Humans as organisms

Balanced diet

Eating a wide variety of foods to get all substances the body needs.

Nutrients

Carbs, protein, fats, vitamins and minerals used to make materials the body needs.

Water

Needed because it dissolves substances and fills cells.

Fibre

Keeps the digestive system healthy.

Sugary carbohydrate

Provides quick‑release energy.

Sources of sugary carbohydrate

Sugary foods.

Starchy carbohydrate

Provides slow‑release energy.

Sources of starchy carbohydrate

Pasta and bread.

Protein

Needed for growth and repair.

Sources of protein

Meat, fish, nuts.

Fats

Store energy and insulate the body.

Sources of fats

Milk, cream, butter.

Vitamins

Needed for health.

Sources of vitamins

Fruit and vegetables.

Minerals

Needed for health.

Sources of minerals

Fruit, vegetables, dairy products.

Food test for protein

Add biuret solution → turns blue to purple.

Food test for glucose

Add Benedict’s solution and heat → turns blue to green/yellow/red.

Food test for starch

Add iodine → turns brown to blue‑black.

Food test for fat

Rub food on filter paper → greasy mark appears.

Digestion

Breaking large food molecules into small ones the body can absorb.

Mechanical digestion

Physical breakdown of food (e.g. chewing).

Chemical digestion

Breakdown of food using enzymes.

Enzymes

Chemicals that speed up reactions and break down food.

Enzyme reuse

Enzymes are not used up and can be reused.

Villi

Finger‑like projections that increase surface area for absorption.

Villi blood supply

Lots of blood vessels to absorb nutrients quickly.

Pathogen

A microbe that causes disease.

Types of pathogen

Bacteria, fungi, viruses.

Bacteria

Single‑celled, no nucleus, divide to reproduce, need warmth/moisture, cause food poisoning.

Fungi

Single or multicellular, include moulds/yeast, made of hyphae, decompose tissue, spread by spores.

Viruses

Smallest microbes, not cells, invade host cells and destroy them, cause influenza.

Lifestyle disease

Caused by behaviour (e.g. too much sugar → diabetes).

Genetic disease

Caused by DNA abnormalities (e.g. Down’s syndrome).

Transmission by touch

Spread by contact with infected people or surfaces.

Transmission by air

Spread by droplets (e.g. sneezing).

Transmission by water/food

Spread by contaminated food or drink.

Transmission by animals

Spread by vectors (e.g. mosquitoes → malaria).

First line of defence

Skin, scabs, mucus, hairs, tears stop microbes entering.

Tears

Contain enzymes that kill bacteria.

Second line of defence

Phagocytes engulf and digest pathogens.

Phagocyte

Non‑specific white blood cell that engulfs anything foreign.

Third line of defence

Lymphocytes produce antibodies.

Antibodies

Y‑shaped substances that stick to pathogens.

Antibody job 1

Make pathogens stick together.

Antibody job 2

Mark pathogens for destruction by phagocytes.

Antibody specificity

Each pathogen needs a different antibody.

Skeleton function 1

Supports the body.

Skeleton function 2

Protects vital organs.

Skeleton function 3

Allows movement with muscles.

Skeleton function 4

Bone marrow makes blood cells.

Joint

Where two bones meet.

Tendon

Attaches muscle to bone.

Antagonistic muscles

Muscle pairs that work together to move a joint.

Bicep and tricep

Example of antagonistic pair at the elbow.

Ligament

Holds bones together.

Cartilage

Protects bone ends and stops rubbing.

Arthritis

Cartilage wears away causing pain, stiffness and swelling.

Synovial fluid

Lubricates the joint.

Synovial capsule

Produces and holds synovial fluid.

Evolution

Gradual change in species over millions of years.

Common ancestor

Species from which humans and chimpanzees both evolved.

Hominid

Human‑like species shown in fossils.

Quadruped

Walks on four legs.

Biped

Walks on two legs.

Advantage of biped 1

See over obstacles.

Advantage of biped 2

Uses less energy.

Advantage of biped 3

Reach higher food.

Advantage of biped 4

Wade through deep water.

Advantage of biped 5

Hands free for other uses.

Advantage of biped 6

Increased agility and speed in some cases.

Human brain evolution

Humans evolved larger brains for tool use and social behaviour.