Life on Earth Flashcards
(112 cards)
1
Q
What is a species?
A
A species is a group of organisms with similar characteristics that interbreed to produce fertile offspring.
2
Q
What is biodiversity?
A
Biodiversity refers to the number and abundance of species in an area. Ecosystems can have higher biodiversity e.g. rainforest or lower biodiversity e.g. desert
3
Q
What is a population?
A
A population is all the animals or plants of one species living in a particular area.
4
Q
What is a producer?
A
A producer is an organism that is able to produce its own food e.g. plants
5
Q
What is a consumer?
A
A consumer is an animal that must eat food in order to get its energy.
6
Q
What is a herbivore?
A
A herbivore is a consumer that eats plants e.g. cow.
7
Q
What is a carnivore?
A
A carnivore is a consumer that eats other animals.
8
Q
What is an omnivore?
A
An omnivore is a consumer that eats a mixture ofplants and animals e.g. bear
9
Q
What is a predator?
A
A predator is an animal that hunts other animals.
10
Q
What are prey species?
A
A prey species is the animal that is hunted by a predator.
11
Q
What is an ecosystem?
A
An ecosystem consists of all the organisms (the community) living in a particular habitat and the non-living components with which the organisms interact. Ecosystem = community + habitat
12
Q
What is a community?
A
A community is all the populations of organisms in a particular habitat.
13
Q
What is a habitat?
A
The habitat consists of all the non-living components with which organisms interact.
14
Q
What is a food chain?
A
A food chain is a diagram which shows the feeding relationships of organisms living together in a particular habitat.
15
Q
What does a food chain always begin with?
A
A food chain always starts with a producer followed by two or three consumers.
16
Q
What do the arrows in a food chain represent?
A
The arrows in a food chain show the direction of the flow of energy.
17
Q
What is a food chain?
A
A food web is made up of lots of food chains put together.
18
Q
Describe the predator prey cycle in terms of changes in population sizes over time.
A
As a prey species number increases the number of predators also increases, until there are too many predators. Then the number of prey species will begin to decrease resulting in the predator numbers also decreasing. Then the cycle begins again.
19
Q
What does niche mean?
A
A niche is a role an organism plays within a community. It relates to the resources it requires e.g. light and nutrients and its interactions with other organisms in the community. It involves competition and predation and the conditions it can tolerate such as temperature.
20
Q
Give 4 resources that organisms may be in competition for.
A
Organisms will compete for resources they need to survive including:
1. sunlight
2. water
3. food
4.mates
21
Q
What is interspecific competition?
A
Interspecific competition is competition between organisms of different species e.g. zebra and giraffe compete for grass.
22
Q
What is intraspecific competition?
A
Intraspecific competition is competition that occurs between organisms of the same species e.g. two male lions competing for access to the female lions.
23
Q
Which type of competition is the most intense and why?
A
Intraspecific competition is more intense due to the individuals of the same species having exactly the same requirements.
24
Q
How can organisms be identified?
A
Organisms can be identified using a paired statement key.
25
How can plants and slow or non-moving organisms be sampled?
Plants can be sampled using a quadrat.
26
Give 2 ways the estimate produced from use of a quadrat be made more accurate?
1. Ensure enough quadrats are counted to ensure the results represent the area sampled.
2. Use a random number generator to make sure the entire area investigated is represented and to eliminate bias..
27
How can invertebrates be sampled?
Invertebrates can be sampled using a pitfall trap.
28
How can the results of pitfall traps be improved?
1. Cover the pitfall trap loosely to hide the insects from predators and to exclude water.
2. Ensure the pitfall trap is flush with the soil so invertebrates enter easily.
3. Set enough pitfall traps to make sure the results represent the area sampled.
29
What is a biotic factor?
Biotic factors are living factors that can influence population sizes and biodiversity in an ecosystem.
30
List 5 biotic factors.
1. Predation
2. grazing
3. competition
4. disease
5. food availability
31
Which biotic factors decrease biodiversity?
Competition, disease, lack of food and predation all reduce biodiversity.
32
Which biotic factor increases biodiversity?
Grazing increases biodiversity because it keeps the dominant fast growing plants under control and allows the smaller plants to grow.
33
What are abiotic factors?
Abiotic factors are non-living (physical) conditions which can affect biodiversity.
34
List 4 abiotic factors?.
1. Light intensity
2. Soil moisture
3. pH
4. Temperature
35
Describe how to measure light intensity.
Use a light meter and angle it towards the light source (sun). Make sure that you are not blocking the sun from the sensor on the meter.
36
Describe2 ways to measure soil pH.
1. Use a soil pH meter to measure soil pH. Make sure the probe is placed into the soil deep enough and that the probe is cleaned between uses.
2. Mix a soil sample with water. Filter the sample and then test the filtrate with universal indicator to determine the pH.
37
Describe how to measure soil moisture level.
