H1 Bio WA2 (Teacher)

1 Civics Group Index Number Name (use BLOCK LETTERS) ST ANDREW’S JUNIOR COLLEGE 2022 JC2 Weighted Assessment 2 H1 BIOLOGY 8876 STRUCTURED QUESTIONS 30 minutes READ THESE INSTRUCTIONS FIRST Write your name, civics group and index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagram, graph or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. All working for numerical answers must be shown. Conceptual error (C) Data Quoting (D) Expression (E) Misreading the question (Q) For Examiner’s Use STQ 1 /9 STQ 2 /11 Total /20 This document consists of 5 printed pages. [Turn over H1

2 QUESTION 1 The diagram below represents the various birth weights of new -born calves in a wild population of deer in the African grasslands. The line graph on the diagram represents mortality in relation to birth weight. Fig. 1 (a) Using the information provided in Fig. 1 (quote data from the graph), account for (state and explain) the mode of selection acting on birth weight of new-born deer calves. ………………………………………………………………………………………………. [3] 1 Stabilising selection; 2 Calves with extreme birth weights lower than 5.5 kg or more than 9.5 kg [Accept 4.5-5.5kg, and 9.0-10.0kg] have high mortality of >5%, [Accept 3-7%, according to quoted data] and are hence selected against / have lower reproductive success. 3 Calves with intermediate birth weight of 5.5 to 9.5 kg have mortality rate of < 5%, and are hence selected for / have higher reproductive success. (b) Birth weight of new-born deer calves is an example of continuous variation (#TB to continuous/discontinuous variation under the topic of genetic basis of variation). Explain why there is a variation of birth weights in the population of deer. (Suggest 4 causes of continuous variation) ………………………………………………………………………………………………. [4] 1 Spontaneous mutations; lead to formation of new alleles / genetic variation in the population. 2 During prophase I, crossing over occurs between homologous chromosomes, the formation of new combinations of alleles on the chromosomes of the gametes; 3 During metaphase I/ II, independent assortment of homologous chromosomes/ chromatids, resulting different combinations of maternal and paternal chromosomes; Intermediate phenotype at high frequency due to low mortality%

3 4 Random fusion of gametes during fertilization, giving rise to new combinations of alleles in the offspring. 5 Effect of polygenes (birth weights affected by cumulative effects of different genes); OR Additive effects of multiple alleles; 6 Ref. to environmental factors affecting phenotype (c) Suggest why percentage of mortality is higher on both ends (explain the cause of death for both extremes) of the range o