Science 2nd Form 2026

ecosystem processes

what is a producer?

Producers are organisms that make their own food eg plants or algae

What are consumers?

Consumers are organisms that have to eat other organisms to survive eg animals

How do plants make their own food?

By photosynthesis. A chemical reaction in which plants take in carbon dioxide and water and change it into glucose and oxygen using light energy from the sun.

what is the word equation of photosynthesis

Carbon dioxide and water (using light energy) > oxygen and glucose

What happens to the oxygen?

Oxygen is a waste product and is released back into the atmosphere

Where does photosythesis take place?

In chloroplasts in the leaf cells. Green pigment called Cholophyll absorbs the sunlight energy needed to transfer the water and carbon dioxide needed to make glucose.

How does water get into a plant?

Water diffuses from soil into the root hair cells. It is then transported around the plant through xylem tubes. As water is evaporated from leaves, more water is drawn up like sucking from a straw.

HOw do the gases get into the leaves?

On the underside of the leaf are tiny holes that allow the gases to diffuse into the leaf.

Why would photosynthesis not take place at night

No sunlight energy for photosynthesis to take place

What 4 ways have a leaf adapted for photosynthesis?

1. They are green - contain chlorophyll needed to absorb sunlight. Upper side is greener than underside.

2. THey are thin - allow the gases to diffuse through quickly.

3. THey have a large surface area to absorb as much light as possible

4. Have veins - contain xylem tubes to transport water to leaves and glucose once made to parts of the plant as food

Why are leaves waxy on the top of leaf?

To prevent so much water evaporating out of the leaf as it needs the water for photosynthesis

What are stomata

These are tiny holes on bottom of the leaf which allow gases to diffuse in and out of leaf

what are the reactants and products of photosynthesis

Carbon dioxide and water are reactants and oxygen and glucose are products

What is the palisade layer of a leaf

It is under the waxy layer - it is full of chloroplasts (and chlorophyll)

What are the 2 layers of a leaf and what is their function?

1. palisade layer - contains chloroplasts - gets most of sunlight as near the top

2. spongy layer - underneath palisade layer - nearer the bottom and just above the stoma and guard cells, contains air spaces to allow the gases to diffuse easily through the leaf to the chloroplasts or allow the oxygen to easily diffuse out of the leaf.

What 4 minerals do plants need and why?

1. Nitrates for healthy growth. They produce amino acids which make proteins,needed for cell growth.

2. Phosphates for healthy roots

3. Potassium for healthy leaves and flowers

4. Magnesium for making chlorophyll - leaves look yellow without these

Where do they get these minerals

Plants absorb the minerals from the soil through the root cells

what is a mineral deficieny?

When a plant doesn’t have enough minerals, its growth will be poor.

Why do farmers add fertilisers?

When crops are harvested, the minerals are removed from the soil. They would normally be replaced by plants when they die. This means farmers have to add more minerals for their crops into the soil.

What is the word equation for aerobic respiration?

Oxygen + glucose > energy, carbon dioxide and water

What is aerobic respiration?

it is the reaction with glucose and oxygen to make energy which is needed for cell growth. Waste products are carbon dioxide and water

Where does respiration take place?

It happens in the mitochondria in your cells

How does glucose get into your cells

it is a carbohydrate taken in as food, broken down into smaller molecules and absorbed into the bloodstream from the intestine. It dissolves in the liquid part of blood (called plasma) and can be diffused into cells that need it for respiration

How does oxygen get into your body?

It is breathed into lungs, then diffuses into your bloodstream. Is carried in the red blood cells (in the haemoglobin) and carried around to cells requiring oxygen.

What is anaerobic respiration

This is when the body needs energy fast and doesn’t have enough oxygen. Glucose > lactic acid + energy

Why does the body use aerobic respiration most of the time

1. Aerobic respiration produces a lot more energy per glucose than anaerobic respiration

2. Lactic acid produced can cause painful cramps in your stomach

What is fermentation?

is a type of anaerobic respiration. It produces ethanol and carbon dioxide + energy from glucose without oxygen

Where might you see fermentation

Yeast is used to produce bread, beer and wine using fermentation

What is a food chain

A diagram showing the transfer of energy between organisms

What is a food web

A diagram showing linked food chains

What is a carnivore

an animal that eats other animals

what is a herbivore

An animal that eats only plants

What is an omnivore

An animal that eats both plants and other animals

What is a prey organism

An organism that is eaten by another animal

What is a predator

It eats other animals

How much energy is passed on from one level of the chain to the next

About 10%

Why do food chains only have 4 or 5 links

If more, too little energy would be passed on