1. Gamete Oogenesis Spermatogenesis Fertilisation 2. Label ...sciencestephenson.com/wp-content/uploads/2018/07/... · 7/11/2018 · Essential Biology 6.6 & 11.4 Reproduction Core

Essential Biology 6.6 & 11.4 Reproduction Core & AHL Due Date:

Stephen Taylor Bandung International School http://sciencevideos.wordpress.com

1. Define the following:

Gamete

Oogenesis Spermatogenesis Fertilisation Gestation

2. Label the structures of the mature sperm and egg and calculate the magnification of each

image.

a

b

c

d

e

f Magnification:

g

Magnification:

http://sciencevideos.wordpress.com/



3. Label this diagram of the male reproductive system.

a

b

c

d

e

f

g

h

4. Annotate this light micrograph of testis tissue.




5. State the roles of the following hormones in spermatogenesis.

Luteinizing hormone (LH)

Testosterone

Follicle stimulating hormone (FSH)

6. State three other roles of the male sexual hormone testosterone.

7. Outline the process of spermatogenesis in the testes.

8. Outline the role of the following structures in semen production.

epididymis

seminal vesicle

prostate gland




9. Label this diagram of the female reproductive system.

Annotate each structure with its function.

a.

b.

c.

d.

e.

f.

Name these structures:

g

10. Label and annotate these structures of the ovary.

a

b

c

d e f

11. Outline oogenesis.




1.

2.

3.

4.

12. Compare spermatogenesis and oogenesis.

Spermatogenesis Oogenesis

Number of gametes produced per primary cell

Formation of gametes

Number of meiotic divisions

Method of release of gametes

Number of gametes released

Hormones used

Location




13. Outline the roles and origins of these menstrual cycle hormones.

Follicle Stimulating Hormone (FSH) Origin: pituitary gland (brain)

Role: -

Luteinzing Hormone (LH) Origin:

Role:

- )

Oestrogen Origin: ovary

Role: -

Progesterone Origin

Role: -

14. State the role of these two hormones in the female reproductive system.

HCG:

Oxytocin

Deduce the hormones and events required to complete this concept map.




15. The graph below shows the human menstrual cycle.

a. Sketch the changes in the endometrium over the cycle.

b. Outline the events of the menstrual cycle, including the roles of the various hormones.

1-4 Days Follicular phase

Events: − Menstruation

− FSH increases, causing development of follicle

5-14 Days Ovulatory phase

Events: − FSH and the developing follicle stimulate oestrogen release

− Oestrogen stimulates endometrium development

− Oestrogen stimulates LH

− LH peaks at day 14, causing ovulation

14-28 Days Luteal phase

Events: − Fall in LH

− Corpus luteum forms from empty follicle

− Corpus luteum releases progesterone

− Progesterone maintains the endometrium and inhibits FSH and

LH




16. Distinguish between fertilisation and pregnancy.

− Fertilisation is fusion of sperm and ovum nuclei

− Pregnancy is the development of the foetus

17. Describe the process of fertilization of an egg by a sperm.

acrosome reaction

When the head of the sperm contacts the zona pellucida, the acrosome of the sperm releases enzymes to loosen the zona pellucida so it can wiggle in to touch the egg membrane

Fusion of sperm and egg membrane

The plasma membrane of the sperm has proteins allowoing it to bind with egg membrane, releasing the sperm nucleus

Cortical reaction

Fusion of sperm with egg activates the egg, causing it to release the contents of the cortical granules by the egg membrane to cause the zona pellucida to become an impenetrable fertilization membrane to prevent polyspermy

18. The contraceptive pill manipulates the hormones of the menstrual cycle in order to prevent

unwanted pregnancy.

a. The combined pill contains oestrogen and progestin (a synthetic form of progesterone).

Explain how this combination might prevent pregnancy.

− Prevents menstruation

− Cycle does not repeat

− Follicle does not develop so there is no ovulation b. The package of pills usually contains 21 pills of the hormone and 7 ‘placebo’ pills. These

placebo pills can contain an iron supplement. Deduce the function of these pills.

− Allows menstruation to occur to shed endometrium

− Prevents anaemia

19. The ‘rhythm method’ is used in family planning and contraception.

Identify the days of the cycle during which a woman is:

a. Most likely to conceive

− Around day 14 (between days 8 -19)

b. Least likely to conceive.

− During menstruation (days 1-7)

− Before menstruation (days 20-28)




20. Evaluate the following methods of contraception.

Effectiveness for… Contraception Protection against STI’s

Oral contraceptive pill

99.7% 0%

Rhythm method

91% 0%

Condoms

85-98% (depending on how carefully it is used)

85-99%

21. Outline the process of in-vitro fertilisation.

1 FSH and LH are given in high doses to the potential mother in order to stimulate production of multiple ova.

2

Eggs are collected

3 Eggs fertilized with father’s sperm in a dish and incubated

4 Viable blastocysts are selected and developed into embryos

5 Up to 3 embryos are selected for implantation (risk of multiple)

6 Bed rest for 1 month then pregnancy test is carried out

If pregnancy does not occur, some of the “extra” embryos can be implanted for a 2nd try.




