Life Processes and Living Things

Key Facts Students Should Know

Cell structure:

• all living things are made up of cells
• the cell membrane controls the movement of substances into and out of the cell
• the nucleus stores genetic information and controls the cell
• the cytoplasm is a complicated solution in which many chemical reactions take place
• the cell wall is only found in plants and gives the plant its physical strength
• photosynthesis takes place in chloroplasts which are only found in plants

Moving the human body:

• muscles are attached to bones by tendons
• muscles contract to move bones
• muscles are arranged in antagonistic pairs to make repeated movements possible

Reproduction in humans:

• sperm are made in the testes of a man
• during ejaculation sperm pass out of a man's body through his penis
• an egg is released from one of a woman's two ovaries once every 28 days
• an egg can be fertilised when it meets a sperm in the oviduct
• once an egg has been fertilised it may grow into a baby
• if an egg is not fertilised it will pass out of the vagina together with blood and tissue from the lining of the uterus

Breathing:

• air passes into the lungs through the windpipe or trachea, bronchi and bronchioles
• alveoli are tiny sacs which provide a large surface area for diffusion
• smoking can cause alveoli to break down, resulting in emphysema
• smoking can cause cancer

Classifying animals:

• vertebrates are animals with backbones; invertebrates have no backbone
• mammals have furry skin and a constant body temperature; they give birth to live young which they feed with milk
• birds have feathers and a constant body temperature; they lay eggs with hard shells
• reptiles have dry scaly skin and usually live on land; they lay leathery eggs
• amphibians have moist skin and spend some of their time in water; they lay soft eggs in water
• fish have oily scales and live in water; they lay soft eggs

Feeding relationships:

• plants are called producers because they make their own food using photosynthesis
• animals are consumers because they obtain energy by eating plants or animals
• a food chain shows the flow of energy from organism to organism
• a pyramid of numbers shows the numbers of animals at each stage in a food chain
• interfering with food chains can have unpredictable effects