi apparatus performs the function of storage and modification of the material synthesized in the cell, these materials would not be stored and modified further.

• Moreover, there will be no production of lysosomes which will cause the accumulation of waste material, viz., worn out and dead cell organelles within the cell which will ultimately lead to cell death.

Q5. Which organelle is known as the powerhouse of the cell? Why

Ans:

• Mitochondria are known as the powerhouse of the cell because these are the sites of cellular respiration.
  
  

• Mitochondria

•  

• They release energy in the form of ATP (Adenosine Triphosphate). This energy is then utilized by the organelles to carry out their basic functions.

Q6. Where do the lipids and proteins constituting the cell membrane get synthesized?

Ans:

• Lipids are synthesized in smooth endoplasmic reticulum from where they are transported to the cell membrane.

• Proteins are synthesized by the ribosomes in the cytoplasm. 

• These are then transferred to the Golgi complex and ER for further modifications from where they reach their destinations.

Q7. How does an Amoeba obtain its food?

Ans:

• Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particle forming a food-vacuole as shown in the figure. 

• Inside the food vacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm. 

• The remaining undigested material is moved to the surface of the cell and thrown out.
  
  

• Nutrition in Amoeba

•  

Q8. What is osmosis?

Ans: It is the passage of solvent from a region of high concentration to a region of low concentration through a semipermeable membrane.

 

Q9. Carry out the following osmosis experiment

Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,

(a) Keep cup A empty.

(b) Put one teaspoon sugar in cup B

(c) Put one teaspoon salt in cup C

(d) Put one teaspoon of sugar in the boiled potato cup D.

Keep these for two hours. Then observe the four potato cups and answer the following

(i) Explain why water gathers in the hollowed portion of B and C.

(ii) Why is potato A necessary for this experiment?

(iii) Explain why water does not gather in the hollowed out portions of A and D.

Ans: 

(i) 

• Water gathers in the hollowed portion of cups B and C because of the process of endosmosis (moving in of the solvent). The potato wall acts as a semipermeable membrane. 

• As cups B and C are filled with sugar and salt respectively and their outer part is in contact with the water, the concentration of water outside the cups is higher than inside the cups. 

• So, water moves from its higher concentration towards the lower concentration, i.e., inside the cup. 

(ii) Potato A is necessary for this experiment because:

• Potato A acts as a control of the experiment. It is very necessary for comparing the results of the experiment. 

• It shows that if the concentration of water is the same on both sides, there will be no movement of water. 

(iii) Water does not gather in the hollowed out portions of A and D because:

• Water does not gather in the hollowed out portions of A as it does not contain hypertonic solution so there is no concentration difference and hence no movement of solvent. 

• Water does not gather in cup D as the cells of boiled potato are dead and the potato wall is no longer semi-permeable. Hence, no osmosis occurs.

Q10. Which type of cell division is required for the growth and the repair of the body and which type is involved in formation of gametes?

Ans:

• For growth and repair, mitotic division (mitosis) is involved as this type of division keeps the chromosome number constant.

• For gamete formation, meiosis is involved as reduction of chromosome number is necessary for this case.

The Fundamental Unit of Life class 9 biology MCQ 

 

1. The process of plasmolysis in plant cell is defined as:

(a) Breakdown of plasma membrane in hypotonic solution.

(b) Shrinkage of cytoplasm in hypertonic medium.

(c) Shrinkage of Nucleoplasm.

(d) None of these

► (b) Shrinkage of cytoplasm in hypertonic medium.

2. The proteins and lipids, essential for building the cell membrane, are manufactured by

(a) rough endoplasmic reticulum

(b) Golgi apparatus

(c) plasma membrane

(d) mitochondria

► (a) rough endoplasmic reticulum

3. Engulfing of food materials or foreign bodies by cells like Amoeba is called

(a) diffusion

(b) endocytosis

(c) osmosis

(d) plasmolysis

► (b) endocytosis

4. Animal cell lacking nuclei would also lack in

(a) Endoplasmic reticulum

(b) Chromosome

(c) Lysosome

(d) Ribosome

► (b) Chromosome

5. Middle lamella occurs:

(a) Inner to primary wall

(b) Inner to secondary wall

(c) Outer to secondary wall

(d) Outer to primary wall

► (d) Outer to primary wall

6. A cell will swell up if

(a) the concentration of water molecules in the cell is higher than the concentration of water molecules in surrounding medium

(b) the concentration of water molecules in surrounding medium is higher than water molecules concentration in the cell

(c) the concentration of water molecules is same in the cell and in the surrounding medium

(d) concentration of water molecules does not matter

► (b) the concentration of water molecules in surrounding medium is higher than water molecules concentration in the cell

