Chapters 9-10: Bioenergetics

Question 1

What is photosynthesis?

Answer 1

A chemical reaction that takes place in cell chloroplasts and converts water and carbon dioxide into oxygen and glucose using energy from the sun

Question 2

What is the balanced symbol equation for photosynthesis?

Answer 2

6CO2 + 6H2O => C6H12O6 + 6O2

Question 3

Where does the majority of photosynthesis take place?

Answer 3

Palisade mesophyll leaf cells as they face the sun and have many chloroplasts

Question 4

How do gases enter leaves?

Answer 4

They are absorbed from the air into the spaces between the spongy mesophyll cells

Question 5

How does water enter leaves?

Answer 5

It osmoses into the root hair cells and is transported to the rest of the plant through xylem vessels in transpiration

Question 6

How is glucose distributed throughout a plant?

Answer 6

It is produced in the leaves and then transported in phloem tissue to other parts of the plant (translocation)

Question 7

What other organisms photosynthesise?

Answer 7

Algae (uni- and multicellular eukaryotic organisms). Some algae have other photosynthetic pigments that are red or brown

Question 8

What is a limiting factor?

Answer 8

Anything that reduces or stops the rate of a reaction

Question 9

What are the 4 limiting factors in photosynthesis?

Answer 9

Low temperatures, CO2 shortage, shortage of light, shortage of chlorophyll

Question 10

Why do lower temperatures reduce rates of photosynthesis?

Answer 10

The particles have less kinetic energy, so they collide less and react less

Question 11

What is chlorosis?

Answer 11

When a plant has a magnesium deficiency and can’t produce enough chlorophyll, giving it a yellow appearance

Question 12

How do plants take in minerals from the soil?

Answer 12

Through active transport (concentrations are lower in the soil than in the plant)

Question 13

What is yield?

Answer 13

The amount of an agricultural product. Yield can be maximised by growing plants at optimal conditions. When one factor stops being the limiting factor, another factor becomes the limiting factor

Question 14

What is do plants use their glucose for?

Answer 14

1. Producing cellulose for structural growth and making cell walls
2. Respiration to release energy for chemical reactions
3. They convert it to starch and store it
4. making proteins and amino acids for growth
5. Converted into fats and oils and stored

Question 15

How much energy is wasted when one algorithm consumes another?

Answer 15

90%

Question 16

How would you investigate the effect of light intensity on the rate of photosynthesis using an aquatic organism?

Answer 16

1. Cut a piece of pond weed, attach a paperclip to.it to weigh it down and place it into a boiling tube filled with water
2. Set up a lamp 50cm from the boiling tube and place a tank of water between them
3. Turn off the lights and turn the lamp on for 2 minutes
4. Place a thermometer in the boiling tube to ensure the temperature remains constant
5. Count the number of bubbles produced in 1 minute, then repeat this 2 more times to get a mean
6. Repeat steps 2-6 with 40cm, 30cm, 20cm and 10cm

Question 17

What is respiration?

Answer 17

An exothermic reaction that takes place in the mitochondria in which glucose and oxygen react to release energy, carbon dioxide and water (which comes out in our breath)

Question 18

What is the balanced symbol equation for respiration?

Answer 18

C6H12O6 + 6CO2 => 6CO2 + 6H2O (this is the inverse of photosynthesis in plants)

Question 19

What is this energy converted to?

Answer 19

Thermal energy for keeping the animal warm, a chemical store of energy for reactions and movement

Question 20

What is anaerobic respiration?

Answer 20

When not enough oxygen is being provided to the cells for aerobic respiration, glucose will be converted into lactic acid, releasing 5% of the energy released in aerobic respiration

Question 21

What causes muscle cramp?

Answer 21

A buildup of lactic acid preventing the muscle from contracting efficiently

Question 22

What is oxygen debt?

Answer 22

After a human stops exercising, they will continue to breath heavily to convert the remaining lactic acid into oxygen (lactic acid + oxygen => carbon dioxide + water), releasing 95% of the energy

Question 23

Where does this process take place?

Answer 23

In the liver (the lactic acid diffuses from a high concentration in the muscles to a lower concentration in the blood. By the time the blood reaches the liver it has a high concentration and diffuses into the liver)

Question 24

What other organisms respire?

Answer 24

Plants and micro-organisms

Question 25

What is the equation for anaerobic respiration in micro-organisms such as yeast?

Answer 25

Glucose => Ethanol + carbon dioxide (known as fermentation)

Question 26

What is this reaction used for?

Answer 26

Making alcoholic drinks and bread (the yeast is killed by heat before it can make too much ethanol, which evaporates away)

Question 27

What is metabolism?

Answer 27

The sum of all the chemical reactions that take place in the body (they are catalysed by enzymes)

Question 28

What are breakdown reactions?

Answer 28

Reactions where larger molecules are broken down into smaller ones. These reactions do not require much energy

Question 29

What happens when proteins are broken down?

Answer 29

They are broken down into amino acids, which diffuse into the liver in the same way as lactic acid, where they are then broken down into urea, which is excreted by the kidneys

Question 30

What happens to amino acids?

Answer 30

An anime group is removed, creating urea

Question 31

What are synthesis reactions?

Answer 31

Reactions where smaller molecules are combined to make larger ones. These reactions require more energy

Question 32

What is glucose synthesised into?

Answer 32

Starch (for storage), cellulose (cell walls in plants), glycogen (for storage in the liver)

Question 33

How are lipids made?

Answer 33

They are made from 3 molecules of fatty acids and one molecule of glycerol

Question 34

What are lipids used for?

Answer 34

Chemical store of energy, making cell membranes

Question 35

How are proteins made?

Answer 35

Glucose and nitrate ions are used to make amino acids. A chain of amino acids are then folded into a specific shape to make a protein