You Cells COPYRIGHT · (a) A cell is the basic unit of life for all the living organisms. (b) (i) A unicellular organism is made up of one cell only. A multicellular organism is made

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Cells 1. Which of the locations in the cell can the genetic materials be found? A. Cytoplasm B. Nucleus C. Vacuole D. Chloroplast 2. The diagram shows a typical plant cell. Which of the structures are not found in a typical animal cell? A. U and V B. X and Y C. U and X D. Y and U

3. The diagrams show a typical plant cell and a typical root hair cell. Which of the cell organelles is not found in a root hair cell? A. Vacuole B. Cellulose wall C. Nucleus D. Chloroplast 4. At which location in a cell that chemical reactions are most likely to take place? A. Cytoplasm B. Nucleus C. Vacuole D. Cell membrane 5. Which of the following correctly describes the function of vacuole? A. It stores the genetic materials of an organism. B. It captures sunlight so that plant cells can synthesise food. C. It allows most of the chemical reactions to take place in the cell. D. It stores food in the cell. 6. What is the benefit of having a labour of division in a multicellular living organism? A. It reduces the energy requirement in a multicellular living organism. B. It enables efficient functioning of the processes in a multicellular living organism. C. It reduces the waste products produced in a multicellular living organism. D. It enables the multicellular living organism to defend the bacteria better. 7. Which of the following descriptions is correct about tissues? A. They are a group of cells performing similar functions. B. They are a group of organs performing similar functions. C. They are a group of systems performing similar functions. D. They are a group of organisms performing similar functions

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8. Which of the following cell organelles provides regular shape for a cell as one of its functions? A. Cell membrane B. Cellular cell wall C. Cytoplasm D. Vacuole 9. The diagram below shows an unknown cell and a plant cell

How is the unknown cell similar to the plant cell? A. Both contain one big vacuole. B. Both have chloroplast. C. Both have cell wall. D. Both have hairy structures around the cells. 10. Which of the following characteristics is not found in a typical human cheek cell? A. It contains nucleus. B. It contains cell membrane. C. It contains many small vacuoles. D. It has biconcave shape. 11. Which of the following is not found in a typical animal cell? A. Cell membrane B. Nucleus C. Vacuole D. Cell wall 12. Which of the following statements is correct about cells in living organisms? A. They are the basic unit of life for animals only. B. Plant cells and animal cells differ in terms of shape only. C. A multicellular organism has only one cell in its body. D. A unicellular organism needs a nucleus to survive longer. 13. Which of the following is the function of cell walls? A. Control the movement of substances across the cell B. Maintain the shape of a cell C. Allow chemical reaction to take place D. Provide energy for cell survival 16. Which of the following forms an organ? A. A group of tissues B. A group of systems C. A group of organs D. A group of cells 17. What is the name of the system that consists of stomach and the small intestine? A. The reproductive system B. The circulatory system

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C. The digestive system D. The nervous system Question 14 and 15 refers to the diagram below.

A. P B. Q C. R D. S

14. Which of the structures controls the movement of substances across the cell? (A) 15. Which of the structures is absent in the red blood cell which causes it to have short life span? (B) 18. Which of the following cells are found in plants? I. Phloem tissue II. Muscular tissue III. Root hair cells A. I, II B. I, III C. II, III D. I, II, III 19. Which of the following is not a multicellular organism? A. Lion B. Ant C. Earthworm D. Amoeba 20. Which of the following organs are parts of the nervous system? A. The heart and the blood vessels B. Sperm duct and penis C. Trachea and bronchi D. Brain and spinal cord

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Short answer questions 1.(a) Define a cell. (b) What is the difference between a unicellular organism and a multicellular organism? Give one example for each organism in (b)(i). (a) A cell is the basic unit of life for all the living organisms.

(b) (i) A unicellular organism is made up of one cell only.

A multicellular organism is made up of many cells.

(ii) Unicellular organism: Amoeba

Multicellular organism: Human

Extra info for unicellular

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2. The diagram on the right shows a typical plant cell. (a) Label the parts P, Q. (b) State two functions of R. (c) Why is S important to the survival of a cell? (a) (i) P: Chloroplast

(ii) Q: Vacuole

(b) R provides support to the cell. It also maintains the shape of the cell.

(c) It is a place that allows most of the essential chemical reactions to take place.

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3. The diagrams show a typical plant cell and a root hair cell. (a) State the structures which are similar in both cells. (b) A root hair cell is a modification from the typical plant cell. State two modifications shown in the diagram. (c) How does the structure X enable the root hair cell to function efficiently?

(a) Both have cellular cell wall, thin cytoplasm, nucleus and a big vacuole.

(b) No chloroplast; Elongated cell structure

(c) It increases the surface area for water and mineral salts to enter, so the

uptake of water and mineral salts is faster.

Extra info for root hair

A plant’s root system anchors it in the soil, absorbs and transports minerals and

water, and stores food. Near the root tips, a vast number of tiny tubular

projections called root hairs enormously increase the root surface area for

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absorption of water and minerals. As shown on the far right of the figure, each

root hair is an extension of an epidermal cell (a cell in the outer layer of the root).

