Topic 4- Bioenergetics Flashcards

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1
Q

What is photosynthesis?

A

Photosynthesis is the process by which plants make glucose from sunlight

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2
Q

Where does photosynthesis take place?

A

Within chloroplasts in leaf palisade cells. They contain chlorophyll, a pigment which absorbs light energy

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3
Q

State the word equation for photosynthesis

A

Carbon dioxide + water —(light)—> glucose + oxygen

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4
Q

State the symbol equation for photosynthesis

A

CO2 + H2O —> c6H12O6 + O2

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5
Q

Is photosynthesis an endothermic or exothermic reaction and why?

A

It is an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light

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6
Q

How can you show that a plant gives off oxygen during photosynthesis?

A

Using a water plant like Elodea

Collect gas bubbles produced during photosynthesis

The gas will relight a glowing splint as it contains oxygen

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7
Q

What do you have to do in order to carry out an experiment measuring the oxygen production of a plant?

A

Pond weed is placed in a test tube full with water

The top is sealed with a bung

A capillary tube also containing water leads into the tube and it is attached to a syringe

A lamp is placed at a measured distance from the tube

As it photosynthesises, oxygen is produced, forming a gas tube in the capillary tube

The distance the bubble has moved is measured using a ruler to calculate the volume of oxygen produced

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8
Q

How does temperature affect the rate of photosynthesis?

A

With an increase in temp, the rate of photosynthesis increases as the kinetic energy of particles is increased.

As the reaction is controlled by enzymes , this trend continues up to a certain temperature until the enzymes begin to denature and the rate of reaction decreases

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9
Q

How does light intensity affect the rate of photosynthesis?

A

For most plants, the higher the light intensity, the faster the rate of reaction

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10
Q

How does carbon dioxide concentration affect the rate of photosynthesis?

A

Carbon dioxide is also needed to make glucose

As the concentration of carbon dioxide increases, the rate of reaction increases

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11
Q

How does amount of chlorophyll affect the rate of photosynthesis?

A

Chlorophyll is a pigment in the leaf that converts light energy to food for the plant and is therefore essential

If, for example, chlorophyll levels are reduced through a magnesium deficiency, then the rate of photosynthesis would decrease

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12
Q

Give examples of leaf adaptations which maximise the rate of photosynthesis

A

Broad leaves - maximise surface area

Thin leaves - short diffusion distance

Guard cells- control opening of stomata for gaseous exchange and prevent water loss

Chlorophyll present - trap light energy

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13
Q

What is a limiting factor?

A

An environmental factor which can restrict the rate of photosynthesis e.g light intensity

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14
Q

How can farmers use their knowledge of limiting factors to increase their profits?

A

They can control temperature, light intensity and CO2 concentration to achieve the fastest possible rate of photosynthesis, leading to a greater yield

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15
Q

State 5 uses of the glucose produced during photosynthesis

A

Respiration

Starch for storage

Cellulose for strength

Amino acid and protein synthesis (combined with nitrates)

Lipids for energy storage in seeds

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16
Q

What is aerobic respiration?

A

An exothermic reaction which glucose reacts with oxygen to release energy which can be used by cells

17
Q

What are the equations for aerobic respiration?

A

Glucose + Oxygen —> carbon dioxide + water (+ energy)

C6H12O6 + 6O2 —-> 6CO2 + 6H2O

18
Q

Where does aerobic respiration take place?

A

In the mitochondria

19
Q

Why do organisms require the energy released by respiration?

A

Synthesis of larger molecules

Muscle contraction

Maintenance of body temperature

Active transport

20
Q

What is anaerobic respiration?

A

An exothermic reaction in which glucose is broken down to release energy in the absence of oxygen

21
Q

What is the equation for anaerobic respiration?

A

Glucose —> lactic acid (+energy)

22
Q

Why is anaerobic respiration less efficient than aerobic respiration?

A

Glucose is not completely broken down, so less energy is transferred

23
Q

Why can anaerobic respiration lead to muscle fatigue?

A

Lactic acid (product of anaerobic respiration) builds up in muscles, preventing efficient contraction

24
Q

What is fermentation?

A

A type of anaerobic respiration that occurs in yeast cells

25
Q

What is the equation for fermentation?

A

Glucose —> ethanol + carbon dioxide (+energy)

26
Q

Why is the fermentation reaction important?

A

It is used in the production of bread and alcoholic drinks

27
Q

What are the differences between aerobic and anaerobic respiration?

A

Aerobic requires oxygen ; anaerobic does not

Aerobic produces CO2 and water; anaerobic produces lactic acid or ethanol + CO2

Aerobic transfers a greater amount of energy

28
Q

How do muscles store glucose?

A

As glycogen

29
Q

What is metabolism?

A

The sum of all the reactions that take place in a cell or an organism

30
Q

How do cells use the energy transferred by respiration?

A

To continuously carry out enzyme-controlled processes which lead to the synthesis of new molecules

31
Q

Give examples of metabolic reactions

A

Glucose into starch/glycogen/cellulose

Glycerol and fatty acids into lipids

Glucose and nitrate ions into amino acids

Photosynthesis

Respiration

Breakdown of excess proteins into urea