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(A) The Diagram Below in Figure 5 Represents The Sequence of Events That Occur

The document discusses cell division and meiosis. It includes: 1. The cell cycle diagram labels the longest phase as interphase and lists the stages of cell division as interphase, mitosis, and cytokinesis. 2. During oogenesis in females, primary follicles undergo partial meiosis I and develop into mature follicles encouraging ovulation at puberty. 3. Genetic crosses can be used to determine offspring genotypes and phenotypes based on parental genotypes. While mutations can cause minor changes leading to disease.

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Lorenzini Grant
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70 views2 pages

(A) The Diagram Below in Figure 5 Represents The Sequence of Events That Occur

The document discusses cell division and meiosis. It includes: 1. The cell cycle diagram labels the longest phase as interphase and lists the stages of cell division as interphase, mitosis, and cytokinesis. 2. During oogenesis in females, primary follicles undergo partial meiosis I and develop into mature follicles encouraging ovulation at puberty. 3. Genetic crosses can be used to determine offspring genotypes and phenotypes based on parental genotypes. While mutations can cause minor changes leading to disease.

Uploaded by

Lorenzini Grant
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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1.

(a) The diagram below in Figure 5 represents the sequence of events that occur
in the cell cycle.

cell division

cytokinesis

Cell
Cell
cycle
cycle

Figure 5 . the cell cycle

With reference to the diagram shown in Figure 5. State the event with:

(i) Longest phase

(ii) Outline the stages involved in cell division in the cell cycle :
[4 marks]

(b) During development of the female gametes in a process called oogenesis, primary
follicles are produced which undergo partial completion of meiosis I until puberty,
which will then continue meiotic division to a point which then develop into mature
Graafian follicles encouraging ovulation.

(i) Explain what is meant by ‘homologous pairs’ of chromosomes [1 mark ]

(ii) The primary follicles in the ovary develop in the female foetus in pregnancy to
the point of Prophase I of meiosis until puberty.

Draw an annotated diagram showing the stage of Prophase I of meiosis of the


developing the primary follicles. [4 marks]

(iii) Draw a diagram of the ovum at the point of ovulation. State the chromosome
number of the ovum at this point. [3 marks]

(iv) Describe TWO events that occur in meiotic division that encourages genetic
variation in organisms. [4 marks]

Total 15 marks
2. (a) Explain the difference between ‘gene’ and ‘allele’ [4 marks]

(b) Mary has the genotype (Bb) that codes for black hair and her husband has the
genotype (bb) that codes for brown hair.

Using a genetic cross diagram, determine the ratio at which their offspring will
obtain black hair vs. brown hair. [5 marks]

(c) (i) Define the term ‘mutation’ [ 1 mark]

(ii) Using a named example, explain how minor changes in the genetic sequence
can contribute to disease. [5 marks]

Total 15 marks

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