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Gametogenesis-Human Cycle Memo GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE Life Sciences/P1 9 DBE/Feb.–Mar. 2018 NSC SOURCE: NSC, FEB/MARCH 2018, P1 2.2 Diagrams I anD II below represent gametogenesis in human males anD females (not in any particular sequence). The Diagrams are NOT Drawn to scale. Meiosis I 1 1 Meiosis II 3 2 Degenerating cells Diagram I Diagram II 2.2.1 Identify the specific type of gametogenesis in Diagram I. (1) 2.2.2 Explain your answer to QUESTION 2.2.1 by referring to a visible difference between Diagram I anD Diagram II. (2) 2.2.3 Where in the human boDy Does the type of gametogenesis shown in Diagram II take place? (1) 2.2.4 Give the chromosome number of: (a) The cells at 1 (1) (b) Cell 2 (1) 2.2.5 Name TWO processes that take place During Meiosis I that leaD to genetic variation in the four cells shown at 3 in Diagram II. (2) 2.2.6 Explain the implication for the human population size if the three cells referreD to in Diagram I did not degenerate, but remained as gametes. (2) (10) ! 2.2.7 Briefly describe the type of gametogenesis that occurs in diagram II. (5) (15) Copyright reserveD Please turn over GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE MEMO 2.2.7! - Cells of the germinal epithelium ✓ (diploid spermatogonium) in the testis ✓ ! of the male !- undergoes meiosis ✓ !- Four immature sperms (spermatids) are formed ✓ !- They then develop to become mature sperms (spermatozoan) ✓!! (5) (15) GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE SOURCE: PRELIM, FREE STATE 2018, P1 GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE MEMO 2.2.1 (a) Testes (b) Ovum 2.2.2 ! Prostate gland Cowper's glands Seminal vesicles (any 2) (MARK 1ST TWO ONLY) 2.2.3! Corpus luteum 2.2.4! - It maintains the endometrium - It inhibits the release of FSH /LH - to prevent the development of any other follicles /to prevent ovulation 2.2.5! - Enzymes from the acrosome of the sperm/ digest / penetrate the - outer jelly like layer of the ovum - The head of the sperm penetrates the ovum - The haploid nucleus of the sperm cell fuses - with the haploid nucleus of the ovum - forming a diploid zygote (any 4) (12) Life Sciences P1/Grade 12 9 September 2017 GAMETOGENESIS,SECTION B FERTILIZATION & HUMAN CYCLE QUESTION 2 SOURCE: PRELIM, CLUSTER 2017, P1 2.1 The diagram below represents stages in the life cycle of a mammal. The number of chromosomes in cells at different stages in the life cycle are shown. Study the diagram and answer the questions that follow. MALE FEMALE PARENTS 36 36 R 18 18 18 18 18 18 18 18 GAMETESGGGAME S 36 2.1.1 Name the type of cell division represented by R in the diagram. (1) 2.1.2 State where in the male body the process mentioned in QUESTION 2.1.1 takes place. (1) 2.1.3 Identify the process represented by S in the diagram. (1) 2.1.4 If the sex chromosomes are the same as in humans, how many autosomes would be present in one of the female gametes in this mammal? (1) 2.1.5 Explain ONE significance of crossing over which occurs during process R in the diagram. (2) 2.1.6 Draw and label a chromosome to show its appearance after crossing over takes place. (3) (9) Copyright reserved Please turn over GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE MEMO 2.1.1!Meiosis 2.1.2!Testis / seminiferous tubules 2.1.3!Fertilsation 2.1.4!17 2.1.5! - Genetic material is exchanged - bringing about variationin the gametes 2.1.6! A chromosome MARKING CRITERIA • A double stranded chromosome joined by a centromere • Evidence of crossing over is visible/there are shaded and not shaded portions • Any one correct label (9) GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE Life Sciences/P1 8 DBE/November 2018 NSC SOURCE: NSC, NOV 2018, P1 1.4 The diAgrAm below represents A sequence of events thAt mAy tAke plAce inside the humAn femAle reproductive system. I II A B C 1.4.1 Identify the process tAking plAce At I in the diAgrAm above. (1) 1.4.2 StAte the type of cell division thAt tAkes plAce At II in the diagrAm above. (1) 1.4.3 NAme TWO functionAl extrA-embryonic membrAnes thAt Are produced by structure C. (2) 1.4.4 Identify the stAge of development indicAted by: (a) A (1) (b) B (1) (c) C (1) 1.4.5 NAme the pArt of the femAle reproductive system where the events in the diagrAm above usuAlly tAke plAce. (1) 1.4.6 Give the chromosome number of the cell at A if this cell is going to develop into A child with Down syndrome. (1) (9) MEMO 1.4.1! Fertilisation 1.4.2! Mitosis 1.4.3! Chorion Amnion 1.4.4!(a)! Zygote !(b)! Morula !(c)!Blastula 1.4.5! Fallopian tube /oviduct 1.4.6! 47 (9) Copyright reserved PleAse turn over GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE Life Sciences P1/Grade 12 17 September 2017 SECTION C SOURCE: PRELIM, CLUSTER 2017, P1 QUESTION 4 Describe the process of oogenesis as it takes place in the female body. Also describe the functions of the two hormones produced by the ovaries including their role in the body during puberty. Content: (17) Synthesis: (3) (20) NOTE: NO marks will be awarded to answers in the form of tables, flow charts or diagrams. TOTAL SECTION C: 20 GRAND TOTAL: 150 MEMO Oogenesis in female body - Under the influence of FSH - diploidcells - in the ovary - undergo mitosis - to form numerous follicles/primary oocyte - One cell inside a follicle enlarges and undergoes meiosis - Of the four cells that are produced, only one cell survives - to form a mature haploid ovum (Any 5) Hormones of the ovaries Oestrogen Produced by the Graafian follicles in the ovaries - Causes the lining of the uterus/endometrium - to become thicker/more vascular - in preparation for a possible implantation of the embryo and development of the foetus During puberty oestrogen stimulates: - The widening of the pelvis/hips - The growth and development of the breasts - The growth of the female sex organs - The start of the menstrual cycle, ovulation and menstruation (Any 7) Copyright reserved Please turn over GAMETOGENESIS, FERTILIZATION & HUMAN CYCLE Progesterone Produced by the corpus luteumin the ovaries - Progesterone causes further thickening of the endometrium - so that it is ready for implantation of the embryo should fertilisation occur - High levels of progesterone - inhibits the secretion of FSH - by the pituitary gland - which in turn prevents the further development of any new ovum in the ovaries (Any 5) ASSESSING THE PRESENTATION OF THE ESSAY Criterion Relevance (R) Logical sequence (L) Comprehensive (C) Generally All information Ideas are arranged in a All aspects required by provided is relevant to logical/cause-effect the essay have been the question. sequence. sufficiently addressed. In this essay All information Oogenesis is described At least the following provided relates to: in a sequential manner marks have been - Oogenesis and the role of the obtained: - Oestrogen hormones oestrogen - Oogenesis (3/5) - Progesterone and progesterone are - Oestrogen (5/7) There is no irrelevant described separately. - Progesterone (3/5) information. Mark 1 1 1 TOTAL SECTION C: 20 GRAND TOTAL: 150.
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