7. Cell wall is absent in

(a) Plants

(b) Bacteria

(c) Fungi

(d) Mycoplasma

► (d) Mycoplasma

8. Name two cell regions containing their own genetic material.

(a) Mitochondria and Plastids

(b) Lysosomes and ribosomes

(c) Nucleus and mitochondria

(d) Golgi apparatus and endoplasmic reticulum

► (a) Mitochondria and Plastids

9. Cartilage matrix is digested during its osteogenesis through:

(a) Intracellular autophagic activity

(b) Extracellular lysosomal activity

(c) Intracellular heterophasic activity

(d) Both B and C

► (b) Extracellular lysosomal activity

10. Nuclei were first discovered by

(a) Strasburger

(b) Fontana

(c) Robert Brown

(d) Robert Koch

► (c) Robert Brown

11. Which of the following is not a function of golgi apparatus?

(a) Detoxification of poisons and drugs

(b) Storage and packaging of products

(c) Formation of lysosomes

(d) Production of complex sugars

► (a) Detoxification of poisons and drugs

12. Ribosomes are the center for

(a) Respiration

(b) Proteins synthesis

(c) Photosynthesis

(d) Fat synthesis

► (b) Proteins synthesis

13. Golgi apparatus takes part in synthesis of:

(a) Glycolipids

(b) Glycoproteins

(c) Hormones

(d) All the above

► (d) All the above

14. Name the plastid important for photosynthesis in plants.

(a) Leucoplast

(b) Chromoplast

(c) Chloroplast

(d) Cytoplast

► (c) Chloroplast

15. In plant cells, many substances important for life are stored in

(a) plastids

(b) mitochondria

(c) vacuoles

(d) lysosomes

► (c) vacuoles

16. Which of the following is correct for prokaryotic ribosome:

(a) It dissociates into 50S and 30S

(b) It dissociates into 40S and 40S

(c) It dissociates into 60S and 20S

(d) It dissociates into 70S and 30S

► (a) It dissociates into 50S and 30S

17. In a cell DNA is found in:

(a) Nucleus, mitochondria and plastid

(b) Nucleus, mitochondria and Golgi body

(c) Mitochondria, Golgi body and plastid

(d) Nucleus, Golgi body and plastid

► (a) Nucleus, mitochondria and plastid

18. eRF1 is the release factor in eukaryotes that requires 

(a) ATP for its binding to ribosome

(b) GTP for its binding to ribosome

(c) ATP and GTP for its binding to ribosome

(d) Mn2+for its binding to ribosome

► (b) GTP for its binding to ribosome

19. The most abundant material in plant cell wall is

(a) cellulose

(b) lipids

(c) proteins

(d) wax

► (a) cellulose

20. Different layers of cell wall are:

(a) Middle lamella and primary wall

(b) Middle lamella, Primary wall and secondary wall

(c) Primary wall and secondary wall

(d) Wall layers exclude middle lamella

► (b) Middle lamella, Primary wall and secondary wall

21. Which organelle is called the suicide bag of the cell

(a) Golgi bodies

(b) Centrosome

(c) Chloroplast

(d) Lysosome

► (d) Lysosome

22. The primary function of smooth endoplasmic reticulum in liver cells is

(a) protein synthesis

(b) catabolism of proteins

(c) detoxification 

(d) carbohydrate metabolism

► (c) detoxification 

23. What is the full form of ATP?

(a) Adeno tri phosphate

(b) Adeno tri phosphorus

(c) Adenosine tetraphosphate

(d) Adenosine triphosphate

► (d) Adenosine triphosphate

24. Which of the following acts as a garbage disposal system of the cell?

(a) Golgi body

(b) Vacuole

(c) Peroxisome

(d) Lysosome

► (d) Lysosome

25. Which organelle is called power of house of the cell-

(a) Plastids

(b) Mitochondria

(c) Ribosomes

(d) Golgi apparatus

► (b) Mitochondria

26. Most of the substances in the living world are transported across the cell membrane by the process of

(a) osmosis

(b) endocytosis

(c) diffusion

(d) plasmolysis

► (a) osmosis

27.Animal cell lacking nuclei would also lack in

(a) Endoplasmic reticulum

(b) Chromosome

(c) Lysosome

(d) Ribosome

► (b) Chromosome

28. Find out the correct sentence. 

(a) Enzymes packed in lysosomes are made through RER

(b) Rough endoplasmic reticulum and smooth endoplasmic reticulum produce lipid and protein respectively

(c) Endoplasmic reticulum is related to the destruction of plasma membrane

(d) Nucleoid is present inside the nucleoplasm of eukaryotic nucleus

► (a) Enzymes packed in lysosomes are made through RER

The Fundamental Unit of Life class 9 biology SAQ

Question 1. What are plastids? Name the different types of plastids found in plant cells.Answer: Plastids are organelles found only in plants. They are:

(a) Chloroplast-Containing chlorophyll

(b) Chromoplast-Containing carotenoids and xanthophyll (coloured plastids)

(c) Leucoplast-Wllite or colorless plastids

Question 2. What is plasma membrane made up of?

Answer: Plasma membrane is made up of proteins and lipids.

Question 3. What did Robert Hooke observe first in a cork cell?

Answer: Robert Hooke observed that cork consists of box-like compartments which formed a honeycomb structure.

Question 4. Name the autonomous organelles in the cell.

Answer. Chloroplasts and mitochondria are the autonomous organelles in the cells.

Question.5. What does protoplasm refer to?

Answer: Protoplasm refers to cytoplasm and nucleus.

Question 6. Name two cells which keep changing their shape.

Answer: Amoeba and white blood cells.

Question 7. Name the smallest cell and the longest cell in the human body.

Answer: The smallest cell is the red blood cell or sperm cell in male. Longest cell is the nerve cell.

Question 8. Name 3 features seen/present in almost every cell.

Answer: Plasma membrane, nucleus and cytoplasm.

Question 9.What is diffusion?

Answer: When gasses like C02, 02, move across the cell membrane, this process is called diffusion.

Question 10.What is osmosis? This takes place from high water concentration to low water concentration.

Answer: The movement of water molecules through a selectively permeable membrane is called osmosis. This takes place from high water concentration to low water concentration.

Question 11. What is the full form of DNA?

Answer: DNA —> DeoxyriboNucleic Acid.

Question 12. What is the Junction of chromosomes?

Answer: Chromosomes contain information for the inheritance of features from parents to the next generation in the form of DNA molecules.

a) What is DNA ? Where is it found ?

(b) Name the functional segment of DNA. (CCE 2010, 2011)

Answer:

(a) DNA or deoxyribonucleic acid is genetic material of living beings. It occurs as part of chromatin in the nucleus and as such in mitochondria and plastids.

(b) Gene.

Name two similarities between mitochondria and plastids.

(CCE 2010, 2011)

Answer:

Both of them possess

1. Double membrane covering

2. Their own DNA.

Question 3.

Mention any two functions of endoplasmic reticulum.

(CCE 2010, 2011, 2013)

Answer:

1. Biosynthesis: Endoplasmic reticulum is engaged in synthesis of lipids (SER) and proteins (RER).

2. Support: It provides support to cytoplasm.

Question 4.

Give function of the following organelles

1. Chloroplast

2. Nucleus

3. Ribosomes. (CCE 2010, 2011, 2012)

Answer:

1. Chloroplast: Photosynthesis,

2. Nucleus: Control of cellular activities and inheritance

3. Ribosomes: Protein synthesis.

Question 5.

State cell theory. Name the scientist who presented it. (CCE 2010)

Answer:

Cell theory states that cells are the structural and functional units of bodies of all living beings. The theory was put forward by Schleiden and Schwann ( 1839).

Question 6.

What is plasmolysis ? Give one example. (CCE 2010, 2011)

Answer:

Plasmolysis is shrinkage of protoplasm from the cell wall due to continued exosmosis when cells are placed in hypertonic solution. A peeled carrot piece placed in salt solution will contract due to plasmolysis of its cells.

Question 7.

Write the names of two cell organelles that have their own DNA and ribosomes. (CCE 2010)

Answer:

1. Plastids

2. Mitochondria.

Question 8.

What is endocytosis ? Name an organism that feeds by this method. (CCE 2010, 2011, 2013)

Answer:

Endocytosis is the bulk transfer of materials from outside to inside of a cell with the help of special vesicles developed by plasma membranes. Organism (that feeds by endocytosis). Amoeba.

Question 9.

(a) What is plasma membrane made up of ?

(b) Name the process and also explain how food and other substances enter through the plasma membrane. (CCE 2010)

Answer:

(a) Plasma membrane is made of a bilayer of lipids (or phospholipids) and proteins located inside and outside the same,

(b) Food passes through the plasma membrane by endocytosis. Other bulk transports also occur through it. For soluble substances, plasma membrane shows selective permeability.

Question 10.

Two Rhoeo peels were taken. One peel was put in a petri dish containing cold water and the other was put in a petri dish containing hot water. After a while both were transferred to hypertonic solutions. If the peels were observed under the microscope, will there be any difference in the observation of both the peels? Yes or no. Give reason for your answer.

(CCE 2010)

Answer:

Yes. There is a difference. The peel placed initially in hot water does not undergo plasmolysis. Plasmolysis occurs in cells of the peel initially kept in cold water. Hot water kills the cells. Dead cells do not show osmosis.

Question 11.

Give a technical term for a medium which has exactly the same concentration as the cell ? Why does the size of the cell remain the same when placed in such a solution ?  (CCE 2010)

Answer:

Isotonic solution. A cell placed in an isotonic solution neither gains water nor loses water as equal amounts of water pass inwardly and outwardly in it.

Question 12.

Mention two functions of Golgi apparatus. (CCE 2011)

Answer:

1. Formation of complex sugars,

2. Formation of lysosomes.

3. Storage, modification and packaging of various substances,

4. Secretion and excretion.

Question 13.

How do substances like CO2 and water move in and out of a cell? (CCE 2011)

Answer:

CO2 moves into and out of the cell through diffusion or passage from the area of its higher concentration to the area of its lower concentration across the cell membrane.

Water moves into and out of the cell through osmosis or passage of water from the area of higher concentration (e.g., dilute solution) to the area of lower concentration (e.g., strong solution) across the cell membrane which acts as a semipermeable membrane.

Question 14.

(a) In which form does mitochondria release energy ? Write its full form.

(b) The inner membrane of mitochondria is deeply folded. What is the advantage of these folds ? (CCE 2011, 2012)

Answer:

(a) As ATP or adenosine triphosphate.

(b) Folding of the inner membrane creates a large surface area for ATP generating reactions.

Question 15.

Where are chromosomes located in a cell ? What are they composed of ? What important information do they contain ? (CCE 2011)

Answer:

Location: Nucleus.

Composition: DNA and proteins.

Information: They carry genetic information for structural and functional traits in the form of genes.

