B1- Key Concepts in Biology

Question 1

1. Explain the role of the active site of an enzyme (2)

Answer 1

The active site has a specific shape (1); where the substrate binds (1)

Question 2

2. Explain how electron microscope have helped our understanding of cells (2)

Answer 2

They have a higher magnification and resolution (1) more sub-cellular structures are visible (1)

Question 3

3. Explain why enzymes can only catalyse specific reactions (2)

Answer 3

The active site of the enzyme has a specific shape because of the order of amino acids (1) that made the enzyme. The substrate must have a shape that is complementary. (1)

Question 4

4. Explain how to use a light microscope to view a slide (3)

Answer 4

Place slide on stage of the microscope and look through the eyepiece lens (1) and turn the focussing wheel (1) to see the image.

Question 5

5. State how the DNA in a bacterial cell is organised (2)

Answer 5

One large loop of chromosomal DNA (1) and smaller loops called plasmids (1)

Question 6

6. Why does the rate of enzyme catalysed reactions drop above 37° celsius? (2)

Answer 6

The active site changes shape (1) and the enzyme becomes denatured (1)

Question 7

7. Which monomers make up proteins? (1)

Answer 7

Amino acids (1)

Question 8

8. Describe the function of the mitochondria (2)

Answer 8

Where aerobic respiration (1) occurs which releases energy (1)

Question 9

9. Define osmosis (3)

Answer 9

Movement of water molecules (1) from an area of high concentration to an area of low concentration (1) through a partially permeable membrane (1)

Question 10

10. When is active transport used? (2)

Answer 10

When molecules need to be transported against a concentration gradient (1) or are too big to diffuse (1) through a cell membrane