Cells and Organisation Worksheet with Answers

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KS3 · Biology

K1 Cells and Organisation

AQA KS3 AQA KS3 Science Syllabus - Biology: Cells and Organisation · Calculator allowed · about 65 minutes

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

1

Which statement about cells is correct?

A) All living organisms are made of at least one cell.
B) All cells contain chloroplasts.
C) Cells can only be seen with the naked eye, without a microscope.
D) Animal cells have a rigid cell wall.

2

An animal cell contains several structures. For each description below, name the structure being described.

(a)Controls the substances entering and leaving the cell.(1)

(b)Contains the genetic material (DNA) and controls the cell's activities.(1)

(c)The jelly-like substance in which the cell's chemical reactions take place.(1)

(d)The structure where most respiration reactions happen, releasing energy for the cell.(1)

3

State two reasons why a living organism needs to produce new cells by cell division.

(2)

4

Plant cells contain some structures not found in animal cells.

(a)State the function of the cell wall.(1)

(b)State the function of the chloroplast.(1)

(c)State the function of the permanent vacuole.(1)

(d)State one reason why plant cells need a cell wall but animal cells do not.(1)

5

Cells, tissues, organs, organ systems and organisms show increasing levels of organisation.

(a)Put these in order of increasing size and complexity: organ, cell, tissue, organism, organ system.(2)

(b)Define the term "tissue".(1)

(c)Define the term "organ".(1)

(d)Name one organ system that contains the heart.(1)

6

The body has several organ systems.

(a)Name the organ system responsible for exchanging oxygen and carbon dioxide with the environment.(1)

(b)Name two organs found in this organ system.(2)

7

State three differences between a typical animal cell and a typical plant cell.

(3)

8

Cells can be specialised for a particular function.

(a)Sperm cells are specialised for reproduction. Describe two adaptations of a sperm cell that help it carry out its function.(2)

(b)Root hair cells are specialised for absorbing water and minerals. Describe how the structure of a root hair cell is adapted to its function.(2)

9

Diffusion is important in gas exchange.

(a)Define the term "diffusion".(2)

(b)Give a reason why oxygen moves from the air in the alveoli into the blood.(1)

10

Amoeba is an organism made of only one cell. Explain how a single cell is able to carry out all of the life processes needed for survival.

(3)

11

A student draws an onion cell as seen under a microscope. The actual width of the cell is 90 micrometres (0.09mm). The width of the student's drawing is 45mm. Calculate the magnification of the drawing. Use the equation: magnification = image size / actual size

(3)

12

A student is preparing a slide of onion cells to observe under a microscope. Below are five steps, labelled A to E, in the wrong order. Write down the letters in the correct order in which the student should carry out the steps.
A: Add a drop of iodine solution to stain the cells.
B: Peel a thin layer of epidermis (skin) from the inside of an onion.
C: Lower the coverslip onto the slide slowly using a mounted needle, avoiding air bubbles.
D: Place the piece of onion epidermis flat onto a microscope slide.
E: View the slide under the microscope, starting with the lowest-power objective lens.

(4)

13

A student's drawing of a cheek cell is 60mm wide. The drawing was magnified x1200. Calculate the actual width of the cell, giving your answer in micrometres.

(3)

14

Preparing and viewing a slide correctly requires good technique and safety awareness.

(a)Give one reason why a mounted needle, rather than fingers, is used to lower the coverslip onto the slide.(1)

(b)Give one safety precaution that should be followed when using iodine solution.(1)

(c)Explain why a student should start looking at a slide using the lowest-power objective lens before switching to a higher power.(2)

15

A student measured the diameter of five onion cells under a microscope. The results, in micrometres, were: 42, 39, 45, 41, 43. Calculate the mean diameter of the onion cells.

(3)

16

A pot plant is not watered for several days and its leaves become soft and droopy (it wilts). Explain, in terms of water movement, why the plant wilts.

(4)

17

A student counts the number of whole cells visible in the field of view at different magnifications.

Magnification	Number of whole cells visible
x100	20
x200	9
x400	2

(a)Describe the pattern shown by the data.(1)

(b)Suggest an explanation for this pattern.(2)

18

Stem cells are undifferentiated cells that can develop into different specialised cell types.

(a)State what is meant by a "stem cell".(1)

(b)Describe one way in which stem cells could be used to help treat a human disorder.(1)

(c)Give one ethical concern that some people have about using embryonic stem cells in medical research.(2)

19

Red blood cells, root hair cells and nerve cells are all cells that are specialised for their function. Explain how the structure of each of these three cell types is adapted to help it carry out its function.