Question 16.

Preetha was observing live cells of Onions in the biology laboratory. She observed the cell wall, cytoplasm and nucleus clearly. Suddenly her friend who was doing a chemistry experiment spilled a few drops of salt water on the slide. After some time Preetha observed the slide and found some changes,

(a) What would have been the change in the live cells of Onion peel after adding salt water ?

(b) Name the type of process.

(CCE 2011)

Answer:

(a) There was shrinkage of cytoplasm away from the cell wall.

(b) Plasmolysis.

Question 17.

How can plant cells withstand much greater changes in the surrounding medium than the animal cells ?

(CCE 2011)

Answer:

Plant cells are covered by a rigid wall. The cell wall allows the plant cells to withstand changes in the surrounding medium better than animal cells.

Question 18.

Write two characteristics of prokaryotic cells. (CCE 2011)

Answer:

(i) Genetic material is equal to a single chromosome which is not organized into a nucleus,

(ii) Membrane bound cell organelles absent.

Question 19.

What are unicellular organisms ? List two examples. (CCE 2011)

Answer:

Organisms made of single cells are called unicellular organisms. Examples. Amoeba, Paramoecium.

Question 20.

Which stain is used to prepare an Onion peel slide ? Why do we need a stain to be added ? (CCE 2013)

Answer:

Safranin. The stain is added to make the cellular components clearly visible under the microscope.

Question 21.

Name the process by which

(a) Oxygen moves in and out of the cell,

(b) Water moves in and out of the cell. Differentiate between the two processes. (CCE 2013)

Answer:

(a) Diffusion

(b) Osmosis.

Question 22.

What will happen if

(a) Almonds are soaked in water.

(b) Concentrated solution of fertilizer is applied to green grass lawn. Give a suitable reason in support of your answer.

(CCE 2013)

Answer:

(a) Almonds will swell up due to endosmosis. There is a higher concentration of water around almonds than inside them.

(b) Grass will shrivel due to exosmosis. There is higher concentration of water inside grass plants than in outer concentrated fertilizer solution.

Question 23.

Give one function each of RER and SER. (CCE 2014)

Answer:

Function of RER. Synthesis of protein for export to Golgi apparatus.

Function of SER. Synthesis of lipids.

Question 24.

Name a cell organelle which lacks membrane. Where is it prepared ? (CCE 2014)

Answer:

(i) Ribosome,

(ii) It is synthesized in the form of subunits in the nucleolus part of the nucleus.

Question 25.

Differentiate between eukaryotic and prokaryotic cells, based on the size and number of chromosomes. (CCE 2014)

Answer:

The genetic material of a prokaryotic cell is equal to a small histone free chromosome and is often called prochromosome. A eukaryotic cell has two to several histone supported larger chromosomes.

Question 26.

What is the importance of osmosis in :

(a) Unicellular organisms

(b) Plants ? (CCE 2015)

Answer:

Osmosis in Unicellular Organisms. Absorption of water, osmoregulation.

Osmosis in Plants. Absorption of water from soil, cell to cell movement of water.

Question 27.

Which cell organelle is known as “suicide bags” of the cell ? Why? (CCE 2015)

Answer:

Lysosomes contain digestive enzymes against all types of organic materials. If their covering membrane breaks as it happens during injury to the cell, the digestive enzymes will spill over the cell contents and digest the same. As lysosomes are organelles which on bursting can kill the cells possessing them, they are called suicide bags.

Question 28.

Describe the structure of mitochondria with reference to its membrane covering. (CCE 2015)

Answer:

Structure: Mitochondria are rod or sausage shaped colorless organelles of aerobic eukaryotes that have a double membrane covering. The outer membrane is porous. The inner membrane is folded. The folds are called cristae. They bear ATP generating elementary particles. The matrix contains enzymes of Krebs cycle,

Question 29.

(a) Name the cell organelle which helps in packaging and

dispatching the material synthesized over the endoplasmic reticulum to various targets inside and outside the cell.

(b) Name and write function of cell organelle formed by the above cell organelle. ( CCE 2016)

Answer:

(a) Golgi apparatus,

(b) Lysosome: Lysosomes possess digestive enzymes which help in intracellular digestion and removal of senescent cellular structures.

Write in a tabular form three differences between a plant cell and an animal cell. (CCE 2010, 2011, 2012)

Answer:

Question 2.

Classify the following as osmosis or diffusion :

(a) Aquatic animals using oxygen dissolved in water during respiration.

(b) Swelling up of raisins on keeping in water.

(c) Spreading of virus on sneezing. (CCE 2010)

Answer:

(a) Diffusion

(b) Osmosis (endosmosis)

(c) Diffusion.

Question 3.

(a) Which cell organelles are called power houses of the cell and why ? (CCE 2010, 2012)

(b) Why is ATP called the energy currency of the cell ? (CCE 2010)

Answer:

(a) Mitochondria is known as powerhouse of the cell because it produces most of the molecules of ATP (adenosine triphosphate) which are required for providing energy for synthesis of new chemicals, mechanical and other cellular functions.

(b) ATP or adenosine triphosphate is called energy currency of the cell as it is built up when energy is available as from an * exothermic reaction and broken down to release the energy wherever required for performing an activity or an endothermic reaction.

Question 4.

Draw a neat diagram of an animal cell and label on it the following :

Plasma membrane. Nucleus, Lysosome/RER, centriole, Lysosome. (CCE 2010, 2012)

Answer:

Question 5.

List any three functions performed by endoplasmic reticulum.

(CCE 2010)

Answer:

1. Biosynthesis: Endoplasmic reticulum is engaged in synthesis of lipids (SER) and proteins (RER).

2. Support: It provides support to cytoplasm.

3. Transport: It helps in intracellular as well as intercellular transport of substances.

Question 6.

1. State two types of plastids

2. Write one function of each. (CCE 2010)

Answer:

1. Chloroplasts and chromoplasts.

2. Chloroplasts. Photosynthesis. Chromoplasts. Providing colouration to flowers and fruits for attracting animals to perform pollination and dispersal respectively.

Question 7.

What are chromosomes ? List their two functions.  (CCE 2010)

Answer:

Chromosomes are rod-like DNA containing stainable condensed chromatin units which become visible at the time of cell division.

Functions: 

1. They carry genetic information in the form of genes arranged in a linear sequence.

2. By their replication just before cell division and equitable distribution during cell division, chromosomes maintain the hereditary content of the cells.

Question 8.

List three differences between prokaryotic and eukaryotic cells. (CCE 2010, 2011, 2012)

Answer:

Question 9.

Describe the role played by lysosomes. Why are these termed as suicide bags ? How do they perform their function ?

(CCE 2011, 2012)

Answer:

Role: Lysosomes take part in

1. Destruction of foreign particles.

2. Intracellular digestion of food

3. Digestion and removal of worn out cell organelles.

Suicide Bags: Lysosomes contain digestive enzymes against all types of organic materials. If their covering membrane breaks as it happens during injury to the cell, the digestive enzymes will spill over the cell contents and digest the same. As lysosomes are organelles which on bursting can kill the cells possessing them, they are called suicide bags.

Working: Lysosomes are full of digestive enzymes. They fuse with foreign and worn out cell structures. Lysosomal enzymes bring about their digestion. The digested substances diffuse out into the cell while the undigested materials are thrown out of the cell.

Question 10.

Explain your observation in the following with reason involved in the process : (a) Salt is applied to raw mango pieces (b) Dried raisins are kept in water for a few hours.

(CCE 2011)

Answer:

(a) Salt applied over raw mango pieces will kill the surface cells and prevent growth of microbes over them due to exosmosis.

(b) Raisins swell up due to endosmosis or entry of water into their cells due to osmosis.

Question 11.

