Topic 1 - Key Concepts In Biology

Question 1

What is the role of the nucleus?

Answer 1

Contains genetic material that control the activities of the cell.

Question 2

What is the role of cytoplasm?

Answer 2

Gel-like substance that allows things to move around in the cell. Where most chemical reactions take place. Contains enzymes.

Question 3

What is the role of the cell membrane?

Answer 3

Holds the cell together and controls what enters or leaves the cell

Question 4

What is the role of the mitochondria?

Answer 4

Where respiration takes place

Question 5

What is the role of ribosomes?

Answer 5

Involved in the translation of gentic material in the synthesis of proteins

Question 6

What is the role of the cell wall?

Answer 6

Supports the cell and strengthens it

Question 7

What is the role of the vacuole?

Answer 7

Contains cell sap, a weak solution of sugar and salt. It maintains the internal pressure to support the cell.

Question 8

What is the role of the chloroplasts?

Answer 8

Where photosynthesis takes place

Question 9

State 3 differences between plant and animal cells

Answer 9

Cell wall
Vacuole
Chloroplasts

Question 10

State the equation for magnification

Answer 10

Magnification = image size / real size

Question 11

Reminder: you need to know how to prepare a specimen for a microscope

Answer 11

CGP Page 14

Question 12

What is the role of enzymes?

Answer 12

To speed up the ractions that take place in your body

Question 13

State the 3 factors that affects the rate of enzyme-catalysed reactions

Answer 13

Temperature
pH
Substrate Concentration

Question 14

What happens when an enzyme becomes denatured?

Answer 14

The active site of the enzyme changes shape, so it is no longer able to bind to the substrate.

Question 15

What causes an enzyme to denature?

Answer 15

Every enzyme has an optimum temperature and pH. When the environment the enzyme changes too much from the optimum environment, it damages the enzyme, causing the enzyme to denature.

Question 16

Why does temperature affect the rate of enzyme-catalysed reactions?

Answer 16

A higher temperature increases the rate at first because the enzymes have more energy. But if the temperature gets too high, some of the bongs holding the enzyme together break, causing the enzyme to denature.

Question 17

Why does pH affect the rate of enzyme-catalysed reactions?

Answer 17

Every enzyme has an optimum pH. If the pH is too high or low, it interferes with the bonds holding the enzyme together, causing it to denature.

Question 18

Which enzyme converts carbohydrates into simple sugars?

Answer 18

Carbohydrases

Question 19

Which enzyme converts protein into amino acids?

Answer 19

Proteases

Question 20

Which enzyme converts lipids into glycerol and fatty acids?

Answer 20

Lipases

Question 21

State the equation for calculating energy in food

Answer 21

Energy in food = Mass of water(g) x Temperature change of water x 4.2

Question 22

How do you find how much energy there is in food?

Answer 22

Burn the food under a boiling tube filled with water. Measure the temperature change and use the equation.

Question 23

What is diffusion?

Answer 23

The net movement of particles from an area of higher concentration to an area of lower concentration. Happens in liquid and gases.

Question 24

What is osmosis?

Answer 24

The net movement of water molecules across a partially permable membrane from a refion of higher water concentration to a region of lower concentration.

Question 25

What is active transport?

Answer 25

The movement of particles across a membrane against the concentration gradient using energy transferred during respiration.