Sexual reproduction 11.4 HL

Sexual reproduction in this HL topic begins with spermatogenesis and oogenesis where gametes are made. This is followed by the process of fertilisation, the acrosome reaction and the cortical reaction. The development and implantation of a blastocyst in the endometrium of the uterus is important as well as the hormones which change during pregnancy finally leading to positive feedback and birth. There is a lot of content in this topic.

Key concepts

Learn and test your biological vocabulary using these 11.4 Sexual reproduction flashcards

What you need to know

These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - great revision.

Read the slides and look up any words or details you find difficult to understand.

Main points

Summary list for 11.4 Sexual reproduction

Gametogenesis

  • Similarities in spermatogenesis and oogenesis include mitosis, cell growth, two divisions of meiosis and differentiation.
  • Students need to be able to annotate diagrams of seminiferous tubule and ovary to showing these details.
  • Differences between the processes in spermatogenesis and oogenesis are the different numbers of gametes produced and the different amounts of cytoplasm in these gametes.
  • Annotation of diagrams of mature sperm and egg to indicate functions.

Fertilization

  • Fertilization in animals can be internal or external.
  • Fertilization involves the acrosome reaction, fusion of the plasma membrane of the egg and sperm and the cortical reaction (mechanisms that prevent polyspermy).

Early growth of the embryo

  • 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.

Skills & applications

  • To make comparisons of gestation periods and animal size & to find the place of the average human (38-week) pregnancy on a graph showing the correlation between animal size and the development of the young at birth in mammals.
  • To annotate diagrams of stages of gametogenesis in seminiferous tubule and an ovary.
  • Ability to annotate diagrams with the function of the parts of mature sperm and egg.

Mindmaps

These diagram summaries cover the main sections of topic 11.4 about sexual reproduction.
Study them and draw your own list or concept map from memory.

Exam style questions

Sexual reproduction

Understanding the structure of mature sperm cells and the placenta are both important steps in understanding their function in this topic. Many students learn the names or all the parts of a sperm.

This question helps to practise explaining the functions of these parts.

Answer this question on a piece of paper, then check your answer against the model answer below.

Describe the structure and function of a sperm cell. [5]

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Test yourself

Multiple choice questions

This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.


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