Differentiate between diffusion and osmosis. Write any two examples where a living organism uses osmosis to absorb water. (CCE 2011, 2012)

Answer:

(a)

(b) Examples :

(i) Absorption of soil water by roots.

(ii) Gaining of water by guard cells during opening of stomata.

Question 12.

(a) Name the organelles which provide turgidity to the plant cell. Name any two substances which are present in it.

(b) How are they useful in unicellular organisms like Amoeba ?

(CCE 2011, 2014)

Answer:

(a) Vacuoles.

1. Water,

2. Dissolved storage and waste substances (Sugars, salts, amino acids, organic acids).

(b) In unicellular organisms vacuoles take part in

1. Osmoregulation and excretion by contractile vacuoles,

2. Digestion of food in food vacuoles.

Question 13.

Distinguish amongst hypotonic, isotonic and hypertonic solutions. (CCE 2011)

Answer:

Hypotonic solution has lower osmotic concentration and higher water concentration as compared to the cell. The cell gains water from Such external solutions by osmosis. Isotonic solution is the one which has the same osmotic concentration and water concentration as that of the cell. The cell placed in such a solution will neither gain nor lose water.

Hypertonic solution has a higher osmotic concentration and lower water concentration as compared to the cell. The cell loses water to such an external solution and gets plasmolysed.

Question 14.

(a) What is osmosis ?

(b) What happens to a cell when it is placed in hypotonic, isotonic and hypertonic solutions respectively ?

(c) What is plasmolysis ? (CCE 2011)

Answer:

(a) Osmosis is diffusion of water from the region of its higher concentration (pure water or dilute solution) to the region of its lower concentration (strong solution) through a semipermeable membrane.

(b)

1. Cell in Hypotonic Solution. Swells up due to endosmosis and becomes turgid.

2. Cell in Isotonic Solution. No change.

3. Cell in Hypertonic Solution. Cell contents shrink due to exosmosis or outward passage of water.

(c) Plasmolysis is shrinkage of protoplasm from the cell wall due to continued exosmosis when cells are placed in hypertonic solution. A peeled carrot piece placed in salt solution will contract due to plasmolysis of its cells.

Question 15.

State main functions of the following :

(a) Mitochondria

(b) Golgi apparatus

(c) Vacuoles. (CCE 2011)

Answer:

(a) Mitochondria,

1. Site of aerobic respiration.

2. Liberation of energy as ATP (hence powerhouse of cells).

(b) Golgi Apparatus.

1. Formation of lysosomes.

2. Complexing, packaging, secretion and excretion of substances.

(c) Vacuoles,

1. Storage of inorganic and organic substances.

2. Dumping of wastes.

3. Developing osmotic concentration for absorption of water and maintenance of turgidity of cells.

Question 16.

Briefly explain the structure and function of the nucleus.

(CCE 2011)

Answer:

Structure: Nucleus is oval or rounded dense cellular structure having four components :

1. A double membrane porous envelope (nuclear envelope),

2. Nuclear sap or nucleoplasm.

3. Chromatin made of threads of DNA and protein which get converted into chromosomes at the time of cell division,

4. Nucleolus, a rounded naked structure attached to chromatin and seat of ribosome formation.

Functions:

1. Nucleus controls cellular activities.

2. It contains genetic or hereditary information over its chromosomes for expression of various traits.

3. Ribosomes are formed in its nucleolus.

Question 17.

What are the two types of endoplasmic reticulum ? Mention one function of each. (CCE 2011)

Answer:

Types: There are two types of endoplasmic reticulum, smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). Rough endoplasmic reticulum bears ribosomes on its surface. The same is absent over SER.

Function of RER: Synthesis of proteins over its ribosomes.

Function of SER: Synthesis of lipids and steroids.

Question 18.

What are chromoplasts and leucoplasts ? Give an example of chromoplasts which have green pigment. ( CCE 2011)

Answer:

Chromoplasts. The coloured plastids are called chromoplasts. Leucoplasts. The colorless plastids are known as leucoplasts. Green Chromoplasts. Chloroplasts.

Question 19.

What will happen if the organization of a cell is destroyed due to some physical or chemical influence ? (CCE 2011)

Answer:

Organization is important for performing different functions of the cell. If the organisation is destroyed, the cell will not be able to perform many of its functions. This will lead to senescence and death of the cell Bursting of lysosomes will quicken death of the cell.

Question 20.

Draw the diagram to show animal cell and label the following parts :

(a) Powerhouse of the cell,

(b) Suicidal bag

(c) Organelle which helps in protein synthesis

(d) Organelle which helps during cell division.

(CCE 2011, 2012)

Answer:

(a) Mitochondrion

(b) Lysosome

(c) Ribosome

(d) Centriole.

Question 21.

(a) State two types of plastids. Mention the function of each.

(b) How do vacuoles help in ingestion and egestion in single celled organisms ? (CCE 2011, 2012)

Answer:

(a) Leucoplasts and chromoplasts. Leucoplast. Storage of carbohydrates, proteins and fats. Chromoplast. Photosynthesis by chloroplasts (green chromoplasts) and attractive colouration in flowers and fruits by non-green chromoplasts.

(b) During ingestion of food, the plasma membrane invaginates in contact with food particles and pinches off as small food containing vacuole called phagosome. Phagosome fuses with lysosome to form food vacuole. Digestion occurs. The digested materials pass out into cytoplasm. The vacuole containing undigested food pieces rises to the surface, fuses with plasma membrane to perform egestion.

Question 22.

What is the relationship between chromatin material and chromosomes ? (CCE 2011, 2013)

Answer:

Chromatin is an intertwined mass of thread-like DNA- protein complex that occurs in the nucleus. At the time of cell division, chromatin condenses and gets organized into chromosomes.

Question 23.

(a) Explain the phenomenon of plasmolysis.

(b) Explain how cell walls permit cells of fungi to withstand very dilute external media without bursting.

(CCE 2011)

Answer:

(a) Plasmolysis is shrinkage of protoplasm from the cell wall due to continued exosmosis when cells are placed in hypertonic solution. A peeled carrot piece placed in salt solution will contract due to plasmolysis of its cells.

(b) Despite being present in a very dilute medium, the fungal cells do not undergo unlimited swelling. Swelling stops as soon as the limit of cell wall elasticity is reached. At this time, the cell wall exerts an opposite force that prevents further entry of water.

Question 24.

List the specific functions of the following :

1. Rough endoplasmic reticulum

2. Golgi apparatus

3. Lysosomes

4. Mitochondria

5. Plastids

6. Vacuoles in unicellular organisms. (CCE 2011)

Answer:

Rough Endoplasmic Reticulum.

1. Protein synthesis,

2. Golgi Apparatus.

1. Formation of lysosomes.

2. Complexing, packaging, secretion and excretion of substances.

3. Lysosomes. Waste disposal, intracellular digestion,

4. Mitochondria,

1. Site of aerobic respiration.

2. Liberation of energy as ATP (hence powerhouse of cells).

5. Plastids Photosynthesis (chloroplasts), storage (leucoplasts), colouration (non-green chromoplasts).

6. Vacuoles in Unicellular Organisms. Osmoregulation, excretion, ingestion, digestion and egestion.

Question 25.

Describe the structure and write any two functions of Golgi apparatus. (CCE 2011)

Answer:

Golgi apparatus is a stack of curved membrane bound flat sacs called cisternae/cisterns that bear tubules and vesicles on the sides Functions.

Golgi Apparatus:

(a) Formation of lysosomes.

(b) Complexing, packaging, secretion and excretion of substances.

Question 26.

(a) Which organelles supply energy to a cell ? In what form is it stored ?

(b) Explain the structure of this organelle,

(c) Do these organelles contain DNA ? Why ? (CCE 2011)

Answer:

(a) Mitochondria. The energy is stored in the form of ATP.

