B1 - 1 Key concepts in Biology - Questions Q1. Figure 1 is an electron micrograph showing a cross section through a neurone. Figure 1 The myelin sheath of this neurone is 250 nm in thickness. Calculate the magnification of this electron micrograph. (3) magnification ........................................................... Q2. Figure 6 shows a photomicrograph of onion cells. Figure 2 (i) The width of the labelled cell in Figure 6 is 6 mm. The cell has been magnified 750 times. Calculate the actual width of this cell in mm. Give your answer in standard form. (3) (ii) The most appropriate unit of measurement to record the length of a cell under a light microscope is a (1) A centimetre B micrometre C nanometre D picometre Q3. Yeasts are microorganisms that are used in the brewing and baking industries.
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B1 - 1 Key concepts in Biology - Questions Q1. Figure 1 is an electron micrograph showing a cross section through a neurone.
Figure 1
The myelin sheath of this neurone is 250 nm in thickness.
Calculate the magnification of this electron micrograph. (3)
magnification ........................................................... Q2. Figure 6 shows a photomicrograph of onion cells.
Figure 2
(i) The width of the labelled cell in Figure 6 is 6 mm. The cell has been magnified 750 times. Calculate the actual width of this cell in mm. Give your answer in standard form. (3)
(ii) The most appropriate unit of measurement to record the length of a cell under a light microscope is a (1)
A centimetre
B micrometre
C nanometre
D picometre
Q3. Yeasts are microorganisms that are used in the brewing and baking industries.
The diagram shows a yeast cell.
(a) (i) State two ways in which the structure of this yeast cell differs from the structure of a bacterial cell. 2)
(ii) Describe the functions of white blood cells. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. (iii) Person B has a low number of red blood cells compared to the healthy person.
Suggest an effect this may have on person B. (1) .............................................................................................................................................. ..............................................................................................................................................
Q4. The diagram shows a human sperm cell.
(a) (i) Structure X on the diagram contains DNA. Name structure X. (1)
............................................................................................................................................. (ii) Which statement is true for DNA?
Place a cross ( ) in the box next to your answer. (1) A DNA is made up of amino acids and bases.
B DNA is made up of amino acids which give instructions to make proteins.
C In DNA, the bases A and T are complementary.
D Every gene in a DNA molecule contains only three bases.
(b) Sperm cells are involved in fertilisation. Define fertilisation. (2)
............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) (i) Describe the function of mitochondria. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Gene mutations in DNA can produce abnormal mitochondria.
Explain how a gene mutation can produce a different protein. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
Q5. State why egg cells have a large amount of cytoplasm. (1) .............................................................................................................................................. .............................................................................................................................................. Q6. The diagram shows a sperm cell.
Complete the sentence by putting a cross ( ) in the box next to your answer. The acrosome contains (1)
A enzymes to help get through the membrane of the egg cell
B mitochondria to supply energy to swim
C muscle fibres to swim
D 23 chromosomes
Q7. DNA can code for the amino acids in the active site of an enzyme. Explain the role of the active site of an enzyme. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. Q8. The diagram shows how the human insulin gene can be used to genetically modify bacteria.
(a) (i) Name the enzyme used to join the insulin gene to the plasmid. (1)
............................................................................................................................................. (ii) Suggest why the same restriction enzyme was used to cut the human chromosome and the plasmid. (2)
*(b) Enzyme technology can be used in the production of foods including sweets, vegetarian cheese and lactose-free milk.
Describe how enzyme technology can be used to produce these food products. (6) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) Washing powders can be biological or non-biological.
Describe how biological washing powders can make clothes cleaner than nonbiological washing powders.
Q9. DNA and RNA are involved in the synthesis of proteins such as enzymes. (a) Protein synthesis involves transcription and translation.
Which row shows the molecules involved in both transcription and translation? Place a cross ( ) in the box next to your answer. (1)
(b) Describe what happens to the molecule produced by transcription before it is translated. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(c) Explain how the lock and key hypothesis models how enzymes work.
You may use labelled diagrams in your answer. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. *(d) Describe how named factors affect the rate of enzyme-catalysed reactions. (6) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Q10. Figure 3 shows how a student set up equipment to investigate the effect of pH on the action of the enzyme pepsin on boiled egg white.
