Respiration and photosynthesis in organisms

Question 1

Plants are

Answer 1

autotrophs

Question 2

Autotrophs definition

Answer 2

This means they can make their own food using light, water and carbon dioxide

Question 3

Photosynthesis is an

Answer 3

endothermic reaction

Question 4

What happens during photosynthesis?

Answer 4

Energy is transferred from the environment to the chloroplasts by light

Question 5

Where does the most photosynthesis happen?

Answer 5

In the leaves of the plant, in specialised mesophyll cells which are packed with chloroplasts containing chlorophyll to absorb as much light energy as possible.

Question 6

How are the reactants for photosynthesis obtained by a plant?

Answer 6

• carbon dioxide: diffuses into the leaf through the stomata

- water: taken up by the roots and transported through the xylem to the leaves.

Question 7

products of photosynthesis

Answer 7

Glucose- it is used to make substances needed by the plant. It is used in respiration to release energy.
oxygen- diffuses out of the leaf through the stomata. It is used in respiration.

Question 8

What does a plant need in order to photosynthesise?

Answer 8

light, water and carbon dioxide

Question 9

The availability of light and carbon dioxide

Answer 9

can affect how much and how quickly (the rate) photosynthesis occurs

Question 10

Why is water not considered a limiting factor?

Answer 10

-the amount needed is relatively small compared to the amount of water transpired from a plant so there is hardly ever a situation where there is not enough water for photosynthesis

Question 11

What can affect the rate of photosynthesis?

Answer 11

• temperature
• the amount of chlorophyll in the chloroplasts
• light
• carbon dioxide

Question 12

Temperature

Answer 12

-The temperature of the environment affects how much kinetic energy all particles have – so temperature affects the speed at which carbon dioxide and water move through a plant
-The lower the temperature, the less kinetic energy particles have, resulting in fewer successful collisions occurring over a period of time
I-ncreasing temperature increases the kinetic energy of particles, increasing the likelihood of collisions between reactants and enzymes which results in the formation of products
-At higher temperatures, however, enzymes that control the processes of photosynthesis can be denatured (where the active site changes shape and is no longer complementary to its substrate) – this reduces the overall rate

Question 13

Light

Answer 13

• The intensity of the light available to the plant will depend on the amount of energy that it has to carry out photosynthesis
• The more light a plant receives, the faster the rate of photosynthesis
• This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply

Question 14

Carbon dioxide concentration

Answer 14

• Carbon dioxide is one of the raw materials required for photosynthesis
• This means the more carbon dioxide that is present, the faster the reaction can occur
• This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply

Question 15

Chlorophyll

Answer 15

• The number of chloroplasts (as they contain the pigment chlorophyll which absorbs light energy for photosynthesis) will affect the rate of photosynthesis
• The more chloroplasts a plant has, the faster the rate of photosynthesis
• The amount of chlorophyll can be affected by:
• diseases (such as tobacco mosaic virus)
• lack of nutrients (such as magnesium)
• loss of leaves (fewer leaves means fewer chloroplasts)

Question 16

light intensity

Answer 16

1/ distance

Question 17

Growing in a greenhouse

Answer 17

• Commercial horticulturists will grow their plants in a greenhouse
• This means that they are able to control as many of the limiting factors of photosynthesis as possible
• Limiting factors are important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit
• Keeping plants in a greenhouse has associated costs, but the increased yield of the crop and fact that the crop can be harvested more frequently, means that the farmer will make more money
• The levels of heat, light, water, carbon dioxide and nutrients are carefully controlled so only the smallest amounts needed are used so that farmers are not wasting money
• Eg. spending money on increasing the concentration of carbon dioxide beyond a point when some other factor limits the rate of photosynthesis is a waste

Question 18

Greenhouse adaptations

Answer 18

• ventilation helps prevent plants getting too hot
• shades removed from ceiling to allow maximum light
• artificial light for winter/darker hours
• heater burns paraffin and produces CO2
• watering system to make sure plants stay well watered
• Greenhouse traps the suns heat so that temperature doesn’t limit photosynthesis
• keeping plants in greenhouse makes it easier to keep from pests and diseases and add fertiliser

Question 19

How may the glucose produced in photosynthesis be used?

Answer 19

Used for respiration (both aerobic and anaerobic)- to release energy for cell
Converted into insoluble starch for storage in the stems, leaves and roots- won’t affect osmosis in cells
Used to produce fat or oil for storage (especially in seeds)
Used to produce cellulose, which strengthens the cell wall
Combined with nitrate ions absorbed from the soil to produce amino acids for protein synthesis
converted into sucrose for transport around the plant

Question 20

What is a test to show that a plant is photosynthesising?

Answer 20

-to test the leaf for the presence of starch using iodine (This can be used to show the effect of light on photosynthesis).