(6)

20

A red blood cell has an actual diameter of 7 micrometres. A student wants to make a scale drawing of the cell magnified x1500. Calculate the diameter of the scale drawing, giving your answer in millimetres.

(4)

Mark scheme · K1 Cells and Organisation

Question 1

B1 A only, cao
Answer: A

Question 2

(a) B1 cell membrane, cao
(a) Answer: Cell membrane
(b) B1 nucleus, cao
(b) Answer: Nucleus
(c) B1 cytoplasm, cao
(c) Answer: Cytoplasm
(d) B1 mitochondria (accept mitochondrion), cao
(d) Answer: Mitochondria

Question 3

B1 growth (an increase in the number and/or size of cells as the organism gets bigger)
B1 repair (replacing cells that are damaged or worn out), oe
Answer: Growth and repair

Question 4

(a) B1 made of cellulose; supports/strengthens the cell and maintains its shape, oe
(a) Answer: Supports and strengthens the cell, keeping its shape.
(b) B1 absorbs light energy (contains chlorophyll) for photosynthesis, oe
(b) Answer: Absorbs light for photosynthesis.
(c) B1 contains cell sap; helps keep the cell rigid/turgid (support), oe
(c) Answer: Contains cell sap and keeps the cell turgid/rigid.
(d) B1 plants have no bony skeleton, so the cell wall gives structural support/strength (allows the plant to stand upright); OR the cell wall stops the cell bursting as water enters by osmosis, oe
(d) Answer: Plants have no skeleton, so the cell wall gives the plant support and stops cells bursting.

Question 5

(a) B2 all five in the correct order, cao: cell, tissue, organ, organ system, organism
(a) B1 if only one pair of adjacent items is transposed
(a) Answer: cell, tissue, organ, organ system, organism
(b) B1 a group of similar cells that work together to carry out a shared function, oe
(b) Answer: A group of similar cells working together to perform a shared function.
(c) B1 a structure made of two or more different tissues working together to perform a specific function, oe
(c) Answer: A structure made of different tissues working together for a specific function.
(d) B1 circulatory system (accept cardiovascular system), cao
(d) Answer: Circulatory system

Question 6

(a) B1 respiratory system, cao
(a) Answer: Respiratory system
(b) B1 any one of: lungs, trachea (windpipe), bronchi, bronchioles, diaphragm
(b) B1 any second, different organ from the same list
(b) Answer: Any two of: lungs, trachea, bronchi, bronchioles, diaphragm

Question 7

B1 a cell wall is present in plant cells and absent in animal cells
B1 chloroplasts are present in plant cells only (animal cells cannot photosynthesise)
B1 plant cells have one large, permanent vacuole; animal cells have small or no vacuoles, oe
Answer: Plant cells have a cell wall, chloroplasts and a large permanent vacuole; animal cells do not.

Question 8

(a) M1 has a long tail (flagellum) to swim towards the egg
(a) M1 contains many mitochondria to release energy (by respiration) for swimming
(a) Answer: A tail for swimming and many mitochondria for energy.
(b) M1 has a long, thin, hair-like extension, which increases the surface area of the cell
(b) M1 this allows more water and mineral ions to be absorbed (by diffusion/osmosis), ft from first point
(b) Answer: A long hair-like extension increases surface area for water and mineral absorption.

Question 9

(a) M1 the (net) movement of particles from an area of higher concentration to an area of lower concentration
(a) A1 down a concentration gradient (until particles are evenly spread), oe
(a) Answer: Net movement of particles from high to low concentration, down a concentration gradient.
(b) B1 the concentration of oxygen is higher in the alveolar air than in the blood, so oxygen diffuses down its concentration gradient into the blood, oe
(b) Answer: Oxygen concentration is higher in the alveoli than in the blood, so it diffuses in.

Question 10

B1 any one of: the cell membrane controls substances entering/leaving the cell (e.g. taking in food/oxygen, removing waste)
B1 any second, different point, e.g. the cytoplasm is where chemical/metabolic reactions such as respiration take place; the cell can change shape/move using pseudopodia to find and engulf food; a contractile vacuole removes excess water; the nucleus controls all of the cell's activities as there are no other cells to share the work
B1 any third, different valid point from the list above, oe
Answer: The single cell's membrane, cytoplasm, nucleus and other structures each take on all of the roles that would otherwise be shared between many specialised cells.