22. Discuss the ethical issues of IVF.

Arguments for Arguments against

- Right to have children - Improving medical technology

makes it safer than ever before - Some governments will cover

costs - Hope for those who cannot have

children by traditional means - Unused embryos can be stored

and used later, donated or as a source of stem cells

- Religious (are doctors playing God?)

- The risk to the mother and children of multiple pregnancies

- Extreme costs - Emotional cost of failure - Extra hormonal load - Is the termination of extra

embryos killing a human?

Reading: IVF Wins Nobel Prize for Medicine 2010!

http://nobelprize.org/nobel_prizes/medicine/laureates/2010/press.html

23. HCG is released early in the pregnancy if a blastocyst implants on the endometrium.

a. State the origin of HCG.

b. Outline two functions of HCG in early pregnancy.

Function Advantage

Inhibits… FSH and LH

Maintains…

c. HCG can be detected in the urine. Identify the type of immune system molecule

used to detect HCG in pregnancy kits.

Immunoassay d. State the method used to produce these molecules for the test kits.


http://nobelprize.org/nobel_prizes/medicine/laureates/2010/press.html



24. Early embryonic development.

a. State the method of cell division used in embryonic development.

Mitosis b. Outline the events leading up to implantation of the blastocyst on the endometrium.

Cell division Cilia beat to move the blastocyst down the oviduct towards the uterus

25. The developing fetus is protected and served by the placenta, amniotic sac and umbilical cord.

State the function of the amniotic sac and fluid.

Support and shock absorption

Identify the hormones released by the placenta.

hCG

List the materials exchanged between the fetal and maternal blood.

Mother to fetus:

- Amino acids, lipds, glucose - Water - Vitamins and minerals - Oxygen - Antibodies

Fetus to mother:

- Carbon dioxide - Urea/waste - Water - hCG

26. Explain how the following structures of the placenta aid its function.

Umbilical cord

connects the foetus to the placenta and maternal blood pools via open ended arterioles into intervillous spaces (lacunae)

Villi

Chorionic villi extend into intervillous spaces and facilitate the exchange of materials between the maternal blood and fetal capillaries

Inter-villus spaces Filled with maternal blood

Blood supply

Transports nutrients, oxygen and antibodies to the foetus, and carbon dioxide and waste products away from the foetus

Membrane Cells that separate maternal and foetal blood

Rough endoplasmic reticulum in cells







27. Birth is controlled by positive feedback mechanisms in the body, which is in contrast to the

negative feedback mechanisms of homeostasis.

a. State the name of the ‘birth hormone’.

oxytocin

b. Explain why regulation of this hormone is classed as positive feedback control.

Presence of oxytocin in blood stimulates the release of more oxytocin

c. Outline the process of birth and its hormonal control.

- Progesterone levels drop - Fetal head engages in cervix - Switch receptors stimulate pituitary gland to release oxytocin - Oxytocin initiates contractions in myometrium - Contractions stimulate further release of oxytocin (positive feedback),

making contractions stronger and more frequent - Cervix dilates, allowing baby to be born through vagina - Contractions continue to expel the placenta - Umbilical cord is clamped and cut - Breast feeding encourages oxytocin, stimulating contractions to return

uterus to normal size - Contractions against an empty uterus causes oxytocin levels to drop

Links across the syllabus:

• How do sexual reproduction and meiosis ensure variation in the population?

• How does the oxygen in the maternal blood get into the fetal blood?

• What similarities are there between the structures of the placenta and other human body

systems?

• How are twins produced and how does polygenic inheritance lead to variation in some

characteristics (e.g. skin colour) between non-fraternal twins?

• How does gene expression lead to differences in the phenotypes of fraternal twins, despite their

sharing DNA?

• What is prenatal testing and how is it applied in pregnancy?

• What are the risks of late-age pregnancy?

How many more links across the syllabus can you find and explain?




Works Cited 1. Taylor, Stephen. 6.6 Reproduction Core (Presentation). Science Video Resources. [Online] Wordpress, December 2010. http://sciencevideos.wordpress.com.

2. Allott, Andrew. IB Study Guide: Biology for the IB Diploma. s.l. : Oxford University Press, 2007. 978-0-19-915143-1.

3. Mindorff, D and Allott, A. Biology Course Companion. Oxford : Oxford University Press, 2007. 978-099151240.

4. Clegg, CJ. Biology for the IB Diploma. London : Hodder Murray, 2007. 978-0340926529.

5. Campbell N., Reece J., Taylor M., Simon. E. Biology Concepts and Connections. San Fransisco : Pearson Benjamin Cummings, 2006. 0-8053-7160-5.

6. Burrell, John. Click4Biology. [Online] 2010. http://click4biology.info/.

7. IBO. Biology Subject Guide. [Online] 2007. http://xmltwo.ibo.org/publications/migrated/production-app2.ibo.org/publication/7/part/2/chapter/1.html.

8. —. IB Biology QuestionBank 1st Edition. [CD-Rom] Oxford, UK : IBO, 2005. http://store.ibo.org/product_info.php?products_id=1224.


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1. Gamete Oogenesis Spermatogenesis Fertilisation 2. Label ...sciencestephenson.com/wp-content/uploads/2018/07/... · 7/11/2018 · Essential Biology 6.6 & 11.4 Reproduction Core