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GCSE Biology > Bionergetics > Flashcards

Bionergetics Flashcards

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1
Q

What is photosynthesis?

A

Thr process by which plants syndthesis glucose using light energy from the sun (lighy 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

What is the equation for photosynthesis?

A

6CO2 + 6H2O -> C6H12O6 + 6O2
Carbon dioxide + water -> glucose + oxygen

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4
Q

Is photosynthesis endergonic or exergonic 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 CO2 to enter and O2 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 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 the law which describes the relationship between the distance of a light source from a plant and light intensity

A

Inverse square law - light intensity∝1 / distance^2

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16
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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17
Q

What is aerobic respiration?

A

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

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18
Q

What are the equations for aerobic respiration?

A

Glucose + oxygen -> carbon dioxide + water ( + energy)
C6H1206 + 6C02 -> 6CO2 + 6H20 ( + energy)

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19
Q

Where does aerobic respiration occur?

A

mitochondria

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20
Q

Why do organisms require the energy released by respiration?

A

● Synthesis of larger molecules
● Muscle contraction
● Maintenance of body temperature
● Active transport

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21
Q

What is anaerobic respiration?

A

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

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22
Q

What is the equation for anaerobic respiration?

A

glucose –> lactic acid (+ energy)

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23
Q

Why is anaerobic respiration less efficient than aerobic respiration?

A

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

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24
Q

Why can anaerobic respiration lead to muscle fatigue?

A

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

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25
Q

What is an oxygen debt?

A

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

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26
Q

What is fermentation?

A

A type of anaerobic respiration that occurs in yeast cells.

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27
Q

What is the equation for fermentation?

A

Glucose → ethanol + carbon dioxide ( + energy )

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28
Q

Why is the fermentation reaction important?

A

It is used in the production of bread and alcoholic drinks.

29
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.

30
Q

How do muscles store glucose?

A

as glycogen

31
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

32
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.

33
Q

What is metabolism?

A

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

34
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.

35
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

36
Q

What is the photosynthesis rate?

A

The rate at which plants take in carbon dioxide, water and the energy from sunlight to produce glucose and oxygen

37
Q

What is light intensity?

A

A factor that typically increases the rate of photosynthesis

38
Q

What is the LED light source?

A

Is used as it releases less heat compared with other light bulbs

39
Q

What is pondweed?

A

A species of aquatic plant such as Cabomba or Elodea

40
Q

What is the role enzymes in photosynthesis?

A

Photosynthesis is an enzyme-controlled reaction where the enzymes are needed to convert carbon dioxide into glucose

41
Q

What is sunlight?

A

Is needed as an energy source for photosynthesis to occur

42
Q

What is carbon dioxide?

A

Enters the plant through the stomata during gas exchange and is the source of carbon needed to make glucose

43
Q

What is a plateau?

A

Where a graph levels off and no longer increases past a certain point

44
Q

What is the inverse-square law?

A

Light intensity is inversely proportional to the square of the distance from a light source

45
Q

What is the inversely proportional relationship?

A

As the distance of light from a plant increases, the light intensity decreases

46
Q

What is glucose?

A

The main chemical product of photosynthesis that has many different uses in a plant, including respiration

47
Q

What is oxygen?

A

A waste product of photosynthesis that leaves the plant through the stomata of the leaves or can be used for respiration

48
Q

What is water?

A

A reactant needed for photosynthesis to take place, water is absorbed by the roots and is transported by the xylem to reach the leaves where photosynthesis occurs

49
Q

What do you do to test leaves for starch?

A

Plant leaves can be tested for the presence of starch using iodine solution, after the leaf has been intensely heated and submerged in ethanol

50
Q

What are fats and oil?

A

Lipids which can be made from the products of photosynthesis for storage

51
Q

What does metabolism include?

A

The synthesis of new molecules, the breakdown of existing molecules and the process of respiration

52
Q

What is the energy transferred by cellular respiration used for?

A

Is used by organisms for the continual enzyme-controlled processes of metabolism

53
Q

What do enzyme and metabolism do?

A

Enzymes regulate most cellular reactions and are essential for the synthesis and breakdown of molecules

54
Q

How do convert glucose to complex carbohydrates?

A

Glucose can be converted into starch, glycogen and cellulose

55
Q

What is formation of lipid molecules?

A

One molecule of glycerol joins with three fatty acids

56
Q

What is amino acids production?

A

Glucose and nitrate ions form amino acids which are used to make proteins

57
Q

What is protein synthesis?

A

Amino acids join together in specific arrangements to form proteins

58
Q

What is urea excretion?

A

Excess proteins are broken down to form urea for excretion

59
Q

What does digestion need?

A

Requires energy from respiration to break down large insoluble molecules into smaller soluble molecules

60
Q

What does carbohydrates provide?

A

Provide energy for chemical reactions and can break down into sugars

61
Q

What is protein?

A

The building blocks of cells and tissues that can break down into amino acids

62
Q

What is lipids?

A

An energy store of fats and oils that can break down into glycerol and fatty acids

63
Q

What is cellular respiration?

A

Process that releases energy by breaking down glucose and other food molecules

64
Q

What is an exothermic reaction?

A

A reaction that releases energy to its surroundings, usually in the form of heat

65
Q

What is lactic acid?

A

A toxic waste product that is produced during anaerobic respiration in humans and can cause muscle fatigue

66
Q

What is incomplete oxidation?

A

Occurs during anaerobic respiration causing a build up of lactic acid in the muscles

67
Q

What is oxygen debt?

A

The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid

68
Q

What do organisms need energy for?

A

Movement, keeping warm and chemical reactions to make larger molecules

GCSE Biology (7 decks)

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