Topic 9:REPRODUCTION & DEVELOPMENT Part 3

Topic 9: REPRODUCTION & DEVELOPMENT Part 3

Fertilisation & foetal development

Roles of hormones during pregnancy & parturition

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FIGURE shows fertilisation process that occurs in a human female.

Where does fertilisation process normally takes place?

FIGURE shows fertilisation process that occurs in a human female.

Stages of fertilisation in human.

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FIGURE shows fertilisation process that occurs in a human female.

State the ploidy level of a sperm.

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Name the FOUR stages of fertilisation in human.

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How does the secondary oocyte prevent the penetration of more than one sperm?

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Why is it important that only one sperm enters the secondary oocyte?

4 STAGES THAT LEAD TO FERTILIZATION

• 1. Capacitation

• 2. Acrosomal reaction

• 3. Fusion of sperm head membrane & oocyte

• 4. Cortical reaction

Multiple Choice

Arrange the CORRECT sequence of fertilisation processes.

●1) Capacitation releasing hydrolytic enzymes.

●2) Sperm passes between follicle cells and arrives at jelly coat (zona pellucida) of secondary oocyte.

●3) New nucleus divide by mitosis immediately forming diploid cells (2n).

●4) Haploid (n) nuclei from egg nucleus and sperm nucleus fuse.

●5) Head of sperm engulfed by plasma of secondary oocyte.

●6) Cortical granules of outer layers of cytoplasm of secondary oocyte pass across plasma membrane to prevent entry of another sperm.

●7) Hydrolytic enzyme digestion creates helps sperm to reach plasma membrane of secondary oocyte.

●8) Nucleus of secondary oocyte stimulated to complete meiosis II by arrival of male nucleus.

• 1 2 7 5 6 8 4 3

• 2 1 7 6 5 4 8 3

• 2 1 7 5 6 8 4 3

• 1 2 7 6 5 4 8 3

Multiple Select

Explain how contraceptive pills containing progesterone prevents pregnancy.

• High level progesterone acts as inhibitor / exerts negative feedback

• Stimulates secretion of FSH by anterior pituitary gland

• Thus no follicles develop and no ovulation takes place

• Zero chance of fertilization leading to pregnancy

Human fertilisation & foetal development

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Label process I, II, III and IV.

Multiple Choice

Which of the following is the CORRECT sequence in the development of a human zygote?

• Zygote - Embryo - Morula - Blastocyst

• Zygote - Morula - Blastocyst - Embryo

• Zygote - Blastocyst - Morula - Embryo

• Zygote - Morula - Embryo - Blastocyst

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Name human hormone involved in the function described.

Control menstrual cycle and pregnancy; inhibit ovulation.

Stimulates development of mammary (milk) glands in breasts to prepare for lactation

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Name human hormone involved in the function described.

Control testes and ovaries; triggers ovulation.

Stimulates final maturation of follicle (forming Graafian follicle)

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Name human hormone involved in the function described.

Stimulates contraction of uterus at birth.

Ejaculation of milk during breast feeding @

Stimulates contraction of smooth muscles surrounding mammary glands (forces milk through milk ducts and nipple) -controlling release of milk.

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Name human hormone involved in the function described.

Spermatogenesis; stimulates development and maintenance of male secondary sexual characters

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Name human hormone involved in the function described.

Dilates the cervix; relaxes the pelvic ligaments.

Enhance contractions of uterus muscles.

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Name human hormone involved in the function described.

Control menstrual cycle and pregnancy; stimulates development and maintenance of female secondary sexual characters.

Stimulates development of mammary (milk) ducts in breasts to prepare for lactation.

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Name human hormone involved in the function described.

Stimulates milk secretion by lactifenous ducts.

Stimulates mammary glands (alveoli) and produce milk.

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Name human hormone involved in the function described.

Stimulates the development of a Graafian follicle in an ovary.

Multiple Select

Compare between flowering plant and human reproductive systems.

Similarities:

• Involved male and female organs (for flowering plants)

• Involved male or female organs (for humans)

• Diploid zygote (2n)

• Both involved sexual fertilisation in reproductive systems

• Zygote grows into embryo

Multiple Select

Compare between flowering plant and human reproductive systems:

Differences;

• Female gamete is egg produced in ovule while female gamete is egg produced in ovary.

• Pollen nuclei fuses with egg nuclei (fertilization) while sperm nuclei fuses with egg nuclei (fertilisation)

• Embryo grows inside protective seed coat while embryo grows inside protective womb

• Cotyledons provide nourishment while placenta provide nourishment.

Multiple Select

Differences between fertilization events in flowering plants & mammals.

• Flowering plants: Male gamete is non-motile whereas Mammals: male gamete (sperm) is motile.

• Flowering plants: The entire process of meiosis has completed and the female gamete is already formed before fertilization whereas Mammals: Ovum (female gamete) is formed upon penetration of sperm into secondary oocyte, whereby secondary oocyte completes meiosis II.

  Fertilization occurs when the gametes (sperm & ovum) fuse.

• Flowering plants: Double fertilization occurs. Two male nuclei are involved. One sperm (n) fuses with the female gamete (n) to form the diploid (2n) zygote while the other one sperm (n) fused with the two polar nuclei (n+n) to form triploid (3n) endosperm cell whereas Mammals: Only one fission occurs between the sperm nucleus (n) and the ovum nucleus (n) to form a diploid (2n) zygote.