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Biology > Unit 5 > Flashcards

Unit 5 Flashcards

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1
Q

What is the source of energy for an ecosystem?

A

sunlight

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2
Q

What is the role of producers in an ecosystem?

A

Producers are plants that perform photosynthesis and use light energy to make biological molecules.

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3
Q

What is the role of consumers in an ecosystem?

A

Consumers are animals that cannot make their own biological molecules and need to eat plants (primary consumers) or other animals (secondary/tertiary consumers) to obtain biological molecules.

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4
Q

What is the role of decomposers in an ecosystem?

A

Decomposers are bacteria and fungi that perform saprobiotic decomposition, releasing enzymes onto dead plants, dead animals, and animal waste to break them down and obtain biological molecules.

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5
Q

Why do producers (plants) need biological molecules?

A

Producers need biological molecules for respiration (glucose), storage (starch), and to make cellulose and proteins (amino acids).

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6
Q

Why do consumers (animals) need biological molecules?

A

Consumers need biological molecules for respiration (glucose), storage (glycogen), and to make triglycerides (fatty acids and glycerol) for energy and protection.

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7
Q

Why do decomposers (bacteria/fungi) need biological molecules?

A

Decomposers need biological molecules for respiration (glucose), to make proteins (amino acids), and to form phospholipids (fatty acids and glycerol).

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8
Q

How do organisms carry energy?

A

Energy is mainly carried as glucose, stored as starch in plants and glycogen in animals, with alternative sources being lipids/fats/triglycerides and proteins.

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9
Q

How does energy move through an ecosystem?

A

Energy moves through the food chain, starting with producers and moving to primary consumers, then secondary and tertiary consumers, with decomposers at each trophic level.

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10
Q

Why is all the light energy not utilized by plants in photosynthesis?

A

Only 2% of light energy is used in photosynthesis; some light misses the chloroplast, is reflected, or is of the wrong wavelength.

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11
Q

Why is energy lost along a food chain?

A

Energy is lost due to respiration (as heat), inedible and indigestible parts of organisms, and only 10% of energy is transferred from producer to primary consumer.

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12
Q

What is Productivity?

A

Productivity is the amount of glucose/energy available to organisms, with primary productivity referring to plants and secondary productivity to animals.

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13
Q

What does a Pyramid of Number represent?

A

It represents the number of each type of organism at each trophic level, decreasing as we move up due to energy loss.

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14
Q

What does a Pyramid of Biomass represent?

A

It represents the biomass of each type of organism at each trophic level, with biomass being the mass of living tissue.

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15
Q

What does a Pyramid of Energy represent?

A

It represents the amount of energy found at each trophic level, with energy loss occurring along the food chain.

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16
Q

What are the units for energy?

A

kJ/m2/year

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17
Q

What is photosynthesis?

A

Photosynthesis is the process of using light energy to make glucose and other biological molecules, occurring in plants and algae.

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18
Q

What are adaptations of plants for photosynthesis?

A

Plants have leaves located near the top for light, thin and wide leaves for surface area, veins for water transport, stomata for gas exchange, and palisade cells for maximizing light absorption.

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19
Q

What is the structure of chloroplast?

A

Chloroplasts have a double membrane, thylakoids containing chlorophyll, granum stacks, and stroma fluid.

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20
Q

How does photosynthesis take place?

A

Photosynthesis occurs in two stages: the light-dependent stage on thylakoids and the light-independent stage in the stroma.

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21
Q

Describe the light-dependent stage of photosynthesis.

A

Light hits chlorophyll
chlorophyll absorbs the light if correct wavelength
electrons become excited and are lost from the chlorophyll (photoionisation)
electrons enter an electron carrier system
electrons move down the system releasing energy
this pumps protons from stroma into thylakoid space
protons accumulate in thylakoid space, then diffuse back into stroma
they pass though ATP Synthase which joins ADP and Pi to make ATP (mechanism = chmeiosmosis, process = photophosphorylation)
the electron ends up by joining with NADP to form reduced NADP
light also hits water
causes photolysis (breakdown of water due to light
forms: 4H+, 4e-, O2
the H+ joins with the reduced NADP (now carries a hydrogen atom: H+ and e-)
the e- replaces electrons lost from chlorophyll
O2 given off as waste

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22
Q

Describe the light-independent stage of photosynthesis.

