P1

Question 1

What are the parts in a plant cell?

Answer 1

Nucleus
Cytoplasm
Mitochondria
Cell wall
Ribosomes

Question 2

What is the formula for magnification?

Answer 2

magnification = size of image ÷ real size image

Question 3

What are the two functions of the digestive system?

Answer 3

1. Breaks down complex food substances

2. Provides the very large surface area for maximum absorption of food

Question 4

What are the functions of:

1. Carbohydrates
2. Proteins
3. Lipids

Answer 4

1. Source of energy, glucose is the main respiratory substrate
2. Growth and repair
3. Energy, make up part of cell membranes so essential for normal growth

Question 5

Carbohydrates in our diet include sugars and starches.

Answer 5

The glucose molecule is small enough to be absorbed directly through the walls of the digestive system.

Starch is a polymer of glucose. It must be broken down into glucose molecules – it is too large to pass through the gut.

Question 6

Cellulose up of glucose molecules.

Answer 6

It makes up plant cell walls. It is therefore a fundamental part of our diet. It cannot be broken down by the digestive system, so is egested from the gut.

Question 7

In plant metabolism, the glucose produced by photosynthesis is converted into starch for storage, and cellulose, for cell wall synthesis.

Answer 7

In humans and animals glucose is stored in glycogen. It is not converted into starch.

Question 8

Proteins

Proteins are made up of amino acids.

Answer 8

Proteins are big molecules that are too large to pass through the gut wall. They must first be broken down into amino acids.
inside the body, the amino acids are reassembled into the proteins the individual requires – the process of protein synthesis.

Excess amino acids are broken down in the liver.

Question 9

Lipids

Lipids are esters of fatty acids and glycerol.

Answer 9

Lipid molecules are too large to pass through the gut wall and must be digested first.

In the body’s cells, they are reassembled into the lipids the cell needs, for instance, for the cell membranes.