Metabolism Flashcards – AQA GCSE Combined Science: Trilogy (8464) — Biology — Higher

What is metabolism?

The sum of all chemical reactions in a cell or organism.

How often do metabolic reactions occur?

Continually.

What controls metabolic reactions?

Enzymes.

What two broad types of reactions are included in metabolism?

Reactions that break down molecules and reactions that synthesise new molecules from smaller substances.

What is the role of respiration in metabolism?

It transfers energy for other processes, including the synthesis of larger molecules.

How is glycogen, an animal storage carbohydrate, formed?

Glucose molecules are joined together.

What molecules are joined to form a triglyceride lipid?

One glycerol molecule and three fatty acid molecules.

How can plants use glucose to release energy for cellular processes?

They use it in respiration.

What two forms can plants convert glucose into for storage?

Insoluble starch and fats and oils.

What is the role of cellulose made from glucose in plants?

It strengthens plant cell walls.

How is glucose used to make proteins in plants?

Glucose is used to produce amino acids, which are joined together to make proteins.

How do plants obtain the nitrogen needed for amino acid and protein synthesis?

They absorb nitrate ions from the soil through their roots.

What are proteins broken down into?

Amino acids.

Why are excess amino acids broken down?

They cannot be stored as amino acids.

Where are excess amino acids broken down by deamination?

In the liver.

What happens during deamination of an amino acid?

Its nitrogen-containing amino group is removed, producing ammonia.

Why must ammonia produced by deamination be converted into another substance?

Ammonia is toxic.

What does the liver convert ammonia into?

Urea.

How does urea leave the body after it is formed in the liver?

It is transported in the blood to the kidneys and excreted in urine.