Question 11

M1 converts units so both sizes are in the same unit: 90 micrometres = 0.09mm
M1 substitutes into the equation: magnification = 45 / 0.09
A1 500 (accept x500 or "500 times"), cao
Answer: x500

Question 12

B4 correct order B, D, A, C, E, cao
B2 if only one pair of adjacent steps is transposed, oe
Answer: B, D, A, C, E

Question 13

M1 rearranges the equation: actual size = image size / magnification
M1 substitutes values: 60 / 1200 = 0.05 (mm)
A1 converts to micrometres: 50 micrometres, cao
Answer: 50 micrometres

Question 14

(a) B1 to avoid trapping air bubbles under the coverslip (which would block the view of the cells); OR to avoid pushing too hard and cracking the slide/coverslip, oe
(a) Answer: To avoid trapping air bubbles under the coverslip.
(b) B1 iodine is an irritant/stains skin, so avoid contact with skin and eyes; OR wear eye protection; OR wash hands after use, oe
(b) Answer: Avoid contact with skin and eyes (wear eye protection).
(c) M1 the lowest power gives the widest field of view, making it easier to locate the specimen/cells
(c) M1 once located, the student can switch to a higher power for a more detailed/magnified view of a smaller area, ft
(c) Answer: Low power gives a wide field of view to find the specimen, then higher power gives more detail.

Question 15

M1 sums the five values: 42 + 39 + 45 + 41 + 43 = 210
M1 divides the total by 5
A1 42 micrometres, cao
Answer: 42 micrometres

Question 16

B1 the concentration of water is lower in the soil than inside the plant's root cells
B1 water moves out of the plant's cells (and roots) into the drier soil, ft
B1 this happens by osmosis, through the partially permeable cell membrane
B1 as cells lose water they become flaccid and lose turgor pressure, so the plant loses its rigidity/support and wilts, ft
Answer: Water moves out of plant cells by osmosis into drier surroundings; cells lose turgor pressure and the plant wilts.

Question 17

(a) B1 as magnification increases, the number of (whole) cells visible in the field of view decreases, oe
(a) Answer: As magnification increases, fewer whole cells are visible.
(b) M1 increasing the magnification reduces the area of the specimen shown (the field of view becomes smaller)
(b) M1 so fewer whole cells fit into/are visible within the smaller area seen, ft
(b) Answer: Higher magnification shows a smaller field of view, so fewer whole cells fit within it.

Question 18

(a) B1 an undifferentiated (unspecialised) cell that can divide to produce more cells and can become different types of specialised cell, oe
(a) Answer: An unspecialised cell that can divide and become different specialised cell types.
(b) B1 e.g. bone marrow stem cells can be used to produce new blood cells for a patient with a blood disorder such as leukaemia; OR stem cells could be grown into replacement cells/tissues for a damaged organ, oe
(b) Answer: Bone marrow stem cells can produce new blood cells for patients with blood disorders.
(c) M1 obtaining embryonic stem cells usually destroys the embryo
(c) M1 some people believe the embryo is/could become a human life, so consider this morally wrong, ft; (accept alternative developed points about consent or when life begins)
(c) Answer: Taking embryonic stem cells destroys the embryo, which some consider a potential human life.

Question 19

Level 1 (1-2): Basic, isolated statements about one or two of the cell types, with little or no link made between structure and function. Answers may simply name a cell or a structure without explanation.
Level 2 (3-4): Some clear links made between structure and function for at least two of the three cell types, using mostly appropriate scientific terms.
Level 3 (5-6): Clear, detailed and logically linked explanations of how structure relates to function for all three cell types, using accurate scientific terminology throughout.
Indicative content:
- Red blood cells have no nucleus, which leaves more space to carry oxygen.
- Red blood cells contain haemoglobin, which binds to/carries oxygen.
- Red blood cells have a biconcave disc shape, which increases their surface area for gas exchange/oxygen uptake.
- Root hair cells have a long, thin, hair-like extension, which increases the surface area for absorbing water and mineral ions.
- Root hair cells may contain more mitochondria to provide energy for the active transport of mineral ions.
- Nerve cells have a long axon, which allows electrical impulses to travel quickly over long distances in the body.
- Nerve cells have branched dendrites, which allow them to connect with and receive impulses from many other neurones.
- Nerve cells may be covered in a myelin sheath, which insulates the axon and speeds up the transmission of impulses.

Question 20

M1 rearranges the equation: image size = actual size x magnification
M1 substitutes values: 7 x 1500 = 10500
M1 converts micrometres to millimetres (divides by 1000)
A1 10.5mm, cao
Answer: 10.5mm

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