CSEC Biology Paper 2 May/June 2021 - Free CXC Past Paper with Answers

Name the TWO raw materials and state the TWO conditions that are necessary for photosynthesis.

Figure 1 is a drawing of a leaf. On the grid provided on page 5, make a drawing of the leaf that is twice the size of Figure 1.

On the diagram drawn on page 5, label EACH of the following parts of the leaf: apex, lamina, midrib, petiole.

The leaf shown in Figure 1 on page 4 is from a plant that grew in very windy conditions. Suggest ONE way in which the leaf is adapted for EACH of the following functions: (i) Gaseous exchange (ii) Preventing excess water loss

Preventing excess water loss

Green plants can produce food by photosynthesis. Suggest THREE reasons why there is still a need for them to store food.

Suggest THREE reasons why the initial carbohydrate product of photosynthesis (glucose) is not stored in green leaves.

Describe the test that could be used to determine if a green leaf has stored starch.

Unlike plants, animals must ingest complex food substances then break these down by mechanical and chemical digestion. Explain TWO ways in which the human digestive system is adapted for the mechanical digestion of food.

Define the term 'pollination'.

Describe how male gametes reach female gametes in humans.

Figure 2 shows the female part of a flower in which the petals, sepals and stamens have been removed. Label EACH of the following parts on the diagram: stigma, style, ovary and ovule.

Explain why a human embryo does NOT have large nutrient stores but a plant embryo does.

Suggest FOUR reasons why a couple would be advised to use the permanent method of birth control for the male rather than the permanent method of birth control for the female.

Figure 3 is a diagram of a terrestrial food web.

Figure 3. Terrestrial food web

Using the food web illustrated in Figure 3, identify a (i) producer (ii) predator (iii) primary consumer.

State TWO roles of the producer in the food web.

Identify ONE biotic factor and ONE abiotic factor that would affect the organisms shown in Figure 3. (i) Biotic (ii) Abiotic

Explain why there are fewer organisms at the top than at the bottom of the food web.

Discuss TWO possible consequences of the hawk becoming extinct in the eco-system shown in Figure 3.

Suggest TWO reasons why decomposers are important organisms in all food webs.

SECTION B Answer ALL questions.

Figure 4 is a labelled diagram of a nephron.

Figure 4. Diagram of a nephron

Use Figure 4 to describe how urine is formed.

Explain why there is a high concentration of glucose in the urine of a diabetic patient.

State ONE similarity and TWO differences between the method by which the human body regulates blood sugar levels and the method by which the human body regulates the amount of water in the blood.

Suggest TWO ways in which kidney damage can be prevented in diabetic and hypertensive patients.

Red and white blood cells are important components of human blood. Use clearly labelled diagrams to illustrate the structure of a red blood cell and the structure of a white blood cell.

Red blood cell

White blood cell

Explain how any TWO features of a red blood cell ensures that it is suitable for its major function in the human body.

The ABO blood grouping system is determined by antigens on the surface of red blood cells. An individual who has one parent with the heterozygous genotype for blood group A and the other parent with the heterozygous genotype for blood group B may have a blood group (phenotype) that is different from either parent. With the aid of a genetic diagram, explain how an individual may have a blood type that is different from either parent.

Outline Darwin's theory of natural selection.

Explain why the developing of antibiotic resistance by bacteria is considered to be an example of natural selection.

A farmer wishes to use artificial selection to alter the characteristics of his crops. Suggest TWO ways in which artificial selection will benefit the farmer.

A species of toad which carry a toxin was introduced on an island which was inhabited by iguanas. The iguanas mainly forage. Many but not all of the iguanas died when they ate the toads. Several years later biologists examined the iguanas for any changes and observed that the length of the tails of the adult iguanas increased by ten per cent.

Suggest THREE possible reasons for the increase in tail length observed in these iguanas.

One of the biologists suggested that the iguanas with longer tails were a new species, but another biologist argued that a species is not determined by different physical features. Provide an explanation to support this conclusion.

Describe TWO situations which may lead to the evolution of a new species.

CSEC Biology Paper 2 May/June 2021 Questions

Question 1 (25 marks)

Question 2 (15 marks)

Question 3 (15 marks)

Figure 3. Terrestrial food web

Question 4 (15 marks)

Figure 4. Diagram of a nephron

Question 5 (15 marks)

Question 6 (15 marks)