It is difficult to move an established plant without injuring it because

transplantation often damages the plant’s delicate root hairs.

In actively growing plants, new roots grow into different patches of soil. The

roots are not “exploring” the soil; their growth is simply greater in areas where

the water and nutrient concentrations best match the requirements of the

particular plant. Certain specializations of roots help plants take up water and

minerals. Mycorrhizae and root hairs absorb water and ions from the soil, and

bacteria in root nodules absorb nitrogen from the air.

Root Hairs : As a plant adds primary growth, its root sys-tem may develop

billions of tiny root hairs (Figure 26.4A). Collectively, these thin extensions of

root epidermal cells enormously increase the surface area available for

absorbing water and nutrients. Root hairs are fragile structures no more than a

few millimeters long. They do not develop into new roots, and last only a few

days.

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4. (a) List the labour of division in a living organism. (b) Explain the importance of the labour of division in a living organism. (c) The following shows a unicellular organism known as amoeba. Explain why there is no need for an amoeba to have the labour of division. (a) Cells Tissues Organs Organ systems Organism

(b) Division of labour enables cells to develop special features to carry out their

functions effectively and efficiently so that an organism can survive better.

(c) An unicellular organism is in contact with the surroundings directly. It

obtains nutrients and removes waste products between the cell and the

surroundings.

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5. The following diagrams show a few types of cell in our bodies

(a) Explain how these cells are different from a typical animal cell. (b) How do the modifications in the red blood cells enable them to carry out their functions more effectively? Give two modifications. (c) Name the systems in our bodies which contain (i) Red blood cell (ii) Muscle cell (iii) Nerve cell (a) They have special features to perform their functions.

(b) By having no nucleus, it can contain more haemoglobins.

By having biconcave shape, it can squeeze through narrow blood capillaries with ease.

(c) (i) Red blood cell: Circulatory system

(ii) Muscle cell: Muscular system

(iii) Nerve cell: Nervous system

Extra info for red blood cell.

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Red blood cells, shown in Figure 46-11, transport oxygen to cells in all parts of the

body. Red blood cells are formed in the red marrow of bones. Immature red blood cells

synthesize large amounts of an iron-containing protein called hemoglobin.

Haemoglobin is the molecule that actually transports oxygen and, to a lesser degree,

carbon dioxide. During the formation of a red blood cell, its cell nucleus and organelles

disintegrate. The mature red blood cell is little more than a membrane containing

haemoglobin. Because red blood cells lack nuclei, they cannot divide and they have a

limited survival period, usually 120 to 130 days. Of the more than 30 trillion red blood

cells circulating throughout the body at one time, 2 million disintegrate every second.

To replace them, new ones form at the same rate in the red marrow of bones. Some

parts of the disintegrated red blood cells are recycled. For example, the iron portion of

the hemoglobin molecule is carried in the blood to the marrow, where it is reused in

new red blood cells.

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6. (a) Explain why heart is considered as an organ. (b) The heart is part of a system in our bodies. Name the system. (c) Why is it important to have different systems in multicellular organisms? (a) It is made up of different tissues performing similar tasks.

(b) Circulatory system

(c) So that it ensures the smooth and efficient functioning in multicellular organisms

7. Study the cell as shown. (a) How is this cell similar to an animal cell? List one similarity. (b) How is this cell similar to a plant cell? List two similarities. (c) The cell may not live for a few months. Explain. (d) Will the cell be able to make food on its own? Explain. (a) It does not have cell wall.

(b) It contains chloroplast. It has one big vacuole.

(c) It does not have nucleus.

(d) Yes. Chloroplast have chlorophyll that are able to capture sunlight for

photosynthesis.

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8.(a) The diagram below shows the outline of a root hair cell. Complete, and label, the diagram by adding the following cell organelles:

Cell membrane Vacuole Cell wall Cytoplasm Nucleus (b) Explain why the root hair cell is a specialised cell. (c) How does a root hair cell increase its function efficiency? (d) Give another specialised cell which can be found in a plant. (a)

(b) It does not have chloroplast. It has the elongated structure.

(c) By having the elongated structure, it increases the surface area for water and

mineral salts absorption.

(d) Xylem or phloem

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9. The photomicrograph below shows onion epidermal cells. (a) Which organelle normally present in plant cells is absent in the onion epidermal cells? (b) Label the nucleus, cell membrane and cell wall in the above photomicrograph. (c) It is often difficult to identify organelles of a cell when viewed under the microscope. Suggest one way to overcome this. (a) Chloroplast

(b)

(c) Conduct staining, using iodine for example.

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10. The figure below shows a cell from an organism. (a)(i) In which type of living organism are cells similar to cell X normally found? (ii) State two reasons for your choice of the living organism in (a)(i). (b)(i) Name the part labelled Y. (ii) Name an organelle found in Y that is not shown in the diagram. (iii) State the function of the named organelle in living organisms. (c)(i) State the function of cell X. (ii) Explain how cell X is adapted for its function stated in (c)(i). (iii) What is 'division of labour'? Explain how division of labour occurs in cell X. (a) (i) Plants

(ii) Cell X has a cell wall and large central vacuole like plant cells.

