KS3 Science (Biology) - Photosynthesis & the Carbon Cycle

Flashcards covering definitions and concepts related to photosynthesis, the carbon cycle, and climate change, based on lecture notes.

What is the process of photosynthesis?

A chemical reaction where plants use carbon dioxide and water to make their own food (glucose) and oxygen.

What are the two raw materials that plants need to make food?

Carbon dioxide (from the air) and water (from the soil).

What type of sugar is produced during photosynthesis?

Glucose.

Where do plants get the energy needed for photosynthesis?

Light energy from the Sun.

Which part of the plant cell absorbs light energy from the sun?

Chloroplasts, which contain the green pigment chlorophyll.

What is the word equation for photosynthesis?

Carbon dioxide + water + light energy -> glucose + oxygen.

How are leaves adapted for photosynthesis?

Leaves are thin, allowing gases to diffuse in and out quickly. Water is transported from the roots in xylem vessels.

How can you test if a plant has been photosynthesizing?

Test the leaf for the presence of starch.

What happens to the glucose produced during photosynthesis?

It is transported to the growing parts of the plant, transformed into cellulose, proteins and oils or turns into starch for storage.

How do plants get the minerals they need from the soil?

Roots take in minerals by active transport, requiring energy.

What are the three types of variables to consider when designing an experiment?

Independent, dependent, and controlled variables.

How does carbon move through the carbon cycle?

Plants take in carbon dioxide from the air via photosynthesis to make carbohydrates, fats, and proteins. Carbon is passed along the food chain as animals eat. Respiration and combustion return carbon dioxide to the atmosphere.

What are the equations for photosynthesis and cellular respiration?

Photosynthesis converts carbon dioxide and water into oxygen and glucose. Cellular respiration converts oxygen and glucose into water and carbon dioxide.

How does combustion affect the carbon cycle and carbon dioxide levels?

Burning fossil fuels releases stored carbon dioxide into the atmosphere.

What is the greenhouse effect?

Gases in the atmosphere trap escaping thermal energy, keeping the planet warm.

Name two important greenhouse gases.

Carbon dioxide and methane.

How do human activities cause carbon dioxide levels to increase?

Increased use of fossil fuels releases more carbon dioxide.

Name factors that have caused climate change in the past.

Ice ages and asteroid collisions

What are some of the impacts of climate change?

More extreme weather events, less predictable rainfall, and rising sea level.