bioenergetics

Question 1

Plant cells contain chloroplasts which contain _________. Chlorophyll is a _______ that can absorb light energy.

Answer 1

Plant cells contain chloroplasts which contain chlorophyll. Chlorophyll is a pigment that can absorb light energy.

Question 2

endothermic reactions require _______

Answer 2

energy

Question 3

Photosynthesis takes place inside chloroplasts found in plants and algae. The reaction is __________, meaning that it requires energy. The source of this energy is sunlight, which is ________ by a chemical called chlorophyll inside chloroplasts in plant cells.

Answer 3

Photosynthesis takes place inside chloroplasts found in plants and algae. The reaction is endothermic, meaning that it requires energy. The source of this energy is sunlight, which is trapped by a chemical called chlorophyll inside chloroplasts in plant cells.

Question 4

Factors affecting the rate of photosynthesis:

Answer 4

CO2 and chlorophyll concentration

light intensity

temp

Question 5

Factors affecting the rate of photosynthesis: temperature

Answer 5

Increasing the temperature increases the rate of photosynthesis because more energy is provided.

However, if the temperature is increased to above about 45°C, the enzymes that catalyse (speed-up) the reaction begin to denature (not work anymore).

This causes the rate of the reaction to drop sharply until it stops altogether.

Question 6

Factors affecting the rate of photosynthesis: carbon dioxide concentration

Answer 6

Carbon dioxide concentration

Increasing the carbon dioxide concentration increases the rate of photosynthesis because carbon dioxide is a reactant in photosynthesis.

However, above a certain threshold, further increases in the carbon dioxide concentration do not increase the rate of photosynthesis because another factor (such as light intensity) is limiting the rate of reaction.

Question 7

Factors affecting the rate of photosynthesis: Light intensity

Answer 7

Increasing light intensity increases the rate of photosynthesis because more energy is provided.

However, if the light intensity is increased above a certain threshold, the rate of photosynthesis will not increase because another factor (such as temperature) is limiting the rate of the reaction.

Question 8

Balance the following photosynthesis question:

_CO2 + _H2O –> C6H12O6 + _O2

Answer 8

Balance the following photosynthesis question:

6CO2 + 6H2O –> C6H12O6 + 6O2

Question 9

In plants, glucose from photosynthesis can be converted into:

Answer 9

In plants, glucose from photosynthesis can be converted into:

Starch

Cellulose

Fats

Proteins

Question 10

CO2 concentration, light levels and temperature are all at optimum values. What might be the limiting factor of rate of photosynthesis, and why?

Answer 10

CO2 concentration, light levels and temperature are all at optimum values. What might be the limiting factor of rate of photosynthesis, and why?

The concentration of mineral ions in the soil is probably the limiting factor.

Chlorophyll absorbs light energy and the production of chlorophyll requires these mineral ions (especially Mg2+).

Question 11

Identify the products of glucose in plants: Starch

Answer 11

Identify the products of glucose in plants:

Starch
Insoluble, stored in stems, leaves or roots.

Question 12

Identify the products of glucose in plants:

Proteins

Answer 12

Identify the products of glucose in plants:

Proteins
Required for cell growth, repair, and enzymes.

A source of nitrogen is also needed for glucose to be converted into proteins.

Plants get this nitrogen by absorbing nitrate ions (minerals) from soil.

Question 13

Identify the products of glucose in plants:

Fats

Answer 13

Identify the products of glucose in plants:

Fats
Stored in structures such as seeds. For example, sunflower seeds are a key ingredient in cooking oils.

Question 14

Identify the products of glucose in plants:

Cellulose

Answer 14

Identify the products of glucose in plants:

Cellulose
Particularly important for fast-growing plants, is used to strengthen cell walls.

Question 15

To investigate the effect of light intensity on the rate of photosynthesis I would:

Answer 15

use an aquatic plant(lives under water) like pondweed

count number of bubbles plant produces

change the distance between lamp and pondweed

Question 16

What is the light intensity when a lamp is placed 5cm away from a plant?

Answer 16

What is the light intensity when a lamp is placed 5cm away from a plant?

