Biology B2: Body Systems, Genetics and Health

How the body works, and keeps going

This part of biology answers three big questions about the human body: how does it WORK, how are its features PASSED ON, and how does it stay HEALTHY. ⭐⭐ The body runs as coordinated ORGAN SYSTEMS. The digestive system breaks food down; the circulatory system transports blood; the breathing system exchanges gases; and the nervous and hormonal systems COORDINATE it all. Together they keep internal conditions steady, which is called HOMEOSTASIS. ⭐ Features are passed on through GENETICS. A GENE is a section of DNA, the molecule that carries the instructions for making an organism. Genes pass from parents to offspring, producing inherited VARIATION, while the environment causes further variation. ⭐⭐ The body must also stay HEALTHY. A PATHOGEN is a microorganism, such as a bacterium or a virus, that can cause disease. The IMMUNE system defends the body by recognising and destroying pathogens. This module is body systems, genetics and health. Cells, living processes and biodiversity are in the B1 module. ⚠️ Carry one question the whole way through: is this about how the body works, how features are inherited, or how the body stays healthy?

Three sides of the body

The three strands of this topic. Read across each one.

Tap the two body systems

Tap the TWO that are ORGAN SYSTEMS of the human body.

• The circulatory system, which transports blood around the body.
• The digestive system, which breaks food down into nutrients.
• A gene, a section of DNA carrying an instruction.
• A pathogen, a microorganism that can cause disease.

Naming the system at work

After a meal, food is broken down into small nutrients that pass into the blood. Which body system is mainly responsible for breaking the food down?

• The digestive system, because it breaks food down into nutrients the body can absorb
• The circulatory system, because blood is mentioned
• The nervous system, because it controls everything
• The immune system, because food carries germs

The words this topic uses

Six terms this topic turns on. Learn them and the body reads clearly.

Pair each system with its job

Two true things about the body

Select the TWO statements that are true.

• Homeostasis is keeping internal conditions, such as temperature, steady
• A gene is a section of DNA that carries an instruction
• A pathogen is a system that keeps the body healthy
• Every individual is genetically identical to their parents

Answering a body-and-health question

Strong answers name the right system or term and describe the mechanism, calmly and factually. ⭐⭐ NAME THE SYSTEM AND ITS JOB. Do not just say the body deals with food; say the digestive system breaks it down and the circulatory system transports the nutrients. The precise system and its job earn the mark. ⭐ KEEP GENETICS PRECISE. A gene is a section of DNA; DNA is the molecule that carries the instructions; variation comes from genes and the environment. Using the terms exactly shows understanding. ⭐⭐ DESCRIBE HEALTH AS A MECHANISM, NOT A JUDGEMENT. Explain that a pathogen causes disease and the immune system recognises and destroys it. Keep it factual: no blame, no graphic detail, and treat variation between people as normal. DO NOT DRIFT INTO B1 OR INTO EQUATIONS. Cells, biodiversity and the cell-level processes are in the B1 module; here, describe processes in words, not chemical equations, and keep to systems, genetics and health. ⚠️ A note on accuracy. Do not invent figures for how common a disease is or how fast something spreads; describe the direction and the mechanism. Keep the one question to hand: is this about how the body works, how features are inherited, or how the body stays healthy?

Order how a feature is inherited

Put the steps by which a characteristic passes from parents to a child into a sensible order.

• The parents carry genes for the characteristic
• Each gene is a section of the DNA in their cells
• Copies of genes pass into the sex cells
• A sperm and an egg join at fertilisation
• The offspring inherits a mix of the parents features

Build a point about the body

Assemble one sentence that describes homeostasis correctly.

The body-systems run

Five quick decisions about body systems, genetics and health. Three lives.

A ship and its crew

Leave biology aside for a moment. Picture a large ship on a long voyage, and how it keeps itself running, hands on its know-how, and protects itself. ⭐ First, it runs as a set of specialist teams. The engine crew drives it, the galley feeds everyone, the navigators steer, and the bridge coordinates them all so the ship holds a steady course and comfortable conditions, whatever the weather outside. No single sailor does everything; the teams together keep the whole ship on an even keel. ⭐⭐ Second, the ship carries a detailed logbook and manuals, the coded instructions for how everything is built and run. When a new crew takes over, a copy of that record is handed on, so the know-how passes to the next voyage rather than being lost. Third, the ship protects itself. Lookouts watch for trouble, and a trained guard can recognise and repel anyone trying to board and do harm, keeping the crew safe. ⚠️ Hold that picture. A living body works the same three ways: specialist systems keep conditions steady, coded instructions are copied and passed to the next generation, and defences recognise and repel invaders.

Finish each body line

Keeping internal conditions such as temperature steady is called _____. A section of DNA that carries the instruction for a characteristic is a _____. The molecule that stores the instructions for making and running an organism is _____. A microorganism, such as a bacterium or virus, that can cause disease is a _____. The body system that recognises and destroys pathogens is the _____ system.

Three body puzzles

Three situations are described. For each, choose the best scientific reading.

• On a hot day a person sweats and their skin flushes, and their body temperature stays about the same.
• Two children of the same parents look quite different from each other.
• A virus enters the body and the person later recovers and does not catch that illness again for a long time.

Explain the working body

Explain how the body works and stays going: name two organ systems and what each does, explain what homeostasis is, explain how a characteristic is inherited using the words gene and DNA, and explain how a pathogen and the immune system are related. Describe processes in words, not equations, and invent no figures.

• Name two organ systems and give each a job
• Explain what homeostasis is, with an example
• Explain how a characteristic passes from parent to offspring
• Use the words gene and DNA correctly
• Explain the relationship between a pathogen and the immune system