(b) Structure. Mitochondria are rod or sausage shaped colorless organelles of aerobic eukaryotes that have a double membrane covering. The outer membrane is porous. The inner membrane is folded. The folds are called cristae. They bear ATP generating elementary particles. The matrix contains enzymes of Krebs cycle,

(c) Mitochondria possess DNA and ribosomes which help them in synthesis of a number of proteins for their functioning.

Question 27.

Mention the difference between prokaryotic and eukaryotic cells regarding

(i) Nuclear region

(ii) Cell organelles

(iii) Chlorophyll. (CCE2012)

Answer:

Question 28.

(a) What is membrane biogenesis ?

(b) Explain what happens when a drop of concentrated sugar solution is placed on a rheo leaf mounted on a glass slide. Name this phenomenon. Would the same happen if riyo leaf was boiled before mounting ? Give reason for your answer. (CCE 2012)

Answer:

(a) Membrane Biogenesis. It is the formation, renewal and repair of biomembrane from its constituents (lipids and proteins) synthesized over smooth and rough endoplasmic membrane and their modification by Golgi apparatus.

(b)

1. A concentrated sugar solution will cause exosmosis in cells of rheo peel mounted on a glass slide. The cytoplasm withdraws from the cell wall. The phenomenon is called plasmolysis.

2. Plasmolysis does not occur in cells of rhoeo leaf peel if the latter has been boiled before mounting. It is because boiling kills the cells. Exosmosis can occur only in living cells.

Question 29.

(a) Which cell organelle would you associate with ATP production ? How is this organelle able to make its own protein ?

(ib) A student performed an experiment by placing a de- shelled egg in a concentrated salt solution for five minutes.

What change did he observe in the egg ? Give reason for the same. (CCE 2012)

Answer:

(a) Mitochondrion. The organelle is able to synthesize some of its proteins because it has its own DNA and ribosomes.

(b) The de shelled egg placed in salt solution contracts. The contraction is caused by exosmosis.

Question 30.

(a) Where are genes located in a cell ?

(b) Name the nucleic acids that are present in animal cells. (CCE 2012)

Answer:

(a) Genes are located in the chromatin/chromosomes inside the nucleus.

(b) Animal cells has two types of nucleic acids, DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). While RNA is mostly located in the cytoplasm, DNA is present inside the nucleus (smaller quantity in mitochondria).

Question 31.

(a) State and explain the process by which Amoeba obtains its food. (CCE 2012)

(b) Why is the plasma membrane called a selectively permeable membrane ? (CCE 2012)

Answer:

(a) Amoeba obtains its food through endocytosis. Part of plasma membrane coming in contact with food particle

invaginates, engulfs the same and is pinched off into cytoplasm as phagosome. Phagosome fuses with a lysosome to produce a food vacuole. Digestion occurs in the food vacuole. The digested materials pass out into the cytoplasm. The vacuole having undigested matter rises to the surface and performs exocytosis to throw out the undigested matter.

(b) Cell membrane is a semipermeable membrane for water. It permits the entry of gasses through diffusion. Ions, sugar, amino acids, etc. pass through the plasma membrane by an active process. Plasma membrane is impermeable to certain other materials. Therefore, it is selectively permeable.

Question 32.

Two beakers A and B contain plain water and concentrated sugar solution respectively. Equal number of dried raisins are kept in them for a few hours and then taken out. (t) Explain the reason for the difference in the physical appearance of raisins which were taken out of the two beakers, (it) On the basis of above observation, categorize the two solutions as hypotonic and hypertonic. (CCE 2012)

Answer:

1. Raisins placed in beaker A have swollen while those of beaker B remain shriveled,

2. Solution (here water) in beaker A is hypotonic (as it causes entry of water into raisins) while solution in beaker B is hypertonic as no water from this solution passes into raisins.

Question 33.

(a) How is the flexible nature of plasma membranes useful to Amoeba? Name the process.

(b) Plastids are able to make their own protein. Explain.

(c) Why plant cells shrink when kept in hypertonic solution.

(CCE 2012)

Answer:

(a)Flexible nature of plasma membrane is useful to Amoeba in

1. Engulfing food particles. The process is called endocytosis.

2. Formation of pseudopodia for locomotion.

(b) Plastids possess DNA and ribosomes for formation of proteins as per information present in the former.

(c) Plant cells placed in hypertonic solution shrink due to passage of a part of their contained water into outer solution due to exosmosis.

Question 34.

(a) List two roles of nucleus of a cell,

(b) Name two substances stored in the vacuoles of a plant cell.

(CCE 2012)

Answer:

(a) Roles of Nucleus,

1. Control: Nucleus controls cell metabolism and cell activities,

2. Hereditary Information: Nucleus contains all the hereditary information not only for the cell but also the whole organism.

(b) Substances in Vacuoles,

1. Water

2. Salts and some organic substances.

Question 35.

(a) Who gave the term Golgi apparatus,

(b) Name one cell organelle formed by Golgi apparatus.

(c) Write any two functions of Golgi apparatus.

Answer:

(a) Cajal (1914).

(b) Lysosome

(c)

(i) Complexing, packages, secretion and excretion of substances,

(ii) Membrane biosynthesis.

Question 36.

Distinguish leucoplast from chromoplast based on one feature. Give an example of chromoplast present in plant cells. What is the function of chromoplast in a plant cell ?

(CCE 2012)

Answer:

Leucoplast is colorless plastid while chromoplast is coloured plastid. Chromoplast present in green aerial cells of the plant is called chloroplast. It takes part in photosynthesis.

Question 37.

Differentiate between rough and smooth endoplasmic reticulum. How is endoplasmic reticulum important for membrane biosynthesis ? (CCE 2012)

Answer:

Rough endoplasmic reticulum bears ribosomes over its surfaces while the same are absent over smooth endoplasmic reticulum. The two types of endoplasmic reticulum synthesize proteins and lipids that are modified and complexed by Golgi apparatus for membrane biosynthesis.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Question 13. Name the organelles present in the liver of animals for detoxifying many poisons and drugs. 

Answer: In the liver of animal cells smooth endoplasmic reticulum helps in detoxifying many poisons and drugs.

Question 14. What is the energy currency of the cell?

Answer: ATP—Adenosine Triphosphate.

Question 15. What is the function of the ribosome?

Answer: Ribosomes help in protein synthesis.

Question 16. Where are genes located in the cell?

Answer: Genes are located in the chromosomes in the nucleus of the cell.

Question 17. Name the cell organelles that help in packaging?

Answer: Golgi apparatus.

Question 18. Name the cell organelle which helps in the transportation of material.

Answer: Endoplasmic reticulum.

Question 19. Name the cell organelle due to which leaves, flowers and fruits get their color.

Answer: Chromoplast.

Question 20. Name the cell organelle which helps in the formation of lysosomes.

Answer: Golgi apparatus.

Question 21. Name the cleansing organelle in the cell.

Answer: Lysosomes.

Question 22. Name two cells with a cell wall.

Answer: Onion cell (plant cell) and fungi.

Question 23. Why do mitochondria have a largely folded inner membrane?

Answer: Mitochondria is the site for cellular respiration and provides energy to the cell. The largely folded inner membrane provides the increased surface area for ATP-generating chemical reactions.

Question 24. Which organelle makes the digestive enzyme of lysosome?

Answer: Rough endoplasmic reticulum makes the digestive enzyme of lysosomes.

Question 25. What are cisterns?

Answer: The golgi bodies consist Of a system of membrane-bound vesicles arranged in stacks called cisterns.

Question 1. State two conditions required for osmosis.

Answer: (i) The difference in the concentration of water, one should have higher concentration than the other.

(ii) Semi-permeable membrane is also required through which water will flow.

Question 2. What is plasmolysis?

Answer: When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.

