Digestive System
This organ churns food and mixes it with acid and digestive enzymes.
Stomach
This muscular organ pumps blood around the body.
Heart
These two organs take oxygen into the body and remove carbon dioxide.
Lungs
These reproductive cells are called sperm in males and eggs in females.
Gametes
This body system provides support and protects organs such as the brain and heart.
Skeletal system
This tube carries food from the mouth to the stomach.
Oesophagus
These blood vessels carry blood away from the heart.
Arteries
This muscle beneath the lungs helps us breathe by changing the volume of the chest cavity.
Diaphragm
This organ produces sperm cells.
Testes
These organs filter the blood and produce urine.
Kidneys
Most digested nutrients are absorbed into the bloodstream in this organ.
Small intestine
These tiny blood vessels have very thin walls that allow substances to move between the blood and body cells.
Capillaries
Gas exchange occurs in millions of tiny air sacs called these.
Alveoli
Fertilisation occurs when these two types of cells join together.
Sperm and egg
This type of joint allows movement in many directions and is found at the shoulder and hip.
Ball-and-socket joint
Explain the difference between mechanical digestion and chemical digestion.
Mechanical digestion physically breaks food into smaller pieces; chemical digestion uses enzymes and other chemicals to break large molecules into smaller molecules.
Give two substances transported to body cells by the circulatory system and one substance transported away from cells.
Any two: oxygen, nutrients, water, hormones. Away: carbon dioxide or other wastes.
Explain how oxygen moves from the lungs into the bloodstream.
Oxygen diffuses from the alveoli, where its concentration is higher, across the thin alveolar and capillary walls into the blood.
What is the name of the first cell formed after fertilisation, and how is it formed?
A zygote. It forms when a sperm cell fuses with an egg cell during fertilisation.
Name three organs other than the kidneys that help remove wastes from the body and state one waste removed by each.
Examples: lungs—carbon dioxide; skin—water, salts and small amounts of urea in sweat; liver—processes harmful substances and forms urea.
Explain how the digestive and circulatory systems work together to supply body cells with nutrients.
Digestion breaks food into small nutrient molecules. These are absorbed through the small intestine into the blood. The circulatory system then transports the nutrients to cells throughout the body.
Explain why capillaries are better suited to exchanging substances with cells than arteries or veins.
Capillaries have walls only one cell thick and form extensive networks close to body cells, allowing rapid diffusion of substances between blood and tissues.
Explain how the respiratory and circulatory systems work together to supply cells with oxygen and remove carbon dioxide.
Oxygen enters the blood at the lungs and is transported to body cells. Carbon dioxide produced by cells enters the blood, travels back to the lungs and is exhaled.
Explain why gametes contain half the usual number of chromosomes and why this is important during fertilisation.
Gametes have half the normal chromosome number so that when sperm and egg join, the zygote receives the normal chromosome number rather than double.
Explain how the skeletal and muscular systems work together to produce movement at a joint.
Muscles are attached to bones by tendons. When muscles contract, they pull on bones. Bones move around joints, with opposing muscle pairs controlling movement in different directions.