Temasek Sec 2024_Prelim_4E_BIO_ANS

1 Temasek Secondary School 6093 Biology Prelim 2024 Answers PAPER 1 (40 marks) No Answer No Answer 1 C 21 D 2 A 22 C 3 B 23 B 4 D 24 C 5 B 25 D 6 C 26 A 7 B 27 B 8 B 28 C 9 A 29 B 10 B 30 D 11 C 31 C 12 C 32 B 13 C 33 D 14 D 34 C 15 B 35 B 16 D 36 B 17 A 37 B 18 A 38 C 19 D 39 A 20 C 40 C

2 6093 Biology Prelim 2024 Answers Paper 2 Answers Qn Answer Remarks 1a Insect pollination; Large petals REJECT: colourful petals / scent / nectar guides / compact stigma Both for 1 m bi A sepal / calyx B petal / corolla C fruit / ovary D style Any error deducts 0.5 m bii E produces the pollen biii Circle and name the stigma. [1] (structure tip of style) Both are female parts that receive the male gametes or pollen which contain male gametes. [1] OWTTE 2a Smoking. Cigarette smoke contains tar that can cause uncontrolled cell division Both points 1 m b • Tumor / lumps of cells blocks the alveolar wall / alveolar space / alveoli / bronchiole space / makes the alveolar wall less elastic / less able to inflate/ deflate / reduces surface area of alveoli [1] • This reduces the volume in the lungs [0.5] and increases pressure in the lungs. [0.5] / Decreases the surface area for gaseous exchange / diffusion hence lower rate of diffusion of gaseous [1] • During inhalation, less air can be forced into the lungs / during exhalation less air can flow out of the lungs / there will be breathing difficulty [1] c Patient has a slower rate of fat digestion by lipase [1] due to less / little bile released into gall bladder hence duodenum. [0.5] Lesser / no emulsification of fats can occur. SA:V of fat droplets / globules remain low. [0.5]

3 Qn Answer Remarks d Non-infectious as it cannot be spread from person to person and not caused by pathogens 3a Voluntary as the action is controlled consciously / by choice / initiated by her b Nerve impulse initiated in her brain [0.5] Transmitted via the relay neurone [0.5] from the brain to the spinal cord [0.5] In the spinal cord the nerve impulse is transmitted across a synapse to the motor neurone [0.5] The motor neurone transmits the nerve impulse to the bicep muscles [0.5] Bicep muscles contract to move her arm to lift the tool [0.5] c Any one: Water pollution: There will not be any insecticides / fertiliser in the nearby water bodies reducing / no / less water pollution / cleaner water [0.5] • So no bioaccumulation and biomagnification [0.5] of non-biodegradable substances up the food chain, [0.5] top consumers are not harmed [0.5] • No eutrophication / algal bloom / growth of algae will occur [0.5] so no death/decomposition of water plants by bacteria, no increase in bacterial growth [0.5] thus no oxygen depletion in water / water continues to have high oxygen [0.5 ] Biodiversity: Insects in the ecosystem/ habitat not killed by insecticide