Question 3. How do fungi and bacteria can withstand much greater changes in the surrounding medium than animal cells?

Answer: The cell wall present in fungi and bacteria permits these cells to withstand a very dilute external medium without bursting.

The cells take up water by osmosis, swells, and builds the pressure against the cell wall. The wall exerts an equal pressure against the swollen cell. It is because of the cell wall, such cells can withstand much greater changes in the surrounding medium than animal cells.

Question 4. Give the function of the nuclear membrane.

Answer: The nuclear membrane present as outer covering in the nucleus allows the transfer of material inside and out of the nucleus to cytoplasm.

Question 5. Name the cell-organelles that have their own DNA and ribosomes.

Answer: The cell organelles with their own DNA and ribosomes are mitochondria and plastids.

Question 6. State the difference between smooth endoplasmic reticulum and rough endoplasmic reticulum.

Answer:

Question 7. What is endocytosis?

Answer: The cell membrane's flexibility allows the cell to be engulfed in food and other material from its external environment. This process is known as endocytosis. E.g., Amoeba acquires its food through such processes.

Question 8. What is the function of vacuoles?

Answer: Vacuoles are storage sacs for solid or liquid content. In plant cells it provides turgidity and rigidity to the cell. In single-celled organisms vacuoles store food, e.g., Amoeba.

Question 9. When we put raisins in water, why do they swell?

Answer: Raisins are dry with less water inside, when they are kept in water, osmosis takes place, water flows through the cell wall, cell membrane of the raisins and therefore it swells.

Question 10. Why are lysosomes called suicidal bags?

Answer: Lysosomes contain digestive enzymes in it and help in the cleaning of cells by digesting any foreign materials entering the cell, such as bacteria, food and old cell organelles.

When the lysosomes burst, the digestive enzyme digests its own cell. Hence it is called as suicidal bag.

Question 11. What is a nucleoid?

Answer: The nuclear region in some cells is poorly defined due to the absence of a nuclear membrane, it contains only nucleic acid. This undefined nuclear region with nucleic acid in it is called nucleoid.

Question 12. What is the role of cell organelles in the cell?

Answer: Each kind of cell organelles performs a specific function such as making new material, clearing of the waste, transporting material, etc.

Question 13. Label the figure and answer the questions:

(i) A – It is the packaging organelle

(ii) B – Provides energy

(iii) C – helps in the transport of material

(iv) D – Carries the information.

Answer. (i) A – Golgi body (ii) B – Mitochondria

(iii) C – Endoplasmic reticulum (iv) D – Nucleus

Question 14. What is the function of the nucleus in a cell?

Answer: The nucleus plays a very important role in the reproduction of cells. It also helps the single cell to divide and form two new daughter cells.

It plays an important role in determining how the cell will develop and what form it will exhibit at maturity, by directing the chemical activities of the cell.

Question 15. What is the Junction of plastids?

Answer: Plastids are present only in plant cells. There are two types of plastids chromoplasts (coloured plastids) and leucoplasts (white or colorless)

Chromoplast—Consists of coloured pigments and gives different colors to flowers, fruits and leaves. The green color pigment present in leaf is called chlorophyll which helps in the photosynthesis and a plastid with chlorophyll is called chloroplast.

Leucoplast—It stores starch, oil and protein granules in it.

Question 16. Do vacuoles store some material? If yes, name them.

Answer: Yes, vacuoles also store some important substances required in the life of the plant cell. These are amino acids, sugars, various organic acids and some proteins. In some unicellular organisms, e.g. Amoeba, vacuoles also store food.

Question 17. Explain the structure and function of Golgi bodies.

Answer: Structures: Golgi bodies consist of a system of membrane-bound vesicles arranged in stacks parallel to each other called cisterns. These membranes have connections with the membrane of endoplasmic reticulum (ER).

Functions:

(1) The material synthesized near the ER is packaged and dispatched to various targets inside and outside the cell through Golgi apparatus.

(2) It also stores, modifies and helps in the packaging of products in vesicles.

(3) In some cases, complex sugars may be made from simple sugars in it.

(4) It also helps in the formation of lysosomes.

Question 18. What are ribosomes? Where are they located in the cell? What is their function?

Answer: Ribosomes are spherical organelles present in the cell which are either freely distributed in the cytoplasm or may be attached to the endoplasmic reticulum.

It consists of ribosomal RNA (Ribonucleic acid) and proteins.

Functions of Ribosomes: It helps in the synthesis of proteins.

Question 19. What is the difference in chromatin, chromosomes and genes?

Answer: (1) Chromatin: It is a fine network of thread-like structure made up of DNA or RNA. It gets condense to form chromosomes.

(2) Chromosome: The chromosomes are made from chromatin material and are located in the cell.

(3) Genes are found in chromosomes.

Question 20. Why do plant cells have more in number and big-sized vacuoles as compared to the animal cells?

Answer: Plant cells attain turgidity and rigidity due to the more number of vacuoles as well as large-sized vacuoles help the plant cells to withstand the wear and tear, external environmental conditions.

They also help in the storage of essential material required by plants for their growth like amino acids, sugar and various organic substances.

Question 21. Explain the following terms:

(a) Plasma membrane

(b) Cytoplasm

(c) Nucleus.

Answer: (a) Plasma membrane: It is a thin membrane which controls the passage of materials in and out of the cell. It is also called a selectively permeable membrane. It makes the outer boundary of the cell and is made up of lipo-protein,

(b) Cytoplasm: It is a transparent jelly-like thick substance present in the cell. It makes the ground of the cell in which all the cell organelles are suspended.

(c) Nucleus: It is a double-layered membrane structure which contains chromosomes required for the inheritance of characteristics from one generation to the other.

Question 22. What is membrane biogenesis?

Answer: The endoplasmic reticulum helps in the manufacture of proteins and fat molecules or lipids which are important for the cell function. These proteins and lipids help in the building of the cell membrane. This process is known as membrane biogenesis.

Question 23. Which organelle is known as the powerhouse of the cell?

Answer: Mitochondria is known as the powerhouse of the cell because they store energy in the form of ATP. [Adenosine Triphosphate]

Question 24. What are genes?

Answer: Gene is a segment of DNA. They are located on chromosomes in linear fashions. One gene may perform one or more functions. Genes are carriers of genetic codes.

Question 25. Draw various cells of the human body.

Answer:

The Fundamental Unit of Life class 9 biology LONG QUESTION:

Question 1. Give five points of differences between plant cells and animal cells.

Answer:

 

Question 2. Give five points of differences between prokaryotic cell and eukaryotic cell.

Answer:

 

Question 3. Draw a neat labeled diagram of the plant cell and label its parts.

Answer:

Question 4. Draw a neat labeled diagram of animal cells.

Answer:

Question 5. Name the cell organelle for the following:

(a) Present only in the plant cell, providing strength and rigidity to the cell.

(b) It is the site for lipids synthesis and helps in detoxification of drugs.

(c) The inner membrane is folded to form cristae, it has its own DNA and proteins.

(d) It helps in the formation of lysosomes.

(e) It imparts color to the fruit and flowers.

Answer: (a) Cell wall

(b) Smooth endoplasmic reticulum

(c) Mitochondria

(d) Golgi apparatus

(e) Chromoplast

 

Question 1. Vasu was helping his mother in laying the table when they had some guests for dinner. Vasu was about to sprinkle salt on salad for dressing. His mother stopped him from doing so and told him that it is too early to sprinkle salt on the salad, he should do so only when they are seated for having dinner.

(a) What would happen if salt is sprinkled on the salad?

(b) Which property of cells is seen in adding salt to it?

(c) What value of Vasu is seen?

Answer: (a) On sprinkling some salt on the salad, the salad will release water.

(b) The salt outside the salad acts as a hypertonic solution as it has less water concentration and therefore the cell loses water by osmosis.