A

involves the calvin cycle
− RuBP (5 carbon) joins with CO2 to make 2 lots of GP (3 carbon)
− the GP is reduced into TP (3 carbon)
− this uses energy from ATP and hydrogen atom from reduced NADP
− the TP can be used to reform RuBP (uses energy from ATP)
− the TP can also be used to form glucose (carbohydrate)
− GP can also be used to form amino acids (proteins) and fatty acids
− TP can also be used to form glycerol
− fatty acids and glycerol will form a lipid
−photosynthesis/calvin cycle = produces all the main biological molecules

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23
Q

What are the limiting factors for photosynthesis?

A

The limiting factors are light, CO2, and temperature, which when increased, can raise the rate of photosynthesis.

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24
Q

What is the compensation point in plants?

A

The compensation point is when the CO2 taken in by photosynthesis equals the amount given out by respiration, resulting in no net gas exchange.

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25
How to measure the rate of photosynthesis?
The rate of photosynthesis can be measured by the amount of CO2 used or O2 produced over a certain time, using a photosynthometer.
26
How does a photosynthometer work?
− measures amount of O2 produced − uses aquatic plants (e.g. elodea), as the O2 produced can be observed and collected − the plant is surrounded in sodium hydrogencarbonate solution (CO2 source) − the plant is kept in darkness before experiment runs (uses up all the O2 in the plant) − as the experiment runs, O2 will be produced, this will be collected in a capillary tube − the amount collected can be measured, this will be converted into a volume by multiplying length of oxygen bubble collected by πr2 − volume of O2 collected can then be divided by time to calculate rate of photosynthesis
27
What is the structure of ATP?
− Adenosine Triphosphate − made from 1 adenosine and 3 phosphates − energy carrier molecule − formation: ADP + Pi (+ energy used) = ATP − condensation reaction using enzyme ATP Synthase − carries energy in its bonds − breakdown: ATP = ADP + Pi (+ energy released) − hydrolysis reaction using enzyme ATPase − delivers energy after breakdown Nucleotide derivative
28
How can ATP be formed?
− photophosphorylation (light dependent stage of photosynthesis) − substrate-level phosphorylation (glycolysis and krebs cycle of respiration) − oxidative phosphorylation (electron transport chain of respiration)
29
What makes ATP a good source of energy?
immediate source = need to only break one bond to release energy (plus bond is weak) manageable source = releases small amount of energy
30
What are the uses of ATP in organisms?
ATP is used for protein synthesis, organelle synthesis, DNA replication, cell division, active transport, metabolic reactions, movement, and maintaining body temperature.
31
What is respiration?
releasing energy from glucose to make ATP ATP will provide energy for life processes occurs in all living organisms
32
What are the two types of respiration?
The two types of respiration are aerobic (with oxygen) and anaerobic (without oxygen).
33
Describe aerobic respiration.
Aerobic respiration occurs in four stages: Glycolysis, Link Reaction, Krebs Cycle, and Electron Transport Chain, primarily producing ATP in the last stage.
34
Glycolysis
Takes place in the cytoplasm of the cell. It uses glucose to make 2 pyruvate, 2 ATP and 2 reduced NAD. Pyruvate enter link reaction ATP made by substrate level phosphorylation Reduced NAD used in electron transport chain
35
Link reaction
Matrix of mitochondria Uses pyruvate to produce acetylcoenzyme A, reduced NAD and CO2. Pyruvate + coenzyme A = acetylcoenzyme A + reduced NAD + CO2
36
37
Describe anaerobic respiration.
Anaerobic respiration occurs without oxygen, relying solely on glycolysis to produce ATP, with byproducts being lactate in animals and ethanol and CO2 in plants/yeast.
38
How to measure the rate of respiration?
The rate of respiration can be measured by the amount of O2 used or CO2 produced over a certain time, using a respirometer.
39
How is NAD reformed in glycolysis?
NAD is reformed from the reduced NAD made in glycolysis.
40
What happens to reduced NAD in animals?
The reduced NAD donates its hydrogen atom (H+/e-) to pyruvate to reform NAD, and the pyruvate becomes lactate (lactic acid).
41
What happens to reduced NAD in plants and yeast?
In plants and yeast, the pyruvate becomes ethanol and CO2.
42
How can the rate of respiration be measured?
By measuring the amount of O2 used or the amount of CO2 produced in a certain time.
43
What is a respirometer?
A device that measures the amount of gas exchange taking place between an organism and the air in a test tube.
44
How does a respirometer work?
