Biology Paper 02 Practice Exam

Paper 2 · Structured · 32 questions · 100 marks

1 (a) (i)A class in Antigua places cowpea seeds on moist cotton wool in two stoppered test tubes, P and Q. Tube P is kept in a cupboard at 28 °C and tube Q is kept in a refrigerator at 4 °C. Write a suitable aim for this experiment.
[2 marks]
1 (a) (ii)Cowpea seeds are placed on moist cotton wool in tube P, kept at 28 °C, and tube Q, kept at 4 °C. In which tube, P or Q, are the seeds most likely to germinate? Give ONE reason for your answer.
[2 marks]
1 (a) (iii)In an experiment on germination, cowpea seeds were placed on moist cotton wool. State TWO roles that water from the cotton wool plays in the germination of the seeds.
[2 marks]
1 (b) (i)The cowpea seedlings that germinated are placed on a windowsill in a classroom. Light enters only through the window on one side, and after four days the shoots are all bending towards the window. What type of movement is shown by the shoots?
[1 mark]
1 (b) (ii)Cowpea seedlings on a windowsill receive light from one side only, and their shoots bend towards the window. State a hypothesis that could be tested using this set-up.
[2 marks]
1 (b) (iii)Cowpea seedlings on a windowsill bend towards light coming from one side. Suggest how the students could change the set-up so that the seedlings grow straight upwards.
[1 mark]
1 (b) (iv)The cowpea seedlings have used up all the food stored in their cotyledons. Discuss the process by which the young plants are now able to make their own food.
[4 marks]
1 (b) (v)Young cowpea plants need raw materials to make food in their leaves. Discuss the processes by which these raw materials reach the leaves of the plant.
[4 marks]
1 (c) (i)Starch is the main storage carbohydrate made in the leaves of green plants. Describe a test the students could carry out in the laboratory to find out whether starch is present in a leaf from one of the cowpea seedlings.
[4 marks]
1 (c) (ii)Apart from leaves, name ONE plant organ in which starch may be stored.
[1 mark]
1 (c) (iii)Animals do not store starch. Instead, they store the complex carbohydrate glycogen. Name TWO organs in the human body that store glycogen.
[2 marks]
2 (a)A classification key based on the Whittaker five-kingdom system works as follows. Living organisms are first divided by the type of cell they have. Organisms with cells that have no true nucleus are placed in Kingdom Monera, for example cyanobacteria; these cells are described as P. Organisms with a true nucleus are divided by their number of cells: unicellular organisms belong to Kingdom Protista, for example Q, and organisms made of many cells are described as R. These are then divided by whether their cells have a cell wall. Those without a cell wall belong to Kingdom S, for example the frog. Those with a cell wall are divided by type of nutrition: heterotrophs belong to Kingdom Fungi, for example bread mould, and autotrophs belong to Kingdom T. Give the correct word or example for each of P, Q, R, S and T.
[5 marks]
2 (b) (i)In classification, each kingdom is divided into smaller and smaller groups, the smallest being the species. Define the term 'species'.
[2 marks]
2 (b) (ii)A Great Dane and a Chihuahua look very different, yet both are domestic dogs. Using domestic dogs as an example, explain why physical appearance (morphology) is NOT always useful for deciding whether organisms belong to the same species.
[2 marks]
2 (b) (iii)Suggest ONE reason why biologists prefer to use the biological concept of species (the ability to interbreed) rather than physical characteristics when classifying organisms.
[2 marks]
2 (c) (i)After a hurricane, a small group of iguanas floated on a raft of fallen trees from St Vincent to a distant uninhabited cay. Many generations later, scientists classified the cay iguanas as a new species. Using the biological concept of a species, state TWO reasons why they were reclassified.
[2 marks]
2 (c) (ii)On the cay, the new species of iguana living in the dry coastal scrub was found to be smaller than the same species living in the moist inland forest. Suggest TWO reasons for this variation.
[2 marks]
3 (a) (i)During a 28-day human menstrual cycle, the level of hormone J rises steadily from day 5 as a follicle develops in the ovary and peaks at about day 12. At about day 14, event K takes place. After event K, the level of hormone L rises, reaches its highest level at about day 21 while a corpus luteum is present, and then falls before the next menstruation. Identify hormone J, event K and hormone L.
[3 marks]
3 (a) (ii)In the menstrual cycle, oestrogen peaks before ovulation and progesterone peaks about one week after ovulation. What is the role of EACH of these hormones in the menstrual cycle?
[2 marks]
3 (a) (iii)Name the structure that produces oestrogen and the structure that produces progesterone during the menstrual cycle.
[2 marks]
3 (a) (iv)During the menstrual cycle a corpus luteum forms in the ovary after ovulation, and the lining of the uterus is thick. Discuss what happens to the corpus luteum and to the uterus lining if the ovum is fertilised.
[4 marks]
3 (b)Some contraceptive pills taken by women contain hormones such as oestrogen and progesterone. Suggest how these pills may prevent pregnancy.
[1 mark]
3 (c)Scientists in the Caribbean are researching a contraceptive pill for men. Suggest THREE ways in which such a pill could prevent pregnancy.
[3 marks]
4 (a) (i)Explain how structures in the human eye control the amount of light that enters the eye in bright light and in dim light.
[4 marks]
4 (a) (ii)During a power cut in Kingston, Marcus walks into his dim kitchen. He can make out the shapes of the table and chairs, but he cannot tell their colours until the electricity comes back on. Explain why Marcus can see the shapes of objects in the dim kitchen but cannot see their colours until the lights come on.
[5 marks]
4 (b)Red-green colour blindness is caused by a recessive allele carried on the X chromosome, so it is described as sex-linked. A woman with normal colour vision, whose father is colour-blind, has children with a man who has normal colour vision. Use Xᴮ for the allele for normal vision and Xᵇ for the allele for colour blindness. Using a genetic diagram, work out the chance that any one of their children will be colour-blind.
[6 marks]
5 (a)A student in Grenada eats a lunch of rice (carbohydrate) and fried fish (protein and fat). Describe the chemical digestion of the carbohydrate, protein and fat in this meal from the mouth until the products are absorbed in the small intestine.
[6 marks]
5 (b) (i)After a meal, glucose is absorbed in the small intestine. Describe how the body systems work together so that the glucose is assimilated.
[4 marks]
5 (b) (ii)A 15-year-old in Barbados has type 1 diabetes, and his friend does not have diabetes. Explain how the way the friend's body handles glucose after a meal differs from that of the person with diabetes.
[5 marks]
6 (a)Using a suitable example of EACH, distinguish between a predator-prey relationship and parasitism.
[6 marks]
6 (b) (i)In the 1990s, the pink hibiscus mealybug damaged crops and trees in several Caribbean islands. Instead of spraying chemical pesticides, some islands released a tiny wasp that attacks the mealybug. Outline THREE advantages and THREE disadvantages of this method of biological control compared with the use of chemicals.
[6 marks]
6 (b) (ii)A wasp has been introduced to control the pink hibiscus mealybug. Explain how this biological control may contribute to evolution by natural selection in the mealybug population.
[3 marks]