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GCSE BIOLOGY > 4 . Bionergetics > Flashcards

4 . Bionergetics Flashcards

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1
Q

What is photosynthesis ?

A

The process by which plants synthesise glucose using light energy from the Sun.
Light energy is converted into chemical energy.

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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 equations for photosynthesis (word)

A

Word: carbon dioxide + water —> glucose + oxygen

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4
Q

Is photosynthesis an endothermic or exothermic reaction, and why?

A

Endothermic - energy is transferred from the environment to chloroplasts by light.

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5
Q

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

A

Using a water plant (eg. Elodea), collect gas bubbles produced during photosynthesis. The gas will relight a glowing splint as it contains oxygen.

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6
Q

Give examples of leaf adaptations which maximise the rate of photosynthesis

A

• Broad leaves - maximise surface area.
• Thin leaves - short diffusion distance.
• Chlorophyll present - trap light energy.
• Veins - transport water to leaves via xylem, remove photosynthesis products via phloem.
• Air spaces - allow CO, to enter and O, to leave.
• Guard cells - control opening of stomata for gaseous exchange and prevent water loss.

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7
Q

What are the four main factors that affect the rate of photosynthesis ?

A

• Temperature
• Light intensity
• Carbon dioxide concentration
• Amount of chlorophyll

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8
Q

How does temperature affect the rate of photosynthesis?

A

Increasing the temperature increases the rate of photosynthesis as the kinetic energy of particles is increased. The rate decreases past a certain temperature as enzymes become denatured.

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9
Q

How does light intensity affect the rate of photosynthesis?

A

Increasing the light intensity increases the rate of photosynthesis until another factor becomes limiting.

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10
Q

How does carbon dioxide concentration affect the rate of photosynthesis?

A

Increasing the carbon dioxide concentration increases the rate of photosynthesis (until another factor becomes limiting) as CO2 is required to make glucose.

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11
Q

How does the amount of chlorophyll affect the rate of photosynthesis?

A

Decreasing the amount of chlorophyll (eg. due to a lack of magnesium) decreases the rate of photosynthesis as chlorophyll is required to absorb light energy.

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12
Q

What is a limiting factor ?

A

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

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13
Q

Explain how you can calculate the rate of photosynthesis by measuring oxygen production

A

• Set up bubble potometer apparatus (pondweed in a sealed tube of water, attached to a capillary tube and a gas syringe).
• Oxygen gas produced causes the bubble in the capillary tube to move. The distance moved by the bubble is used to calculate the volume of oxygen produced.

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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 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 in which glucose reacts with oxygen to release energy which can be used by cells.

17
Q

What are the equations for aerobic respiration ? (Word)

A

Glucose + oxygen → carbon dioxide + water (+energy))

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 an oxygen debt ?

A

The amount of oxygen needed to convert lactic acid into back into glucose after anaerobic respiration.

25
Q

What are the differences between aerobic and anaerobic respiration?

A

• Aerobic requires oxygen; anaerobic does not.
• Aerobic produces CO, and water; anaerobic produces lactic acid or ethanol + CO2:
• Aerobic transfers a greater amount of energy.

26
Q

How do muscles store glucose ?

A

As glycogen

27
Q

What changes take place when muscular activity increases in the body?

A

• Heart rate increases and arteries dilate - increases flow of oxygenated blood to muscles.
• Breathing rate increases and breathing is deeper - increases the rate of gaseous exchange.
• Stored glycogen is converted back into glucose.

28
Q

How is lactic acid transported away from the muscles ?

A

Blood flow through the muscles transports lactic acid to the liver, where it is oxidised back to glucose.

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

32
Q

Lern symbol equations for aerobic respiration + anaerobic respiration

A
33
Q

What is fermentation?

A

A type of anaerobic respiration that occurs in yeast cells

34
Q

What is the equation for fermentation ?

A

Glucose —> ethanol + carbon dioxide (+energy)

35
Q

Why is the fermentation reaction important?

A

It is used in the production of bread and alcoholic drinks

36
Q

What is respiration ?

A

Respiration is when living cells release energy from glucose (food) by producing ATP.

GCSE BIOLOGY (15 decks)

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