(c) Vasu showed the value of being very helpful, caring and responsible.

Question 2. Anu is a five year old girl who joined the swimming classes. After the first class she was worried when she saw her wrinkled fingers. She asked her elder sister about the wrinkling and shrinking of her fingers. Her sister explained to Anu why it was so.

(a) Why did the fingers wrinkle after swimming?

(b) What caused the shrinking/wrinkling of fingers?

(c) What value of Anu is seen in the above cast?

Answer: (a) Fingers wrinkled because the cells of the skin lost some water.

(b) This happened because of the difference in the concentration of water in the skin cells and the swimming pool’s water.

(c) Anu showed the value of an aware citizen and a good learner who clarifies the doubts.

Question 3. Two sailors got marooned on the island, both of them were very thirsty and one of the sailors tried to drink sea water. The other sailor immediately stopped him from drinking the salty sea water and suggested he wait for some help, and stay calm and patient.

(a) What would happen if the sailor drinks salty water?

(b) What is osmosis?

(c) What value of sailors is reflected in the above act?

Answer: (a) On drinking sally water, exosmosis in the intestine will cause dehydration and vomiting.

(b) The movement of water molecules through a permeable membrane is called osmosis.

(c) Sailors showed the value of being patient, composed, empathy and determination.

Question 4. Sachin’s mother wanted to use some eggs for incubation. Sachin helped his mother in separating rotten and spoilt eggs from the good ones. He took a bucket of water to separate them.

(a) How can one separate the rotten eggs from the good ones using water?

(b) What is the shell of an egg made up of?

(c) What value of Sachin is seen in this act?

Answer: (a) We can separate the rotten eggs by dipping them in water. The eggs that will float in water are rotten eggs and the ones that sink are good one.

(b) Egg shells are made up of calcium carbonate.

(c) Sachin showed the value of being helpful, responsible behavior.

(a) What are lysosomes ? Why are they called “suicide bags of a cell” ?

(b) What happens to the dry raisins when we put them in plain water for some time ? State the reason for whatever is observed. What would happen if these raisins are now placed in concentrated salt solution ? (CCE 2010, 2011)

(a) Lysosomes. They are small, single membrane bound cell organelles which contain digestive enzymes for intracellular digestion and waste disposal.

Lysosomes contain digestive enzymes against all types of organic materials. If their covering membrane breaks as it happens during injury to the cell, the digestive enzymes will spill over the cell contents and digest the same. As lysosomes are organelles which on bursting can kill the cells possessing them, they are called suicide bags.

(b) Dry raisins placed in water swell up due to endosmosis or osmotic entry of water into them. The swollen raisins placed in concentrated salt solution will shrink in size and become wrinkled due to exosmosis or osmotic expulsion of water from them.

 

(a) Distinguish between chloroplast and leucoplast with respect to their pigments and function.

(b) How would

(i) a plant cell

(ii) an animal cell behaves when placed in a hypotonic solution of sodium chloride ? Explain giving reasons. (CCE 2010, 2011)

Answer:

(a)

(b) Cells placed in hypotonic solution swell up due to endosmosis or osmotic entry of water into them. Swelling is limited in plant cells as they have rigid cell walls. Due to absence of a cell wall, an animal cell will continue to swell up till it bursts.

 

(a) What is endoplasmic reticulum ?

(b) Describe its structure.

(c) Name two types of endoplasmic reticulum.

(d) What crucial role does it play in the liver cells of vertebrates ?

(e) What is membrane biosynthesis ?

(CCE 2010)

 

(a) Endoplasmic reticulum is a three dimensional interconnected network of membrane lined channels that run through the cytoplasm.

(b) Structure. Endoplasmic reticulum or ER has three components,

(i) Cisternae. They are interconnected flat sacs which run parallel to one another.

(ii) Tubules. They are tube-like extensions of cisternae.

(iii) Vesicles. They are oval or rounded sacs that are connected to cisternae and tubules. Membranes of endoplasmic reticulum are similar to plasma membranes but are thinner. The channels contain a fluid endoplasmic matrix.

(c) Types. There are two types of endoplasmic reticulum, smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). Rough endoplasmic reticulum bears ribosomes on its surface. The same is absent over SER.

(d) Detoxification. SER present in vertebrate liver detoxifies poisons and drugs.

(e) Membrane Biosynthesis. It is synthesis of cell membrane from its constituent proteins and lipids synthesized over endoplasmic reticulum and complexed by Golgi apparatus.

 

(a) Differentiate between

(i) The functions of RER and SER

(ii) Plasma membrane and cell wall.

(b) What is endocytosis ? (CCE 2010)

Answer:

(a) (i)

(ii) Differences between Plasma Membrane and Cell Wall.

(b) Endocytosis is the bulk transfer of materials from outside to inside of a cell with the help of special vesicles developed by plasma membranes. Organism (that feeds by endocytosis). Amoeba.

 

(a) Differentiate between

(i) Nucleus and nucleoid.

(ii) Plant cell and animal cell,

(b) What is osmosis ?   (CCE 2010)

Answer:

(a) (i) Differences between Nucleus and Nucleoid.

(ii) Plant Cell and Animal Cell.

(b) Osmosis: Diffusion of water through a semipermeable membrane from the region of its higher concentration (dilute solution) to the region of its lower concentration (concentrated solution) is known as osmosis.

 

(a) In the given diagram, identify the parts marked B and C.

(b) What are the substances that organelle A stores ?

(c) Mention one function of organelles B and C.

(d) What are cisterns ? (CCE 2010)

Answer:

(a) B —Golgi apparatus.

C — Chloroplast.

(b) A (Central Vacuole). It stores salts, sugar, amino acids, organic acids, some proteins and waste products. Recently lysosomal enzymes have also been detected in it.

(c) Function. :

(i) B — Secretion and excretion.

(ii) C — Photosynthesis.

(d) Cisterns. They are membrane bound curved flat stacks of Golgi bodies that bear tubules and vesicles on their periphery. Similar structures also occur in endoplasmic Ans. reticulum.

 

Observe the given figure and answer the questions.

(a) What has happened to cell A and B ? Explain.

(b) Identify the type of solution into which cells A and B are placed.

(c) Name and explain the process that has taken place in cells A and B. (CCE 2010)

Answer:

(a) Cell A has become turgid while cell B has become plasmolysed (flaccid).

(b) Cell A is placed in hypotonic solution while cell B is dipped in hypertonic solution.

(c) A—Endosmosis or osmotic entry of water has occurred. It is because cell sap has lower concentration of water while the outer solution has higher concentration of water.

Water moves from its higher concentration to lower concentration across a semipermeable membrane.

B —Exosmosis or osmotic expulsion of water has occurred. The cell sap has higher concentration of water than the external solution. Therefore, water passes from inside the cell to the outside.

 

(a) Draw a neat and labeled diagram of a prokaryotic cell.

(b) Why are organisms like bacteria called prokaryotes ?

(CCE 2010)

Answer:

(a)

(b) Bacteria are called prokaryotes because their genetic material is not organized into a nucleus. Instead it lies directly inside the cytoplasm as a nucleoid.

 

(a) Categorize plastids based on their color and function.

(b) Mention the strange similarity between plastids and mitochondria with reference to synthesis of their own materials. What do they synthesize ? (CCE 2010, 2012)

 

(a) Plastids are of three types on the basis of their color.

1. Colorless Plastids or Leucoplasts. Depending upon their storage product, they are of three types — amyloplasts (storage of starch), aleuroplasts (storage of proteins), and elaioplasts (storage of oil).

2. Brown-Red Plastids or Chromoplasts. They provide colouration to flowers and fruits for attracting pollinators and disseminators.

