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11.4 Sexual reproduction

IB Syllabus Statements

Understandings:

  • Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

  • Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm.

  • Fertilization in animals can be internal or external.

  • Fertilization involves mechanisms that prevent polyspermy.

  • Implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy.

  • HCG stimulates the ovary to secrete progesterone during early pregnancy.

  • The placenta facilitates the exchange of materials between the mother and fetus.

  • Estrogen and progesterone are secreted by the placenta once it has formed.

  • Birth is mediated by positive feedback involving estrogen and oxytocin.

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Applications and skills:

  • Application: The average 38-week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

  • Skill: Annotation of diagrams of seminiferous tubule and ovary to show the stages of gametogenesis.

  • Skill: Annotation of diagrams of mature sperm and egg to indicate functions.

Videos

Spermatogenesis

The Sperm and the Egg

The Structure and Function of the Placenta

Avoiding Polyspermy

Animal Size and Duration of Gestation

Oogenesis

What happens after I get pregnant?

Internal vs. External Fertilization

Declining Male Fertility

The Process of Fertilization

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Topic 11.4 Sexual reproduction SSaQ (Syllabus Statement as Questions)

  • Explain how the use of the female contraceptive pill poses risks to human male fertility.

  • Explain the processes of spermatogenesis and oogenesis, including mitosis, cell growth, two divisions of meiosis, and differentiation.

  • Compare the results of spermatogenesis and oogenesis with regard to number of gametes and amount of cytoplasm.

  • Compare internal and external fertilization in animals.

  • Explain the mechanisms that prevent polyploidy in fertilization.

  • Explain the role of HCG during early pregnancy.

  • Explain the importance of the implantation of the blastocyst in the endometrium for the continuation of pregnancy.

  • Outline the role of the placenta, and the hormones secreted by it.

  • Outline the process of positive feedback involving estrogen and oxytocin during birth.

  • Explain where the average 38-week pregnancy in humans would be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

  • Explain how you would annotate diagrams of seminiferous tubule and ovary to show the stages of gametogenesis.

  • Explain how you would annotate diagrams of mature sperm and egg to indicate functions.

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