chap 5 bio f5 (module)

7/29/2019 Chap 5 Bio F5 (module)

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CHAPTER 4 : REPRODUCTION AND GROWTH

4.1 Analysing gamete formation1. Necessity to reproduce

(a) To ensure the ________________ of the species

(b) To ensure the passing down of an individuals _________ to future generation

2. Necessity for the formation of gametes(a) To ensure the _________________________ number is maintained from one generation to the next

(b) The ________________________ in the offspring enable them to adapt to constantly changing environment

(c) To ensure the survival of the species

3. Types of reproduction

4. Male reproductive systemStructure Function

Produce male gametes (sperm) and male sex

hormones

Where sperms are stored and mature

Transport sperms from epididymis to ejaculatory duct

Secrete a thick, clear fluid containing nutrients for the

sperms

Secrete a milky white fluid that activates or increases

the mobility of the sperm

Exit route for sperm and urine

COMPARISON

No formation of Involved formation of

The process relies entirely on ... division Gamete are formed by . division

Involves only individual (single parent) Involve parents

New individual get their genes from one parent

without the .. of an egg and sperm

New individuals inherit genes from both parents

through the .

Produces offspring that are genetically ...

to the parent

Produce offspring that are genetically

from their parents

Ensure that the adaptation of the parent for survival

are passed down unchanged to the offspring if the

environment is stable

Ensure the survival of the species if the environment

condition undergo changes constantly

Asexual

Reproductive process in

which new individuals are

produced without the

formation of gametes

Sexual

Production of offspring

through the fusion of haploid

gametes to formed a diploid

zygote (fertilised egg)

Head Large nucleus and acrosome (contain hydrolytic enzymes)

Acrosome digest protective layer of ovum

Middle piece Large number of mitochondria

Provide energy for movement of the tail

*Sperms are immotile when they are first formed. Sperms absorbed

nutrients in the epididymis and become active and motile.Tail Locomotion and movement


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Formation of sperm in humans Spermatogenesis (spermatozoa formation) takes place in in seminiferous tubules The process takes 65 to 75 days in human male

Sertoli cells provide nutrients to spermatids

Leydig cells produce androgen and testosterone

5. Female reproductive system

Formation of ovum in humans

Spermatogenesis

Cross section of seminiferous tubule


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Com parison between the formation of sperm and o vaSpermatogenesis Oogenesis

Similarities

Both processes occur in the _______________________

Both involved the process of _________________

Both produce _____________ gametes

Differences

Gametes produced

Place of formation

Size of gametes

Number of gametes produced

during meiosis

Equal distribution of cytoplasm in all four

sperm cell producedCytokinesis

Unequal, with almost cytoplasm contained in

the secondary oocyte and ovum while the

small polar bodies degenerate

Has a head, midpiece and a tail Shape of gametes Spherical

Divide by mitosis throughout the adult life of

men after pubertyGerminal epithelial cells

Divide by mitosis during foetal stage. At

birth, an ovary contains all the primary

oocyte that will develop into ova

Occurs continuously and does not stop at any

stageMeiotic division

Does not occur continuously, stop atProphase I and Metaphase II

Meiosis II completes only if secondaryoocyte is fertilised by a sperm

4.2 Analysing the role of hormones in menstrual cycle1. Menstrual cycle the cyclic changes that occur in the endometrium of the uterus to prepare it for a fertilised ovum

and its subsequent development.

2. Hormones involved in a menstrual cycle;Hormones that control the changes in the ovaries Hormones that control the changes in the uterus

Hormones FSH LH Oestrogen ProgesteronePlace of

secretion

The anterior lobe of

pituitary gland

The anterior lobe of the

pituitary gland

Follicle cells of the ovary Corpus luteum

Function

Stimulates thedevelopment and

growth of follicles

Stimulates thefollicles in ovary to

secrete oestrogen

Stimulates ovulation Stimulates the

development of

corpus luteum

Promotes secretionof progesterone

Stimulates furthergrowth of follicle

Promotes repair andgrowth of

endometrium

Low level inhibitsFSH and LH (-ve)