3. Green Plastids or Chloroplasts. They perform photosynthesis.

(b) Similarity Between Plastids and Mitochondria. They have their own DNA and ribosomes. Ribosomes are used to synthesize a part of proteins and enzymes required by the organelles. Rest of the materials are obtained from the cytoplasm of the cell. DNA and ribosomes make the two organelles semi-autonomous.

(a) What is lacking in a virus which makes it dependent on a living cell to multiply ?

(b) Expand RER and SER. Differentiate between their structure and function. (CCE 2010, 2011)

Answer:

(a) Virus does not have metabolic machinery as it lacks cytoplasm. Therefore, it is dependent upon the metabolic machinery of a living cell for multiplication.

(b) RER: Rough endoplasmic reticulum.

SER: Smooth endoplasmic reticulum.

 

Draw a labeled diagram of an animal cell and label the following organelles :

(a) The organelle that contains powerful digestive enzymes.

(b) The organelle that has its own DNA.

(c) The organelle that forms cytoplasmic framework

(d) The organelle that helps in expelling excess water in Amoeba. (CCE 2010)

Answer:

Labeling,

(a) Lysosome

(b) Mitochondrion

(c) Endoplasmic reticulum

(d) Vacuole (Contractile vacuole in Amoeba).

 

(a) Why do nuclear membranes have pores ?

(b) Why do chromosomes contain DNA in the nucleus ?

(c) Give two roles of the nucleus in the cell. (CCE 2010)

Answer:

(a) Pores in Nuclear Membrane. For allowing and controlling the exchange of materials between the nucleus and cytoplasm.

(b) Chromosomes Contain DNA in Nucleus, (i) In order to protect DNA from influence of cytoplasmic enzymes, (it) For separating transcription machinery from translation machinery.

(c)

1. Bodies of the living beings are made up of cells and their products.

2. Activities of an organism are the sum total of activities of its cells.

3. Cells develop from pre-existing cells.Viruses are an exception to cell theory.

 

(i) Draw a plant cell and label the parts which

(a) Is a dead layer and is permeable

(b) Is the kitchen of the cell

(c) Packages materials coming from endoplasmic reticulum

(d) Controls and regulates all the activities of the cell.

(ii) Identify the two structures which are present only in a typical plant cell. (CCE 2013)

 

(i)

(a) Cell wall

(b) Chloroplast

(c) Golgi apparatus

(d) Nucleus.

(ii) (a) Cell wall (b) Chloroplast/plastid.

 

(a) Draw a neat diagram of an animal cell and label the parts whose functions are as follows :

1. Helps in storage, modification and packaging of products in vesicles.

2. Helps in keeping the cell clean by digesting worn out cell organelles,

3. Helps in oxidation of glucose to produce energy in the form of ATP.

4. Allows the entry and exit of some materials into and out of cells.

(b) Define nuclei. (CCE 2014)

Answer:

(a)

1. Golgi apparatus

2. Lysosome

3. Mitochondrion

4. Plasma membrane.

(b) Nucleoid: Genetic material of prokaryotes which is devoid of a nuclear envelope and consists of a single compacted DNA molecule (equal to a single chromosome) is called nucleoid.

 

Do all cells of our body look alike in terms of shape, size and structure ? What similarities do they have ? (CCE 2015, 2016)

Illustrate by drawing diagrams of various cells present in the human body. (CCE 2015)

Answer:

No. Similarities,

1. Covering of plasma membrane.

2. Presence of centrally placed nucleus.

3. Cytoplasm and different cell organelles,

e.g., Golgi apparatus, lysosomes, mitochondria, ribosomes, endoplasmic reticulum. (iv) Metabolic pathways.

Cells become differentiated to perform different functions. They also come to have different shapes and sizes, e.g., nerve cell, bone cell, fat cell, ovum, sperm, blood cells, muscle fibers.

 

Draw and label a plant cell and write one main function of the following cell organelles :

(a) Chloroplast

(b) Plasma membrane

(c) Vacuole

(d) Lysosomes. (CCE 2015)

Answer:

(a) Chloroplast. Photosynthesis.

(b) Plasma membrane. Holding the cell contents and selective^^” permeability.

(c) Vacuole. Storage, dumping and development of osmotic concentration.

(d) Lysosome. Scavenging, intracellular digestion and defense.

 

Write differences between prokaryotic and eukaryotic cells.

Draw diagrams also. (CCE 2015)

Answer:

Diagrams :

 

 

(a) Why is the cell called a structural and functional unit of life ?

(b) Explain the concept of division of labor in multicellular organisms giving an example. (CCE 2015)

Answer:

(a) Structural Unit: A living organism is made up of one or more cells. Therefore, the cell is the structural unit of life. Functional Unit. All life functions of an organism reside in its cells. Cells may also become specialized to perform specific functions like contraction in muscle cells or impulse transmission in nerve cells. Therefore, cells are functional units of life.

(b) Division of labor is the taking up of different functions of the system/body by different specialized components in a coordinated fashion so that the whole is benefitted without any part put to overwork. It increases efficiency. In multicellular organisms like humans there are a number of organs, tissues and cells performing different functions, e.g. contraction and movement by muscle cells, transmission of impulses by nerve cells, transport of oxygen by RBCs, protection from germs by white blood corpuscles, gamete formation by germ cells, pumping of blood by heart, extraction of wastes by kidneys, etc.

Question 19.

On the basis of number of cells living organisms are classified as unicellular and multicellular,

(a) Name two unicellular organisms

(b) What is meant by division of labor in multicellular organisms,

(c) Name one prokaryotic and one eukaryotic unicellular organism ?

(d) Every multicellular organism has come from a single cell. Justify this statement.

(e) Write one common feature between in Amoeba and white

blood cells of humans. (CCE 2015)

Answer:

(а) Amoeba, Paramecium.

(b) Division of labor is the taking up of different functions of the system/body by different specialized components in a coordinated fashion so that the whole is benefitted without any part put to overwork. It increases efficiency. In multicellular organisms like humans there are a number of organs, tissues and cells performing different functions, e.g. contraction and movement by muscle cells, transmission of impulses by nerve cells, transport of oxygen by RBCs, protection from germs by white blood corpuscles, gamete formation by germ cells, pumping of blood by heart, extraction of wastes by kidneys, etc.

(c) Bacterium (prokaryotic, e.g., Escherichia coli), Chlamydemortas (eukaryotic).

(d) Every multicellular organism develops from a single cell called zygote, which is formed by fusion of two types of gametes.

(e) Both have irregular shape and perform endocytosis.

 

(a) Draw a neat diagram of a typical plant cell and label chloroplast and plasma membrane.

(b) State main function of

1. Mitochondria

2. Chloroplast.

(c) Write two differences between a plant cell and an animal cell. (CCE 2016)

Answer:

(a)

(b) Main Function,

1. Mitochondria: Aerobic respiration and energy release,

2. Chloroplast: Photosynthesis.

(c)

 

What is meant by osmosis ? State the following conditions :

(a) When the cell loses water and shrinks

(b) When there is no overall movement of water. How can the plant cell withstand very dilute external media without bursting?

(CCE 2016)

Answer:

Osmosis is diffusion of water from the region of its higher concentration (pure water or dilute solution) to the region of its lower concentration (strong solution) through a semipermeable membrane.

(a) Plasmolysis due to external solutions being hypertonic.

(b) External solution is isotonic.

A plant cell placed in a very dilute solution swells up, becomes turgid but further endosmosis stops due to a cell wall that begins to press the protoplasm inwardly.

(a) Differentiate between rough and smooth endoplasmic reticulum,

(b) How is endoplasmic reticulum important for membrane biosynthesis ? (CCE 2016)

Answer:

(a)

(b) Membrane Biosynthesis: It is synthesis of cell membrane from its constituent proteins and lipids synthesized over endoplasmic reticulum and complexed by Golgi apparatus.