Homeostasis and response – GCSE AQA Higher Biology revision notes

What this topic covers

Homeostasis and response has 4 subtopics:

• Homeostasis
• The human nervous system
• Hormonal coordination in humans
• Plant hormones (biology only)

Homeostasis and response lessons by subtopic

22 lessons, grouped by subtopic.

Homeostasis

• What is Homeostasis and Why is it Important?: Understand the definition of homeostasis and explore the key conditions that need to be controlled in the human body, including blood glucose, body temperature, and water levels.
• How Control Systems Work in Homeostasis: Discover the three key components of all homeostatic control systems: receptors that detect changes, coordination centres that process information, and effectors that bring about responses.

The human nervous system

• Structure and Functions of the Brain: Explore how the brain controls complex behaviour through billions of interconnected neurones. Learn to identify and describe the functions of the cerebral cortex, cerebellum and medulla using brain diagrams.
• Investigating and Treating Brain Disorders: Examine how neuroscientists map brain functions through studying brain damage, electrical stimulation and MRI scanning. Understand the challenges of investigating brain function and treating brain damage and disease.
• Structure of the Eye: Learn about the key structures of the eye and their functions, including the retina, optic nerve, sclera, cornea, iris, ciliary muscles, and suspensory ligaments. Understand how the eye functions as a sense organ with receptors sensitive to light intensity and colour.
• Accommodation and Light Adaptation (Part 1/2): Explore how the eye focuses on near and distant objects through accommodation, involving the contraction and relaxation of ciliary muscles and changes in lens shape. Also learn about how the eye adapts to dim light conditions.
• Accommodation and Light Adaptation (Part 2/2): Explore how the eye focuses on near and distant objects through accommodation, involving the contraction and relaxation of ciliary muscles and changes in lens shape. Also learn about how the eye adapts to dim light conditions.
• Vision Problems and Corrections: Understand common eye defects including myopia and hyperopia, how they affect vision, and the various treatments available including spectacle lenses, contact lenses, laser surgery, and lens replacement. Learn to interpret ray diagrams showing these defects and their corrections.
• Temperature Detection and Control: Learn how the body monitors and detects temperature changes through the thermoregulatory centre and temperature receptors in the skin.
• Temperature Regulation Mechanisms: Explore how the body responds to temperature changes through vasodilation, vasoconstriction, sweating and shivering to maintain constant body temperature.

Hormonal coordination in humans

• Adrenaline: The Fight or Flight Hormone: Explore how adrenaline is produced by the adrenal glands during stress or fear, and learn how it prepares the body for 'fight or flight' by increasing heart rate and boosting oxygen and glucose delivery to vital organs.
• Thyroxine: Metabolism and Feedback Control: Discover how thyroxine from the thyroid gland controls basal metabolic rate and supports growth and development, and understand how thyroxine levels are regulated through negative feedback mechanisms.
• Hormonal methods of contraception: Understanding how hormonal contraceptives work, including oral contraceptives that inhibit FSH production and slow-release progesterone methods such as injections, implants and patches that prevent egg maturation and release.
• Non-hormonal methods of contraception: Exploring barrier methods, intrauterine devices, spermicidal agents, natural family planning through abstinence timing, and surgical sterilisation methods for both males and females.
• Evaluating contraceptive methods: Comparing and evaluating the effectiveness, advantages and disadvantages of different hormonal and non-hormonal methods of fertility control to make informed decisions about contraception.
• Male and Female Reproductive Hormones: Explore the main reproductive hormones in males and females, including testosterone and oestrogen, and understand how they control puberty and the development of secondary sex characteristics.
• The Menstrual Cycle and Hormone Control: Understand the key hormones involved in the menstrual cycle including FSH, LH, oestrogen and progesterone, and learn how they work together to control egg maturation, ovulation and maintaining the uterus lining.
• Introduction to the Endocrine System: Learn about the principles of hormonal coordination and how the endocrine system works, including the role of glands, hormones, and target organs. Discover why the pituitary gland is called the 'master gland' and how hormonal control compares to nervous system control.

Plant hormones (biology only)

• Plant Hormones in Agriculture and Horticulture: Explore how auxins and gibberellins are used commercially in farming and gardening, including weed control, rooting powders, tissue culture, and promoting plant growth and flowering.
• Plant Hormones in Food Production: Learn how ethene controls fruit ripening during storage and transport, and how plant hormones are used to increase fruit size in commercial food production.
• Plant Hormones and Growth Responses: Explore how plants use hormones like auxin to coordinate growth and respond to environmental stimuli such as light and gravity, understanding phototropism and gravitropism through unequal hormone distribution.
• Gibberellins and Ethene in Plant Development: Investigate the roles of gibberellins in seed germination and ethene in controlling cell division and fruit ripening, understanding how these hormones regulate key plant developmental processes.

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More in this course

Go back to the full GCSE AQA Higher Biology topic list, or practise this topic with past-paper questions.