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11.4 Sexual reproduction

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Description

Nature of science:
Assessing risks and benefits associated with scientific research—the risks to human male fertility were not adequately assessed before steroids related to progesterone and estrogen were released into the environment as a result of the use of the female contraceptive pill. (4.8)
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.
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.
Guidance:
  • Fertilization involves the acrosome reaction, fusion of the plasma membrane of the egg and sperm and the cortical reaction.
 Utilization:
Syllabus and cross-curricular links:
Biology
Topic 3.3 Meiosis
Topic 6.6 Hormones, homeostasis and reproduction

Aims:
  • Aim 8: Disputes over the responsibility for frozen human embryos.

Directly related questions

Sub sections and their related questions

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