High level stimulatesFSH and LH (+ve)

Stimulates theendometrium to

become thick, folded

and highly vascular

for the implantation

of embryo

High level inhibitsthe secretion of FSH

and LH

Menstruation : the breakdown of the lining of the uterine wall and the discharge of blood, epithelial tissues and mucus through vagina

Menstrual cycle divided into three main phase menstrual, proliferative and secretory phase First day of menstruation = first day of menstrual cycle

Days Hormonal control of the menstrual cycle

0 to 7 1. A day before menstruation, GnRH (hypothalamus) stimulates the release of FSH and LH2. FSH stimulates the ___________________________________3. The cells of developing follicles secrete ___________________4. _________ oestrogen level FSH and LH level __________ (-ve feedback)5. As the maturing follicle enlarge, more amount of oestrogen secreted.

8 to 14

(proliferative

and

ovulation)

6. 12th day levels of oestrogen rise steeply and peak7. Increase of oestrogen exerts +ve feedback on hypothalamus and pituitary gland8. Increase of GnRH stimulates a rise in the secretion of ________ and ________ (peak at 13th day)9. Level of progesterone still low

15 to 21 10. The corpus luteum secretes smaller amount of oestrogen but larger amount of ___________________11. Oestrogen and progesterone ____________ the secretion of FSH and LH (-ve)12. Oestrogen and progesterone stimulates the ________________ to become thicker, more folded and highly vascular in

preparation for the implantation of fertilised ovum.


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22 to 28

(secretory)

13. Iffertilisation not occurs, _______________________ start to disintegrate.14. Disintegration of ________________________ cause the level of oestrogen and progesterone to __________15. Thus, endometrium breaks down and disintegrates (menstrual flow)16. Reduced level of _______________, no longer inhibit the hypothalamus and pituitary gland17. GnRH released, stimulates the release of FSH and LH18. New cycle starts with development of new follicle.19. Iffertilisation occurs, corpus luteum will not ____________________20. Level of oestrogen and progesterone continue to _____________21. Endometrium continue to grow and nourish embryo22. 3 months after fertilisation, corpus luteum degenerates, production of oestrogen and progesterone is taken over by the

placenta

23. Progesterone inhibits FSH and LH, no ovulation and menstrual cycle during pregnancy.

Premenstrual syndrome (PMS) Physical and psychological symptoms which

some women experience 5 to 10 days before

menstruation

The causes are not known but could be due to

imbalance in oestrogen and progesterone

level

Symptoms : water retention, painful cramp in

uterus, headaches, backaches, joint pains,

changes in mood, depression, anxiety,

irritability, sleepy and lethargy

Menopause Cessation of monthly menstruation, end of a

womans fertility period

Occurs between 45 to 55 years old when

ovaries are less stimulated by FSH and LH

Inhibits development of follicles and

ovulation, low level of progesterone and

oestrogen

Menstrual cycle stop, ovaries stop produce

ova

Low level of oestrogen contribute to decrease

in bone density

Symptoms : hot flushes, night sweats,

migraine headache, mood swings, depression,

lethargy, bodily changes and increased risk of

osteoporosis.


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4.3 Understanding the early development of zygote in humans1. Fertilisation(a) A sperm penetrates the plasma membrane of a secondary oocyte(b) Once the sperm succeeds in entering the secondary oocyte, meiosis II is completed.(c) Ovum and second polar body are formed.(d) Fertilisation membrane forms on the surface of the oocyte to prevent other sperms entering the ovum.(e) The sperm discards its tail and its nucleus moves towards the ovums nucleus.(f) Fusion of sperm an ovum formed diploid nucleus(g) Fertilised ovum is called zygote.

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4.4 Appreciating the contribution of science and technology to human reproduction4.5 Synthesising the concept of sexual reproduction in flowering plant4.6 Understanding growth in multicellular organisms4.7 Understanding the growth curve4.8 Understanding primary and secondary growth in plants

chap 5 bio f5 (module)

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