Overview
What you’ll learn
- State that fertilisation is the fusion of the nuclei of an egg and a sperm, and that heredity passes features to offspring.
- Describe puberty as the stage when the body becomes able to reproduce, with hormones involved but without the hormone system in detail.
- Outline the menstrual cycle, including menstruation when fertilisation does not occur.
- Outline condom, contraceptive pill and sterilisation, and distinguish bacterial STIs from HIV.
- Explain that harmful substances can reach a fetus, and evaluate population and ethical questions using facts.
In 30 seconds
- 1Fertilisation is the fusion of the nucleus of a sperm with the nucleus of an egg.
- 2Heredity means offspring can inherit features from their parents.
- 3Puberty is when the body becomes able to reproduce. Hormones are involved. You do not need the hormone system in detail.
- 4In the menstrual cycle the uterus lining thickens. If fertilisation does not occur, the lining is shed.
- 5Birth control methods to name: condom, contraceptive pill, sterilisation. A condom also reduces the chance of some infections.
- 6Syphilis and gonorrhoea are bacterial and can be treated with antibiotics. HIV is a virus, so those antibiotics do not cure it. Harmful substances in the blood can reach a fetus.
Notes · 1 of 5
Fertilisation and heredity
A new individual starts when two nuclei join. Some features are inherited.
Fertilisation is the fusion of the nucleus of an egg with the nucleus of a sperm. The ovary releases the egg. The testis produces sperm. Fertilisation usually happens in the oviduct. The uterus is where a pregnancy can develop. You need these parts and their jobs, not a labelled diagram of every structure.
Heredity is the passing of features from parents to offspring. Eye colour and blood group are examples of inherited features. Not every difference is inherited: scars and skills are not passed on in the genes.
Notes · 2 of 5
Puberty
The body changes so that reproduction becomes possible later.
Puberty is the stage when a child develops towards being able to reproduce. Hormones cause the changes. You do not need to name glands or draw the hormone system.
- Growth speeds up, and body hair appears.
- In someone born female, periods usually start.
- In someone born male, the voice deepens and sperm production begins.
- The changes do not all happen at the same age. That variation is normal.
Notes · 3 of 5
The menstrual cycle
An outline is enough: lining, possible implantation, or menstruation.
About once a month, the lining of the uterus thickens. It is ready in case a fertilised egg arrives and implants. If fertilisation does not occur, the lining is shed. That bleeding is menstruation, or a period.
Hormones control the cycle. Naming each hormone is not required. The cycle is a sign that the reproductive system is working. It is not an illness.
Notes · 4 of 5
Birth control and infections
Know the outline of three methods, and which infections antibiotics can treat.
| Method | Outline |
|---|---|
| Condom | A barrier. It also reduces the chance of some infections being passed on. |
| Contraceptive pill | A hormone method taken by the person who could become pregnant. It must be used as prescribed. |
| Sterilisation | An operation that is intended to be permanent. |
Sexually transmitted infections pass from person to person during sexual contact. Syphilis and gonorrhoea are caused by bacteria and can be treated with antibiotics. HIV is a virus that can lead to AIDS. Antibiotics do not cure viral infections. Testing and treatment are health care, not something to hide or to attempt alone.
Notes · 5 of 5
Substances, population and ethical questions
Use facts. Set out more than one view. Do not give instructions.
The fetus receives substances from the parent’s blood. Alcohol, nicotine and some other drugs can cross to the fetus and harm its development. Avoiding those substances in pregnancy protects the fetus.
A country may worry about population size because food, housing, jobs and healthcare are limited. That is a reason to study population. It is not a judgement about any one family.
Questions about abortion and about sex before marriage are ethical as well as scientific. A good answer states the facts, then the values on each side: health and circumstances of the people involved, and beliefs about the embryo or about relationships. Science does not order a person what to decide. Do not describe a procedure.
Revise
Key terms
The words examiners expect you to use precisely.
- Fertilisation
- Fusion of the nucleus of a sperm with the nucleus of an egg. It usually happens in the oviduct.