Figure 3
The length of egg white in each of the tubes was measured after 24 hours.
The results are shown in Figure 4.
Figure 4
The student extended his experiment by replacing the boiled egg white with fat.
Explain why there was no change in the length of the fat in the tube at any of the different pH solutions containing pepsin. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Q11. Yogurt can be produced by adding a starter culture of microorganisms to milk.
The starter culture was added to milk kept at 20°C. The pH was recorded over 10 hours. This was repeated with milk kept at 40°C and 60°C. The graph shows the results.
Using the information in the graph, explain how temperature affects the fermentation process during yogurt production. (6) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Q12. Figure 3 shows how a student set up equipment to investigate the effect of pH on the action of the enzyme pepsin on boiled egg white.
Figure 3
The length of egg white in each of the tubes was measured after 24 hours.
The results are shown in Figure 4.
Figure 4
(i) State the pH at which pepsin was most effective. (1)
(ii) State how the pH of a solution can be measured. (1) ............................................................................................................................................. ............................................................................................................................................. (iii) The student noticed that the boiled egg white in some of the tubes also became thinner.
Describe how the method could be improved to obtain a more accurate measure of how much boiled egg white was digested by the pepsin.
(2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Q13. Catalase is an enzyme.
Catalase breaks down hydrogen peroxide into oxygen and water.
(a) The effect of pH on the activity of catalase was investigated. The volume of oxygen produced in one minute at each pH was recorded.
The results can be seen in Figure 11.
Figure 11 (i) Describe the effect of pH on the activity of catalase. (2)
(ii) Explain why the volume of oxygen produced changes above pH 7. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(iii) The investigation was improved. State two variables that should be controlled in the improved method. (2)
1 .......................................................................................................................................... 2 .......................................................................................................................................... (b) The results for the improved method are shown in Figure 12.
Figure 12
(i) Calculate the most appropriate mean volume of oxygen produced at pH 7. (2)
........................................................... cm3 (ii) Describe how the method could be developed to find the optimum pH for catalase activity.
* Describe the roles of the enzymes involved in digestion. (6)
.............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. Q15. Some students investigated the effect of sucrose concentration on the change in mass of beetroot chips. A beetroot chip was weighed, immersed in water for 30 minutes and then reweighed. This was repeated using five more beetroot chips and five different concentrations of sucrose solution. The results are shown in Figure 8.
Figure 8
(i) Calculate the percentage change in mass for chip 5. Give your answer to an appropriate number of decimal places.
(ii) Explain the difference in the changes in mass of chip 5 and chip 2. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
Q16. Factors affecting the rate of diffusion can be investigated using agar cubes.
The agar cubes contain an indicator called phenolphthalein.
Phenolphthalein is colourless, but turns pink in the presence of an alkali, such as sodium hydroxide solution.
Cubes of agar, with sides 3 cm, 2 cm and 1 cm, are placed into sodium hydroxide solution for 10 minutes.
The cubes are then cut in half to see how far the sodium hydroxide solution has diffused into them.
Figure 5 shows the results.
Figure 5
(i) Calculate the surface area to volume ratio for the cube with side 3 cm. (1)
(ii) Calculate the rate of diffusion for the 10 minutes of the investigation. (1)
........................................................... cm per min
(iii) Describe the effect of the size of the cube on the rate of diffusion. (1) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(iv) Explain why the sodium hydroxide diffuses into the cube. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Q17. Some students investigated the effect of sucrose concentration on the change in mass of beetroot chips.
A beetroot chip was weighed, immersed in water for 30 minutes and then reweighed. This was repeated using five more beetroot chips and five different concentrations of sucrose solution. The results are shown in Figure 8.
Figure 8
* A student set up an experiment to investigate osmosis as shown in Figure 9.
The student used visking tubing which is a partially permeable membrane.
The student put 25 cm3 of 20% sucrose solution into visking tube 1 and 25 cm3 of distilled water into visking tube 2.
Both tubes were placed in a 5% sucrose solution and left for 1 hour.