(b) (i) Cytoplasm

(ii) Mitochondrion

(iii) To produce energy

(c) (i) To absorb water and mineral salts

(ii) Long and narrow, increases surface area to volume ratio for absorption of water

and mineral salts. (Better answer)

[Whenever something is long and many, the purpose is to increase surface area to

volume ratio so that some physical processes can take place efficiently]

(iii) The work needed to be done in the functioning of the cells is carried out by different

organelles. The nucleus controls genetic information, the cell wall maintains the shape

of the cell, the vacuole stores water and dissolved materials, and the cell membrane

encloses and protects the contents of the cell.

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11. Fig. 9.5 shows the structures underside of a leaf. Cell A and cell B are collectively known as the epidermal tissue. They help to reduce water loss from the plant. Guard cells allow exchange of gases to take place between the leaf and the atmosphere through their opening pores. (a) Explain why cell A and cell B are classified as a tissue. (b) How does structure 1 play an important role in the structure of a leaf cell? (c) Structure 2 provides food to the cell. Describe briefly how this structure supply the food to the cells. (d) Explain why a leaf is an organ to a plant. (a) They are a group of similar cells performing a specific function.

(b) It provides support and maintains the shape of the cell.

(c) It contains chlorophyll which can convert carbon dioxide and water into glucose in

the presence of sunlight.

(d) It is made up of a group of tissues such as epidermal tissue and guard cells which

work together to carry out functions efficiently for time survival of time plant.

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12. Fig. 9.6 shows the structure of a typical plant cell.

When structure X is absent, only substance B can be found in the cytoplasm. When structure Y is absent, both substances A and B can be found in the cytoplasm (a)(i) Which structure, X or Y. is a partially permeable membrane? (ii) Explain your answer clearly. (b)(i) Name the structure Z. (ii) State two important functions of this structure. (a)(i) Y

(ii) It only allows substance B to enter the cell but not substance A.

Therefore, it controls the movement of substance entering the cell.

(b)(i) Nucleus

(ii) It controls all the activities taking place in the cell. COPYRIGHT

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It is responsible for cell reproduction.

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13. Division of labour is normally observed in multicellular organisms such as humans. Fig. 9.4 shows a structure found in humans.

(a)(i) What is division of labour? (ii) Explain why division of labour is important for multicellular organism. (b)(i) How is stomach classified in division of lab our in humans? (ii) Explain your answer from the evidence shown in the diagram. (c) State one difference between red blood cells and the other tissues shown in the diagram. (a)(i) It is a process whereby each type of cell is specialised to carry out a specific task.

(ii) It ensures that each cell can have a smooth amid efficient function so that the

multicellular organism can function efficiently as a whole.

(b)(i) organ

(ii) It shows that stomach is made up of a group of different tissues that work together

to do a specific task in humans.

(c) They do not contain nucleus.

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14. Fig 9.1 shows the structure of typical human cheek cells seen through a microscope.

(a)(i) Name part 1 shown in the diagram. [1 m] (ii) Explain why part 1 is Important to safeguard the survival of the cheek cells. [1 m] (b) Why do the human cheek cells contain numerous cell structures 2? (c) There are some thread—like structures found in each human cell in structure 3. (i) Name the substance that is used to make these structures [1 m] (ii) What is the important role played by these thread-like structures? [1 m] (a) (i) Cell membrane

(ii) It controls the movements of substances in and out of the cells so that only useful

substances can enter the cells and waste substances can leave the cells.

(b) They store water and other important nutrients for the human cheek cells to survive.

(c) (i) They are made of deoxyribonucleic acid (DNA).

(ii) They contain hereditary materials which pass down from one generation to the next.

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Extra Practice

1. (a) Give four differences between a plant cell and an animal cell.

(b) In animals and plants, cells are usually specialised. Give one example each in

animals and plants and explain the importance of specialisation.

2. Fig. 9.2 shows the structure of a typical plant cell.

(a)(i) Name the cell structure P. [1 m]

(ii) State the main function of this structure. [1 m]

(b)(i) Name the cell organelle Q.

(ii) Hence, explain why the survival of animals depends on this plant in an ecosystem.

[2 m]

(c) Explain why part R plays an important role n the respiration of this cell. [1 m]

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3, Fig. 9.3 shows the structure of a cell.

(a)(i) What type of cell: animal or plant, is shown in this diagram? [1 m]

(ii) Give two reasons for your answer. [2 m]

(b)(i) Name the structure P [1 m]

(ii) Explain why structure P does not carry out all the activities in the cell. [1 m]

(iii) How can the cell have all the activities required for its survival? [1 m]

(c) Complete the table below to name and state the function of the following structures.

[4 m]

Structure Name Function

Q

R

4. (a) What is the labour of division?

(b) Using the respiratory system and the circulatory system as the examples, explain

briefly how the labour of division works in a multicellular organism.

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