- Ovary
- The organ that releases the egg.
- Oviduct
- The tube where the egg and sperm nuclei usually fuse.
- Testis
- The organ that produces sperm.
- Heredity
- The passing of features from parents to offspring.
- Puberty
- The stage when the body becomes able to reproduce.
Show 7 more key termsShow fewer key terms
- Hormone
- A chemical messenger. Hormones help control puberty and the menstrual cycle.
- Menstruation
- Shedding of the uterus lining when fertilisation has not occurred.
- Uterus
- The organ where the lining thickens and where a pregnancy can develop.
- Birth control
- Methods used to reduce the chance of pregnancy, such as a condom, the pill or sterilisation.
- Antibiotic
- A medicine that can treat bacterial infections. It does not cure viruses.
- HIV
- A virus that can be passed on during sexual contact and can lead to AIDS.
- Fetus
- The developing baby. Substances in the parent’s blood can reach it.
Revise
Common mistakes
Where students most often lose marks in this chapter — and what to do instead.
Mistake: Saying fertilisation is the joining of any two body cells.
It is specifically the egg nucleus and the sperm nucleus.
Instead: Fertilisation is fusion of those two nuclei.
Mistake: Saying antibiotics cure HIV.
HIV is a virus. Antibiotics act on bacteria.
Instead: Antibiotics can treat syphilis and gonorrhoea. They do not cure HIV.
Show 4 more mistakesShow fewer mistakes
Mistake: Describing how a contraceptive is used, or how a procedure is done.
The syllabus asks for an outline and an evaluation, not a method.
Instead: Name the method and its purpose. Stop there.
Mistake: Saying every feature of a child is inherited.
The environment and learning also shape a person.
Instead: Heredity passes biological features such as blood group. Scars and skills are not inherited.
Mistake: Calling menstruation an illness.
It is part of the cycle when fertilisation has not occurred.
Instead: The lining is shed. That is a normal process.
Mistake: Telling the reader what they must decide about abortion or relationships.
The mark is for facts and for setting out the ethical question.
Instead: State both sides. Do not preach.
Check yourself
Quick quiz
10 questions with instant explanations. About 5 minutes.
Question 1 of 3
- Question 1: current question
- Question 2: not answered
- Question 3: not answered
Define fertilisation
Fertilisation is the fusion of
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Practise
Topical questions
Exam-style practice in three tiers, from recall to data questions.
- 5Foundation
- 5Standard
- 5Challenging
15 questions worth 35 marks, each with a model answer, mark scheme and examiner tips.
Practise topical questionsExam practice
Practice paper
A 30-mark paper set out like a school paper, with a separate mark scheme. Give yourself 40 min.
Question paper
Chapter 8 Practice Paper
30 marks · 40 min · 6 pages
10 multiple-choice questions and structured questions with answer lines. Chapter 8.
Mark scheme
PROChapter 8 Practice Paper — mark scheme
Answers · Marking points · 3 pages
Model answers with a mark for each creditworthy point — for marking at home or in class.
Where this chapter is tested
Each school sets its own scope — check your assessment outline.
Questions
Frequently asked questions
What is fertilisation in Sec 2 Science?
The fusion of the nucleus of a sperm with the nucleus of an egg.
What should I know about the menstrual cycle?
The uterus lining thickens. If fertilisation does not occur, the lining is shed. That is menstruation. Hormones control the cycle, but you do not need each hormone named.
Which birth-control methods should I be able to outline?
Name the condom, the contraceptive pill and sterilisation, and say how each reduces the chance of pregnancy. A condom can also reduce the chance of some infections being passed on. Stop at that outline.
Why do antibiotics not cure HIV?
Syphilis and gonorrhoea are caused by bacteria, so antibiotics can treat them. HIV is a virus. Antibiotics do not cure viruses.
Is reproduction in the Sec 2 EOY?
Most schools that follow the usual G2/G3 scheme teach this chapter in Sec 2 and include it in the Sec 2 end-of-year paper. A few schools move a topic across the two years, so check your school’s assessment outline.