1
Remember the equation for light intensity
Light intensity (L) = 1 ÷ distance2
2
Substitute in the values
L = 1 ÷ 52
3
Work out the squared value
L = 1 ÷ 25
4
Write the answer
L = 1/25

Question 17

equation for light intensity

Answer 17

equation for light intensity
Light intensity (L) = 1 ÷ distance2

Question 18

In an experiment using pondweed to investigate the effect of light intensity on the rate of photosynthesis, the light intensity is the __________ variable and the number of bubbles is the ________ variable.

Answer 18

In an experiment using pondweed to investigate the effect of light intensity on the rate of photosynthesis, the light intensity is the independent variable and the number of bubbles is the dependent variable.

Question 19

A variable is …

Answer 19

A variable is something you are trying to measure

Question 20

a dependent variable is ….

Answer 20

a dependent variable is exactly what it sounds like. It is something that depends on other factors.

Question 21

An independent variable is ….

Answer 21

An independent variable is exactly what it sounds like. It is a variable that stands alone and isn’t changed by the other variables you are trying to measure.

For example, someone’s age might be an independent variable.

Question 22

Organisms need to make __________ from ___________. Proteins can be made from __________. These are built from sugars and other nutrients in plants.

Answer 22

Organisms need energy to make large molecules from smaller molecules. Proteins can be made from amino acids. These are built from sugars and other nutrients in plants.

Question 23

what molecules can be joined together to produce starch?

Answer 23

glucose

Question 24

Organisms needs energy for:

Answer 24

homeostasis

muscle contraction

growth

Question 25

Respiration is an _________ reaction that supplies all the energy needed by living organisms.

This reaction, which happens continually in all living cells, can be aerobic (with oxygen) or anaerobic (without oxygen).

Answer 25

Respiration is an exothermic reaction that supplies all the energy needed by living organisms.

This reaction, which happens continually in all living cells, can be aerobic (with oxygen) or anaerobic (without oxygen).

Question 26

glucose can be combined with _________ to make amino acids

Answer 26

glucose can be combined with nitrate ions to make amino acids

Question 27

When there is not enough oxygen, what is glucose converted to in animal cells?

Answer 27

lactic acid

Question 28

Metabolic reactions include breaking down excess _______ to form urea, which is excreted.

Answer 28

Metabolic reactions include breaking down excess proteins to form urea, which is excreted.

Question 29

Types of respiration:

Answer 29

Types of respiration:

1
Anaerobic
2
Aerobic

Question 30

metabolic reactions is helped by _______

Answer 30

metabolic reactions is helped by enzymes

Question 31

metabolic reactions create ___________________

Answer 31

new molecules

Question 32

metabolic reactions is the sum of _______________

Answer 32

metabolic reactions is the sum of all chemical reactions

Question 33

Fermentation

Answer 33

Fermentation

glucose→ethanol+carbon dioxide

Question 34

How does the body respond to increased energy demands during exercise? (4)

Answer 34

breath volume increases

heart and breathing rate increases

blood vessels dilate

Question 35

What is the toxic byproduct of anaerobic respiration?

Answer 35

lactic acid

Question 36

Exercise increases the body’s energy demands. The rate of ________ must increase in order to meet these new requirements.

Answer 36

Exercise increases the body’s energy demands. The rate of respiration must increase in order to meet these new requirements.

Question 37

breathing rate and breath volume increases …

Answer 37

breathing rate increases gas exchange in the lungs, with more oxygen taken in and more carbon dioxide released.

Question 38

Blood vessels dilate (open wider) to ensure …

Answer 38

Blood vessels dilate (open wider) to ensure more blood reaches the muscles.

Question 39

An increase in heart rate delivers …

Answer 39

An increase in heart rate delivers more blood (containing glucose and oxygen) to the muscles.

Question 40

Oxygen debt refers to the extra oxygen needed after exercise to ___________ and remove it from cells.

Answer 40

Oxygen debt refers to the extra oxygen needed after exercise to oxidise lactic acid and remove it from cells.

Question 41

If muscles are not supplied with enough oxygen during long periods of activity, …..

Answer 41

If muscles are not supplied with enough oxygen during long periods of activity, then muscle cells may begin to respire anaerobically.