Question 1

The diagram below shows two flowers from the same plant. Which of the arrows show(s) pollination taking place?

Accepted Answer

B. W and Y only. Pollination is the transfer of pollen grains from the anther (male part) to the stigma (female part) of a flower. Arrow W shows transfer within the same flower (self-pollination) and arrow Y shows transfer to the stigma of another flower on the same plant (also self-pollination). Arrow X goes from stigma back to anther, which is not pollination.

Question 2

The diagram below shows the movement of blood in some parts of the human circulatory system. Which of the above blood vessels carry blood that is richer in carbon dioxide?

Accepted Answer

B. A and C. Blood returning from the body parts (head and legs) to the heart is rich in carbon dioxide. Arrow A shows blood flowing from the head to the heart, and arrow C shows blood flowing from the heart to the lungs (which still carries carbon dioxide to be released). B carries oxygen-rich blood from lungs and D carries oxygen-rich blood to the body, so they are not correct.

Question 3

Which of the following takes place in plants but not in humans?

Accepted Answer

A. The fertilised egg is found in the ovary.. In plants, after fertilisation the fertilised egg (zygote) remains inside the ovary of the flower and develops into a seed. In humans, the fertilised egg develops in the womb, not the ovary. Options C and D occur in both organisms (humans have testes; plants have stamens producing pollen which fuses with the egg).

Question 4

Study the picture below. Tom used water that was used to wash fruits to water the plants in his garden. What method(s) of water conservation is/are involved?

Accepted Answer

B. reducing and reusing. Using the same water for two purposes (washing fruits, then watering plants) is reusing the water. Because the second use replaces water Tom would otherwise have drawn fresh from the tap, he is also reducing his overall water use. No treatment/cleaning step occurs, so it is not recycling.

Question 5

Study the table below. Which of the following is a correct conclusion?

Accepted Answer

D. Substance X has a higher freezing point than substance Y.. From the table, X stays solid at all three temperatures up to 85 °C, so its freezing/melting point is above 85 °C. Y is still solid at 45 °C but liquid at 85 °C, so its freezing point is between 45 °C and 85 °C. Therefore X has a higher freezing point than Y. We cannot conclude Y's exact melting point (only that it's between 45–85 °C), and Z boils between 45–85 °C while Y's boiling point is unknown but higher than 85 °C, so option B and C are wrong.

Question 6

Abdul took a glass of cold milk from the refrigerator and placed it on a table in the kitchen at room temperature. Which of the following would he observe after 20 minutes?

Accepted Answer

C. Water droplets on the outside of the glass with water on the table around the glass.. The cold surface of the glass cools the warm water vapour in the surrounding air, causing condensation. Water droplets form on the OUTSIDE of the glass (not inside the lid, since the milk is cold and not evaporating). As more droplets form and trickle down, they collect as water on the table around the glass.

Question 7

Plants lose water through tiny openings on both the upper and lower surfaces of their leaves. These tiny openings are called stomata. Some surfaces of leaves on a plant were coated with oil. The plant was placed in a field with bright sunlight. The volume of water loss after three hours was recorded in the table below. Based on the results in the table, which of the following is a correct conclusion about the stomata on the leaves?

Accepted Answer

A. There are more stomata on the lower surface.. Leaf R (upper surface coated, so only lower stomata open) lost 25 cm³. Leaf T (lower surface coated, so only upper stomata open) lost only 10 cm³. Since more water was lost through the lower surface than the upper, there must be more stomata on the lower surface.

Question 8

The diagram below shows the movement of substance Q, gases X and Y, to system P and also to other human organ systems. Which of the following best represents P, Q, X and Y?

Accepted Answer

D. P: circulatory system, Q: digested food, X: carbon dioxide, Y: oxygen. System P receives digested food from the digestive system and gases from the respiratory system, then distributes them — this is the circulatory system. Gas X moves from system P to the respiratory system (so it is carbon dioxide being exhaled). Gas Y moves from the respiratory system to P (so it is oxygen being absorbed into the blood). Substance Q is digested food.

P5 Science SA1 2021 — Tao Nan

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