Csec Mock 2019.docx

SECTION A Answer ALL questions. Write your answers in the spaces provided in this booklet.

1.

A student investigating transpiration carried out the following procedure. He obtained two celery stalks and cut the bottom end of each while they were submerged in water. The cut ends of both stalks were then quickly placed in two flasks of dye, Flask A and Flask B. Flask A was placed on a laboratory bench in normal room conditions, while flask B was put in the same room but warm air from a blow-dryer was directed onto it. The time was noted and the celery stalks were allowed to stand for 30 minutes. The students measured and recorded the distance the dye had travelled up each stalk at five-minute intervals during the 30-minute period. The results are shown in Table 1. TABLE 1: DISTANCE DYE TRAVALLED UP THE CELERY STALKS Time (minutes)

(a)

(i)

Stalk A (distance in cm)

Stalk B (distance in cm)

5

1

2

10

3

4

15

5

8

20

7

12

25

9

15

30

10

17

On the grid paper provided, draw a line graph to represent the data shown in Table 1. (4 marks)

(ii) Account for the differences in the shape of the line graphs for Stalks A and B. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… (2 marks) (b)

Write a suitable aim for this experiment. ……………………………………………………………………………………………… ……………………………………………………………………………………………….. (2 marks)

(c)

Which flask represent the control in this experiment? ……………………………………………………………………………………………… (1 mark)

(d)

What conclusion can be drawn from this data? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………. (2 marks)

(e)

Describe the physical processes involved in the movement of water from the soil into the plant roots, up the stem and out through the leaves. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (4 marks)

(f)

Describe TWO ways in which the xylem is adapted from transporting water within a flowering plant. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………….. (2 marks)

(g)

Suggest THREE ways in which transpiration benefits the plants. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (3 marks)

(h)

Name a type of transport tissue, OTHER THAN XYLEM, found in flowering plants and state the composition of the fluid transported in this tissue. ……………………………………………………………………………………………… ………………………………………………………………………………………………. (2 marks)

(i)

Outline ONE difference and TWO similarities between the transport system of flowering plants and that of mammals.

Difference………………………………………………………………………………......... Similarities……………………………………………………………………………………. …………………………………………………………………………………… (3marks) Total 25 marks

2. (a) The following chemical equation for photosynthesis represents the reactants used and the products formed. 6CO2 + H2O → (i)

C6H12O6 + O2

Name TWO conditions, which are NOT shown in the equation, that are essential for this process. ……………………………………………………………………………………… ……………………………………………………………………………………… (2 marks)

(ii)

Name the gas given off in the process and state which of the reactants produce this gas. Gas…………………………………………………………………………………… Reactant……………………………………………………………………………… (2 marks)

(iii)

Explain TWO ways in which plants utilize the glucose produced during this process. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… (4 marks)

(iv)

State THREE environmental factors which affect photosynthesis. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… (3 marks)

(b)

Unlike plants, animals are unable to synthesize glucose. A boy eats a meal of cassava. Explain how his body converts the starch in the cassava to glucose. Name the organs and the enzymes involved in this process. ……………………………………………………………………………………………… ……………………………………………....……………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (4 marks) Total 15 marks

3.

Figure 1 is a diagram of the human female reproductive system.

Figure 1. Structure of the human female reproductive system (a) Label the organs in Figure 1 to show where: (i) the female gametes (ova) are made

(1 mark)

(ii)

fertilization would normally occur

(1 mark)

(iii)

implantation of a fertilized gamete would normally occur

(1 mark)

(b) Outline the mechanism by which male and female gametes come together in the human reproductive system to form a zygote. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… (3 marks) (c) (i) Name the type of cell division by which female gametes are made.

…………………………………………………………………………………………… (1 mark)

(ii) Describe Two ways in which the type of cell division named in (c) (i) differs from that by which the embryo grows and develop after fertilization of an ovum. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… (4 marks)

(d) Embryonic stem cells are undifferentiated cells formed as the embryo grows and develops. These cells are capable of differentiating into specialized cells of tissues and organs in the human body. (i)

Suggest TWO reasons why cell specialization is important. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… (2 marks)

(ii)

Explain why embryonic stem cells can be used in the treatment of physiological disease. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… (2 marks) Total 15 marks

SECTION B Answer ALL questions in this section. Write your answers in the spaces provided in this booklet. 4.

(a)

(i)

Explain why food chains usually begin with a plant species. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… (2 marks)

(ii)

Using an appropriate diagram, show how a plant or animal may belong to more than one food chain.

Space for 4. (a) (ii)

(4 marks)

(iii) Explain why the number of organism decreases at the successive trophic level. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………….…………………………………………………………… …………………………………………………………………………………… (2 marks) (b)

Biological control usually involves the introduction of new species to an ecosystem to reduce or control the population of organisms considered to be pests. (i)

Identify ONE relationship that is important in biological control and explain how this relationship functions in biological control. ……………………………………………………………………….……… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (3 marks)

(ii)

Suggest TWO reasons why biological control is a preferred method of reducing pest populations compared to the use of pesticides. ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (4 marks) Total 15 marks

5.

(a)

Using annotated diagrams, compare the structure of an unspecialized plant cell with that of an unspecialized animal cell.

Space for 5. (a)

(6 marks) (b)

Nerve cells become specialized to carry out their function. Suggest THREE features of a nerve cell which enable it to carry out its function effectively. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… …………………………………………………………………………………………. (3 marks)

(c)

Cell specialization is one mechanism that allows an organism to carry out its functions efficiently. Another mechanism that allows an organism to function effectively is the adaptation to its habitat. (I)

Identify TWO physical factors which animals encounter (face) in an aquatic habitat, such as a freshwater pond. ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (2 marks)

(iii)

Suggest TWO adaptations that animals in freshwater ponds might have. Explain how EACH adaptation is useful to the animal. ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (4 marks) Total 15 marks

6.

Albinism is seen in persons who are homozygous for the recessive allele of a certain gene. This gene codes for the production of the skin pigment, melanin. Persons who inherit the dominant allele of this gene produce the normal amount of melanin for their race. (a)

Distinguish between the following paired terms: allele/gene; dominant/recessive; homozygous/heterozygous. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… (6 marks)

(b)

(i)

Use a genetic diagram to show how a couple with normal pigmentation may produce an albino child. Use the following symbols to represent the alleles: A- normal; a- albino. ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (5 marks)

(ii)

Suggest TWO precautions that albino persons living in the Caribbean should take when going outdoors. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… (2 marks)

(c)

Observation of the members of population shows that there is variation in skin colour. Suggest THREE ways by which this type of variation could occur.

…………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… (2 marks) Total 15 marks

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