It is connected to a manometer; if the organism takes in more gas than it gives out, the liquid in the manometer moves towards the test tube, and vice versa.
45
What are the respiratory substrates?
Carbohydrates, proteins, and lipids.
46
How are carbohydrates used as respiratory substrates?
All forms of carbohydrates (starch/glycogen/lactose/sucrose) are turned into glucose.
47
How are proteins used as respiratory substrates?
Excess amino acids are converted into keto acids, which are then turned into pyruvate and intermediates of the Krebs cycle.
48
How are lipids used as respiratory substrates?
Lipids provide fatty acids and glycerol; fatty acids become acetyl coenzyme A, and glycerol becomes triose phosphate.
49
What is the value of nitrogen to organisms?
Used to make amino acids & proteins and to make nitrogenous bases in DNA.
50
What is the nitrogen cycle?
Nitrogen gas (N2) is converted into ammonium ions (NH4+) by nitrogen-fixing bacteria, which are then nitrified into nitrate ions (NO3-) for plant absorption.
51
What are the two types of nitrogen-fixing bacteria?
Mutualistic and free-living.
52
Where are mutualistic nitrogen-fixing bacteria found?
In the root nodules of leguminous plants.
53
What do free-living nitrogen-fixing bacteria do?
They place NH4+ ions in the soil.
54
What happens to organic material in the nitrogen cycle?
It is broken down by saprobiotic decomposers, releasing ammonia ions (NH4+) back into the soil.
55
What is the value of phosphorus to organisms?
Used to make phospholipids, DNA, and ATP.
56
What is the phosphorus cycle?
Phosphorus is present in sedimentary rock as phosphate ions (PO43-), which are absorbed by plants and returned to the soil through decomposition.
57
What is an agricultural ecosystem?
A description for farming ecosystems aimed at growing crops and raising animals.
58
How are crops intensively farmed for high yield?
By selecting suitable locations, clearing areas, selectively breeding crops, using greenhouses, providing irrigation, adding fertilizers, controlling pests, and practicing crop rotation.
59
What are pests?
Organisms that harm plants/crops, including weeds, insects, and fungi.
60
How can pests be controlled?
Using pesticides or biological control.
61
What are pesticides?
Chemical sprays that kill pests; herbicides for weeds, insecticides for insects, and fungicides for fungi.
62
What are the advantages of using pesticides?
Fast acting and can control the area covered.
63
What are the disadvantages of using pesticides?
Non-specific, non-biodegradable, leading to bioaccumulation and toxicity in higher trophic levels; pests may develop resistance.
64
What is biological control?
Using predators or parasites to control pests.
65
What are the advantages of using biological control?
Specific, does not cause bioaccumulation, pests do not develop resistance, and does not need to be reapplied.
66
What are the disadvantages of using biological control?
Slow acting, may become a pest itself, and cannot control the area covered.
67
What is bioaccumulation?
Pesticides are not biodegradable, accumulating in organisms' tissues and becoming toxic to consumers at higher trophic levels.
68
What is an integrated pest control system?
A system that uses both pesticides and biological control to reduce pesticide use and protect food chains and ecosystems.
69
What minerals do fertilizers provide?
Nitrate, phosphate, and magnesium.
70
What are the two types of fertilizers?
Natural/organic and artificial/chemical.
71
What is the difference between natural and artificial fertilizers?
Natural fertilizers reduce the risk of leaching/eutrophication but release minerals slower, while artificial fertilizers release minerals faster but pose risks of leaching/eutrophication.
72
What is the benefit of ploughing?
Increases air spaces in the soil, supporting aerobic respiration of decomposers and bacteria involved in nitrogen cycles.
73
What is eutrophication?
The process where excess fertilizers leach into water sources, causing algal blooms that deplete oxygen and harm aquatic life.
74
What is the environmental impact of crop farming?
Deforestation reduces species diversity, monoculture depletes soil nutrients, selective breeding reduces genetic diversity, and pollution causes bioaccumulation and eutrophication.
75
How can the environmental impact of crop farming be reduced?
By keeping native trees and hedgerows, practicing polyculture, maintaining genetic diversity, and using biological control and natural fertilizers.
76
How are domestic livestock intensively reared in farming?
By selectively breeding, providing predigested food, administering antibiotics and vaccinations, using steroid hormones, and restricting movement.

Biology (10 decks)

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