2017 GCE O Level Bio Suggested Answer Final (Edited FPE 20

2017 GCE O Level Biology Suggested Answer Paper 1 1 2 3 4 5 6 7 8 9 10 C A A D B D C B B C 11 12 13 14 15 16 17 18 19 20 A A C B C A C B A A 21 22 23 24 25 26 27 28 29 30 D D B C A A B A B D 31 32 33 34 35 36 37 38 39 40 B C A C C A C D A B Paper 2 (Section A) 1 (a) Define Homeostasis is the maintenance of a constant internal environment through the mechanism of negative feedback. (b) Explain the term Endocrine glands are ductless glands that secrete their hormones directly into the bloodstream [1]. The adrenal gland is an example of an endocrine gland. It secretes adrenaline directly into the bloodstream to be transported to target organs. [1] Other endocrine glands and their secretions: - Ovary → oestrogen and progesterone - Testis → Testosterone - Pituitary gland → ADH - Pancreas → Islets of Langerhans secrete insulin and glucagon Questions to note: 6, 15, 20, 24, 35 Question to note: 3b, 5b, 7biv, 9b, 10

(c) (i) Name A: glycogen [1] B: glucagon [1] (ii) Explain During exercise, muscle cells obtain energy through the processes of respiration (aerobic & anaerobic), where glucose is broken down to release energy [1]. The supply of glucose is obtained from the bloodstream and hence this causes a fall in the blood glucose concentration [1]. 2 (a) Suggest C is the intercellular air space which allows air to be trapped so that the water lily is buoyant/can float on the water surface [1]. (b) State reason The palisade cells are situated right below the upper epidermis so that they can capture maximum amount of sunlight for photosynthesis [1]. (c) State role Chlorophyll absorbs light energy [1] and converts it to chemical energy during photosynthesis [1]. The chemical energy formed is used to synthesise carbohydrates from carbon dioxide and water.[1] (d) 3 (a) Explain The banana plant is the producer as it can make its own food via photosynthesis. It is also the first organism in the food chain and provide the rest of the organisms in the food chain with energy and oxygen [1].

(b) (c) 4 (a) Describe The mass of each pot of plant should be measured at the start of the experiment using an electronic balance and then measured at the same time over the next 10 days [1]. The loss of mass is calculated by subtracting the current measured mass from the mass measured on the previous day [1]. (b) Name Transpiration [1]. (c) Suggest Plant D would lose the most mass. Reason Plant D has more leaves and therefore more stomata than plant F which allows for greater loss of water vapour to the environment [1]. Plant D is not enclosed in a plastic bag like plant E , so humidity is lower and rate of transpiration is higher. [1] (d) Suggest This is to prevent loss of water from the soil due to evaporation or respiration of organisms in the soil [1].

5 (a) Define Asexual reproduction is