Figure 9
Explain how and why tube 1 and tube 2 would look different after one hour. (6) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
Q18. Answer the question with a cross in the box you think is correct . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
(i) Which of the following describes osmosis? (1)
A does not use energy to move water into cells
B does not use energy to move glucose into cells
C uses energy to move water into cells
D uses energy to move glucose into cells
(ii) Animal cells will swell and burst when placed in a hypotonic solution.
Explain what happens to plant cells when they are placed in a hypotonic solution. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Q19. Visking tubing is made of a plastic material through which small molecules can pass.
The diagram shows how the equipment for an investigation using visking tubing was set up.
In this investigation, the concentration of glucose in the distilled water was measured at the start and then every five minutes. The results are shown in the table.
(i) Describe the results of this investigation. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. (ii) Explain the results of this investigation (3) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. *(iii) The diagram shows how visking tubing can be used to model the small intestine.
This model does not fully represent the structure and functions of the small intestine. Evaluate the strengths and weaknesses of this model. (6)
.............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. Q20. Some students investigated water movement in plant cells. They measured the mass of five pieces of potato.
Each piece of potato was put into a different concentration of salt solution.
After one hour the pieces of potato were dried and the mass of each was recorded.
The results are shown in the table.
(a) (i) Calculate the percentage change in the mass of the potato in the 20% salt solution. (2)
........................................................... % (ii) Suggest why calculating a percentage change is more useful than calculating the change in mass in this investigation. (1)
Describe the division of a cell by mitosis. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. *(c) Explain how active transport and diffusion provide a plant with named substances it needs for growth. (6)
Q21. Visking tubing is made of a plastic material through which small molecules can pass. The diagram shows how the equipment for an investigation using visking tubing was set up.
(a) In this investigation, the concentration of glucose in the distilled water was measured at the start and then every five minutes.
The results are shown in the table.
(i) Describe the results of this investigation. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
(ii) Explain the results of this investigation (3) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
*(iii) The diagram shows how visking tubing can be used to model the small intestine. This model does not fully represent the structure and functions of the small intestine. Evaluate the strengths and weaknesses of this model. (6)
(b) Complete the sentence by putting a cross ( ) in the box next to your answer. The function of the gall bladder is to (1)
A make bile
B make lipase
C store bile
D store lipase Q22. (a) Complete the sentence by putting a cross ( ) in the box next to your answer.
Food is moved through the digestive system by (1) A diffusion B digestion C peristalsis D active transport
(b) State two roles of bile in digestion. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
*(c) Describe the roles of the enzymes involved in digestion. (6) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
(d) Explain how the structure of the villi allows efficient absorption in the small intestine. (3) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. Q23. Complete the sentence by putting a cross ( ) in the box next to your answer.
Food is moved through the digestive system by (1)
A diffusion
B digestion
C peristalsis
D active transport
Q24. Complete the sentence by putting a cross ( ) in the box next to your answer. The function of the gall bladder is to (1)
A make bile
B make lipase
C store bile
D store lipase
Q25. Name the product formed when the protein in boiled egg white is broken down. (1) .............................................................................................................................................
Q26. Proteins are made up of amino acids. (a) The table shows the DNA bases that code for some of the amino acids found in proteins.
Part of the DNA coding for a protein is:
(i) State the order of amino acids coded for by this sequence of DNA. (1) ..............................................................................................................................................
(ii) These amino acids will be joined together during protein synthesis. During which stage of protein synthesis will this take place? (1) ..............................................................................................................................................
(iii) Complete the sentence by putting a cross ( ) in the box next to your answer. Amino acids are joined together (1)
A at the membrane B in the mitochondria C in the nucleus D at the ribosome
(b) DNA can code for the amino acids in the active site of an enzyme. Explain the role of the active site of an enzyme. (2) .............................................................................................................................................. ..............................................................................................................................................
(c) Mutations can occur in DNA. Describe what effect a mutation could have on the action of an enzyme. (3) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
Q27. State two roles of bile in digestion. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. Q28. Figure 7 shows the steps involved in making a slide to observe mitosis in plant tissue.
Figure 7
Answer the question with a cross in the box you think is correct . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
(i) To observe mitosis, the plant tissue should be removed from the(1)
A middle of the root
B centre of the stem
C middle of the leaf cell
D tip of the root
(ii) State why the stain is added to the plant tissue in step 3. (1)
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