Question

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SECTION A (approx. 1 hour). Answer on the special MCQ answer sheet provided. Follow the instructions carefully on how to fill this in. Answer ALL questions. ERRE 1. Which germ layer is found in triploblastic animals but not diploblastic animals? a) Ectoderm b) Endoderm c) Mesoderme d d) Mesoglea er 2. At which developmental stage should one be able to first distinguish a protostome embryo from a deuterostome embryo? a) Fertilization b) Cleavage c) Gastrulation d) Coelom formation 3. Which of the following are NOT a major class within the Mollusca? a) Gastropods b) Bivalves c) Cephalopods d) Rotifers 4. What is the main function of the notochord? a) Skeletal support b) Conducting nerve impulses c) Digestion d) Nitrogen excretion 5. Why is the amniotic egg considered an important evolutionary breakthrough? a) It has a shell that increases gas exchange. b) It allows deposition of eggs in a terrestrial environment. c) It prolongs embryonic development. d) It provides insulation to conserve heat. 6. Population growth is described by the logistic growth curve: dN=CN (kN) where N population size, - carrying capacity and c is the growth constant. The maximum number of elephants a National Park can support is 100, the current population is 50 strong. Assuming that the growth constant. c, equals 1, the increase in elephants in the next generation will be a) 50 b) 25 c) 100 d) 10

Answer 1

1. Mesoderm is found in Triploblastic animal, not in Diploblastic animal. While ectoderm and endoderm are found in both cases.

2. At Cleavage stage, one will be able to distinguish between Protostome embryo and Deuterostome embryo, as both are 8 cells during cleavage, but Protostomes are Spiral and determinate whereas Deuterostomes are Radial and indeterminate.

3. Rotifers as it belongs to Platyzoa.

4. The main function of Notochord is Skeletal support.

5. The amniotic egg is considered as an important evolutionary breakthrough because it allows deposition of eggs in a terrestrial environment.

6. Increase in population in next-generation is 25.