1. Compare aerobic and anaerobic respiration
Compare aerobic and anaerobic respiration. Your answer should refer to the use of oxygen, the products and the amount of energy released. [4]
Describe three situations in living organisms in which anaerobic respiration takes place [3]
The diagram shows some structures in a yeast cell.
Explain how the properties of these structures help the yeast cell to respire using aerobic and anaerobic respiration. [6]
Write down the names of the structures A and B. A:
B: [1]
Write a balanced symbol equation for aerobic respiration [2]

2. A scientist analysed a sample of DNA from a muscle cell.
A gene mutation takes place and inserts a base in-between 2 of the original bases in the DNA strand. The diagram shows a section of one of the 2 strands of DNA. A geneticist predicts that the mutated gene is likely to affect the type of protein produced. Explain why this is likely to be true. [3]
A scientist analysed a sample of DNA from a muscle cell.
It is found that 21% of the bases are A. Calculate the % of bases that are G.
[1]
Use your knowledge of the genetic code to explain where and how proteins are coded for and made. [6]
Genes are part of a strand of DNA.
How do different genes make different proteins. [3]
Complete the sentences.
Genetic code is found in the cell _________
Proteins are formed in the cell___________
The genetic code is found on DNA.
The number of strands in a DNA molecule is _____
The number of different bases in DNA is ____ [2]

3. Compare the processes of osmosis, diffusion and active transport. [4]
The diagram shows a root hair cell.
What is the name of the process by which soil water moves into the root hair cell? [1]
In an experiment, Adam cut and weighed 2 potato chips. He placed one in distilled water and the other in a concentrated sucrose solution. After 30 minutes he weighed them again. How did the mass of the chips change? Explain your answer. [6]
Write down three situations in living organisms in which anaerobic respiration takes place. [3]
Plants also need a source of nitrogen to grow.
Some plants grow poorly in waterlogged soils which often lack oxygen.
A scientist concluded that plants growing in waterlogged soils had an increased chance of showing signs of nitrogen deficiency.
Use your knowledge of active transport to explain this. [2]

4. What is the difference between embryonic and adult stem cells? [1]
Complete the table about the use of stem cells from different sources to replace damaged cells of a patient.
Source of stem cells
One Advantage
One Disadvantage
Embryo
Adult
Therapeutic cloning
Transformed body cells
[4]
Explain why a stomach cell will make the protein pepsin but a skin cell will not [3]
What is the difference between embryonic and adult stem cells? [1]
Some embryonic stem cells were removed from an embryo. Use your knowledge of growth and development in cells to explain the differences in cells produced by processes A and B [6]
An embryo develops from a fertilised egg (zygote) in animals.
All the embryonic stem cells in a zygote are identical to one another.
Put a tick () next to each correct statement.
Embryonic stem cells . . .
are produced by mitosis.
can switch off any gene during development of the embryo.
contain different genes to those found in specialised cells.
contain half the number of chromosomes found in the zygote.
[2]

5. Compare the processes of mitosis and meiosis. [6]
Explain why a fertilised cell contains chromosomes from both parents.
Your answer should include:
What type of cell division produces gametes
What happens to the chromosome number when a gamete is formed
What happens when the gametes fuse [3]
The two main parts of the cell cycle are cell growth and mitosis. Which statements about the cell cycle are true?
Put ticks () in the boxes next to the correct statements.
The nucleus divides during cell growth.
The chromosomes are copied to form new strands of DNA.
The number of organelles in each cell decreases as the cell grows.
The copies of each chromosome stay together when the cells divide during mitosis.
The number of chromosomes doubles in each cell before the cell divides.
Compare the processes of mitosis and meiosis. [6]
Every nucleus in the body cell of a dog contains 78 chromosomes.
Read the statements about cell division in dogs.
Put a tick () in the correct box for each statement.
You should only have one tick in each row. [3]
Meiosis is a type of cell division.
Use ideas about chromosomes to explain how cells made by meiosis are different from those made by mitosis and why this is important. [2]

6. How do auxins affect plant cells? [3]
A scientist investigated the response of plants to light. He put one group in the dark, one group exposed to light from one side and one group in even illumination. The atmosphere contained radioactive carbon dioxide. The scientist measured the amount of radioactive auxin in the area below the shoot tip.
Explain what the results tell the scientist about the effect of light on auxin in the plants.
[4]
A glass jar containing a seedling was placed next to a window. After a few days the tip of the seedling stem had grown towards the window.
Explain how the seedling stem grows towards the light coming through the window. [6]
The tip is removed from a shoot and placed on an agar block for several hours. The agar block is then placed back over the cut end of the shoot and left to grow. Which way will it grow? [1}
How do auxins affect plant cells? [3]
Explain how phototropism increases a plants chance of survival in natural conditions. [2]

7. The graph shows the effect of light intensity on photosynthesis in a single celled plant. Describe and explain the effect of light intensity on the plant. [4]
This is a diagram of a cell from a leaf.
Name and label the structure where photosynthesis takes place. [1]
Define the following terms:
Photosynthesis
Chloroplast
Limiting factor [3]
Explain how the products of photosynthesis are used by the plant. [6]
Write down the balanced symbol equation for photosynthesis. [2]