CIE iGCSE Co-Ordinated Science B1.1 Characteristics of living organisms Exam Style Questions Paper 4
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B15.3 — Sexual reproduction in plants (Parts (a), (b))
• Topic B15.1/B15.2 — Asexual and sexual reproduction (Part (c))
• Topic B1.1 — Characteristics of living organisms (Part (d))
▶️ Answer/Explanation
(a)(i) Fertilisation: C; Pollen produced: B
C is the carpel/stigma region leading to the ovule where fertilisation occurs.
B is the anther where pollen grains are produced.
(a)(ii) Feathery, exposed stigma (E); anthers hanging outside the flower (B/C).
A feathery stigma increases surface area to catch airborne pollen.
Anthers hanging loosely outside the flower allow pollen to be released easily into the wind.
(b) Wind-pollinated pollen is smoother (not spiky); wind-pollinated pollen is smaller.
Insect-pollinated pollen (Fig. 1.2) is spiky/sticky to attach to insect bodies.
Wind-pollinated pollen lacks these spikes and is lighter/smaller so it can be carried by air currents.
(c)(i) Sexual reproduction increases genetic diversity; allows adaptation to a changing environment.
Genetic variation means a disease is unlikely to wipe out all the plants.
Variation also allows natural selection/evolution to occur, helping the species adapt.
(c)(ii) Asexual reproduction is useful when the plant is isolated from other plants or pollinators are scarce.
\(\text{No mate/pollinator needed for asexual reproduction}\)
This allows rapid colonisation of a favourable habitat without depending on pollination.
(d) Any two of: movement, respiration, sensitivity, growth, excretion, nutrition.
Movement is a change of position caused by the organism.
Respiration releases energy from nutrients in cells.
Excretion removes waste products of metabolism.
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B12.1 — Respiration (Parts (a), (b) — aerobic vs anaerobic respiration, yeast)
• Topic B1.1 — Characteristics of living organisms (Part (c))
▶️ Answer/Explanation
(a)(i) Sugar C
Table 4.1 shows sugar C produced the largest volume of gas, 82 cm³, in 2 hours.
This is higher than sugars A, B, D and E.
(a)(ii) 0.075 cm³/min
2 hours must be converted to minutes: \(2 \times 60 = 120\) minutes.
Rate \( = \dfrac{9}{120} = 0.075 \, \text{cm}^3/\text{min}\).
(a)(iii) Carbon dioxide
Anaerobic respiration in yeast produces ethanol and carbon dioxide.
The gas collected and measured in this investigation is carbon dioxide.
(a)(iv) Bread making (or any named practical use)
In bread making, carbon dioxide produced by yeast causes dough to rise.
Other accepted uses include brewing alcoholic drinks.
(b) Any three differences (aerobic vs anaerobic respiration in humans)
Aerobic respiration requires oxygen, while anaerobic respiration does not.
Aerobic respiration releases more energy per glucose molecule than anaerobic respiration.
Aerobic respiration produces carbon dioxide and water, whereas anaerobic respiration in humans produces lactic acid instead.
(c) Any one other characteristic of living organisms
Accepted characteristics include movement, sensitivity, growth, reproduction, excretion, and nutrition.
Any one of these, besides respiration, is a valid answer.