Respiration and carbohydrates

Question 1

Respiration definition

Answer 1

Cells break down food molecules and release the energy they contain

Question 2

Glycolysis

Answer 2

Occurs in cytoplasm where glucose is broken down into pyruvate

Question 3

Pyruvate fermentation

Answer 3

Under anaerobic conditions pyruvate is fermented and NADH is recycled

Question 4

What is the mitochondrial matrix?

Answer 4

• Pyruvate enters under aerobic conditions
• Pyruvate is decarboxylated to produce acetyl CoA for TCA cycle

Question 5

What is the TCA cycle?

Answer 5

The second stage of cellular respiration

Question 6

What is produced in the TCA cycle?

Answer 6

• 3 NADH
• 1 FADH2
• 1 ATP
• Release of 2 CO2 molecules

Question 7

The electron transport chain

Answer 7

• Located in the inner mitochondrial membrane
• NADH and FADH2 are oxidised back to HAD and FAD
• Electrons from NADH pass down a series of electron carriers and are donated to oxygen
• Protons are pumped out of the mitochondria to produce ATP

Question 8

How many protons are needed for ATP production?

Answer 8

4

Question 9

How is the TCA cycle controlled?

Answer 9

• Pyruvate dehydrogenase is inhibited by ATP, acetyl CoA and NADH
• Isocitrate dehydrogenase is inhibited by NADH and ATP but activated by ADP
• Ketoglutarate dehydrogenase is inhibited by NADH, ATP and succinyl CoA

Question 10

How is glycolysis controlled?

Answer 10

Feedback regulation allows cells to switch from glucose breakdown to synthesis

Question 11

What is glycogenesis?

Answer 11

Generation of glucose from non-carbohydrate sources

Question 12

Function of glucogenesis

Answer 12

Maintain blood glucose levels in liver and kidney

Question 13

Lactase

Answer 13

Made from glucose and galactose

Question 14

Maltose

Answer 14

Made from 2 glucose molecules

Question 15

Trehalose

Answer 15

Made from 2 units of glucose but with a different glycosidic bond

Question 16

Uses of polysaccharides

Answer 16

Storage or structure

Question 17

What is cellulose?

Answer 17

Polymer of glucose which provides structure in cell walls

Question 18

How are cellulose fibres made?

Answer 18

Glucose polymers cross link into cellulose microfibrils which align into cellulose macrofibrils and hence cellulose fibres

Question 19

What are cell walls made from?

Answer 19

Cellulose cross linked by hemicellulose, pectin and proteins

Question 20

How is cellulose made into the cell wall?

Answer 20

Cellulose synthase enzyme complex

Question 21

What do cellulase enzymes do?

Answer 21

Break down cellulose into glucose

Question 22

What carbohydrates are used in plants and animals?

Answer 22

Starch and glycogen

Question 23

What is inulin?

Answer 23

Polymer of fructose

Question 24

What is glycogen?

Answer 24

Polymer of glucose joined by 1-4 linkages and 1-6 linkages

Question 25

What is glycogenin?

Answer 25

A protein at the centre of glycogen which initiates glycogen biosynthesis and adds glucose molecules

Question 26

Where is glycogen found in humans?

Answer 26

Skeletal muscles and liver

Question 27

Why is glycogen important?

Answer 27

Can be degraded by phosphorylase to maintain sugar levels

Question 28

Digestion of cellulose

Answer 28

Cows and termites are effective at digestion as they have long digestion times but human digestion is poor

Question 29

What is chitin?

Answer 29

Polymer of glucose with 1 acetyl amine group

Question 30

What is chitosan?

Answer 30

Chitin waste treated with alkali for positive use