Question 21

Cellular respiration

Answer 21

• Cellular respiration is an exothermic reaction which is continuously occurring in living cells
• The chemical process of cellular respiration releases energy
• The energy transferred supplies all the energy needed for living processes to occur within cells and organisms as a whole

Question 22

What do organisms need energy for?

Answer 22

• Chemical reactions to build larger molecules from smaller molecules
• Muscle contraction to allow movement
• Keeping warm (to maintain a constant temperature suitable for enzyme activity)

Question 23

Uses of energy in the body of humans

Answer 23

• maintenance of a constant body temperature
• passage of nerve impulses
• muscle contraction
• protein synthesis
• active transport
• cell division and growth

Question 24

Aerobic respiration

Answer 24

• Respiration in cells can take place aerobically (using oxygen) to transfer energy; glucose is reacted with oxygen in this process
• Aerobic respiration uses oxygen and most of the reaction takes place in the mitochondria

Question 25

Anaerobic respiration in animals

Answer 25

• Respiration in cells can take place anaerobically (without oxygen), to transfer energy; it simply involves the incomplete breakdown of glucose into lactic acid
• This occurs when the body can’t supply enough oxygen for aerobic respiration, such as during vigorous exercise
• As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration
• Anaerobic respiration takes place without the need of oxygen

Question 26

Anaerobic respiration equation

Answer 26

Glucose –> lactic acid + (tiny amount) of energy

C6H12O6 –> 2C3H6O3 + 2ATP

Question 27

Anaerobic respiration in plants and yeast

Answer 27

• Plants and yeast can respire without oxygen as well, breaking down glucose in the absence of oxygen to produce ethanol and carbon dioxide
• Anaerobic respiration in yeast cells is called fermentation
• Fermentation is economically important in the manufacture of bread (where the production of carbon dioxide makes dough rise) and alcoholic drinks (as ethanol is a type of alcohol)

Question 28

anaerobic respiration in yeast equation/ fermentation

Answer 28

glucose –> alcohol + carbon dioxide

Question 29

cellular respiration definition

Answer 29

• It is a chemical process of transferring energy from glucose in all living cells.

Question 30

What happens when excercising?

Answer 30

• In order for an individual to be able to move, their muscles need to contract, which requires energy from respiration
• When exercising, the number of muscle contractions increases, therefore there is a greater energy demand, which means that the muscles need a greater supply of oxygen for aerobic respiration

Question 31

How does the human body react to the increased demand for oxygen when excercising?

Answer 31

• The breathing rate and breath volume increase during exercise to increase the amount of oxygen absorbed into the bloodstream by diffusion, and the amount of carbon dioxide removed
• The heart rate increases
• These reactions increase the supply of oxygenated blood to the muscles

Question 32

What happens during vigorous excercise?

Answer 32

• If exercising vigorously, the body may not be able to supply sufficient oxygen to the muscles to meet the demand for energy
• In this situation, some of the energy supplied to the muscles comes from anaerobic respiration, which is the incomplete breakdown of glucose without oxygen
• This releases much less energy than aerobic respiration and results in the formation of lactic acid as glucose is incompletely oxidised
• An “oxygen debt” is created after exercising in this way; it is a debt as “extra” oxygen is needed to react with the lactic acid produced via anaerobic respiration
• This is why an individual still breathes heavily at an increased rate (with a higher heart rate than usual) after exercising vigorously
• “Extra” carbon dioxide also has to be removed from the body
• During long periods of vigorous activity, muscles become fatigued and stop contracting efficiently as a result of increased levels of lactic acid building up

Question 33

Oxygen debt definition

Answer 33

It is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells

Question 34

How can the body deal with lactic acid?

Answer 34

• The body can deal with lactic acid in one of two ways
• It can be oxidised (reacted with oxygen) to form carbon dioxide and water – the same products formed in aerobic respiration
• Alternatively, blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose

Question 35

Metabolism

Answer 35

• Metabolism is the sum of all the reactions in a cell or the body – these reactions happen all of the time
• The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules
• Enzymes control all of the reactions occurring in cells; often the products of one reaction are the reactants for another (and so on)

Question 36

Metabolism involves

Answer 36

• Conversion of glucose to cellulose in plants to build and strengthen cell walls
• Conversion of glucose into glycogen in animals and starch in plants for storage
• The formation of lipid molecules from a molecule of -glycerol and three molecules of fatty acids to form triglycerides which are used for energy storage and as insulation in animals
• In plants: the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins required by cells (such as enzymes)
• Glucose is broken down in the process of respiration to release energy in all cells
• In animals, the breakdown of excess proteins to form urea for excretion

Question 37

hydrophonics

Answer 37

• uniform growth of a plant

- can grow the plant full of nutrients

Question 38

What are the 5 kingdoms?

Answer 38

Fungi, animals, protists, plants, prokaryotes

Question 39

What 3 kingdoms can do photosynthesis?

Answer 39

Protists, plants, prokaryotes

Question 40

Phloem transports

Answer 40

sucrose