Use a soil moisture meter to measure soil moisture. Make sure the probe is placed into the soil deep enough and that the probe is cleaned between uses.
38
Describe how to measure temperature.
Use a thermometer.
39
Describe how soil moisture can have an affect on where a plant species may grow.
Some plant species can only grow in areas with high soil moisture levels. These species will not be found in areas where the soil moisture levels are too low.
40
What is an indicator species?
An indicator species is an organism whose presence or absence gives information about the level of pollution in the environment.
41
What organism is used as an indicator of air quality?
Lichens. The presence of a wide variety of lichen species indicates low sulfur dioxide levels in the air.
42
Which organisms indicate low oxygen levels in fresh water?
Bloodworms, sludgeworm, rat-tailed maggot.
43
What is photosynthesis?
Photosynthesis is the process by which green plants make their own food. Carbon dioxide from the air and water from the soil are combined in the presence of light energy to produce sugar (glucose) and oxygen.
44
What are the raw materials required for photosynthesis?
Carbon dioxide and water.
45
What are the products of photosynthesis?
Sugar and oxygen.
46
What are the 3 essential requirements for photosynthesis?
1. light
2. chlorophyll
3. enzymes
47
Where in a plant cell does photosynthesis take place?
Photosynthesis takes place in chloroplasts.
48
Name the 2 stages in photosynthesis.
1. Light reactrions
2. carbon fixation
49
What happens during the light reactions?
Light energy is used to split water to produce oxygen and hydrogen.
50
What happens to the oxygen produced during the light reactions?
The oxygen produced diffuses from the cell.
51
What happens to the hydrogen and ATP produced during the light reactions?
The hydrogen and ATP produced in the light reactions is used during carbon fixation.
52
What energy change takes place in the light reactions?
Light energy is converted into chemical energy.
53
What is the chemical energy from the light reactions used to make?
Chemical energy is used to generate ATP from ADP and Pi.
54
How are reactions in carbon fixation controlled?
The reactions in carbon fixation are controlled by enzymes.
55
What products from the light reactions are required for carbon fixation?
Hydrogen and ATP from the light reactions are required for carbon fixation.
56
What is the product of carbon fixation?
Sugar
57
What can the chemical energy in the sugar made during photosynthesis be used for?
The chemical energy in sugar is available to the plant for respiration.
58
What can the sugar produced during photosynthesis be converted into?
Sugar made during photosynthesis can be converted into starch or cellulose.
59
Name the storage carbohydrate that sugar can be converted into.
Starch
60
Name the structural carbohydrate that sugar can be converted into.
Cellulose
61
Describe how a leaf could be tested for the presence of starch.
1. The leaf is boiled to release the starch from the cells.
2.The leaf is placed in ethanol to remove the green chlorophyll. 3.Iodine is placed on the leaf. If the iodine turns blue/black then starch is present.
62
Describe 2 ways to measure the rate of photosynthesis.
1. Count the bubbles of oxygen produced by pondweed over a set time.
2. Measure the volume of oxygen produced by pondweed over time.
63
List the 3 factors that can limit the rate of photosynthesis.
Temperature Light intensity Carbon dioxide concentration (TLC)
64
Describe the effect of increasing temperature on the rate of photosynthesis.
As temperature increases the rate of photosynthesis increases until it reaches a maximum. If the temperature is increased further the rate of photosynthesis decreases.
65
Why does temperature limit the rate of photosynthesis?
Temperature affects the rate of photosynthesis because photosynthesis is controlled by enzymes and enzyme activity is affected by temperature.
66
Describe the effect of increasing carbon dioxide concentration on the rate of photosynthesis.
As carbon dioxide concentration increases the rate of photosynthesis increases until it reaches a maximum. Above this concentration any further increases have no effect as carbon dioxide concentration is no longer a limiting factor.
67
Describe the effect of increasing light intensity on the rate of photosynthesis.
As light intensity increases the rate of photosynthesis increases until it reaches a maximum. Above this light intensity any further increases have no effect as light intensity is no longer a limiting factor.
68
What effect does optimising limiting factors have on plant growth.
By optimising the factors that limit the rate of photosynthesis maximum plant growth can be achieved.
69
How can farmers optimise plant growth in glasshouses?
Farmers can improve plant growth in glasshouses by adding carbon dioxide to the air, heating the glasshouse and adding additional artificial light.
70
What happens to energy as it is passed along a food chain?
When energy is passed from one organism to another in a food chain the majority (90%) of energy is lost
71
List 3 ways that energy is lost from food chains.
1. Movement
2. Heat
3. Undigested or uneaten material (eventually decomposed)
72
What is the energy that is passed on used for?
The 10% of energy that is not lost from the food chain can be used for growth and is therefore available for the next level in the food chain.
73
What is a pyramid of numbers?
A pyramid of numbers is a diagram that shows the total number of organisms at each stage in the food chain. Generally the numbers decrease further up the pyramid but occasionally there can be an irregular shape.
74
Give 2 examples where a pyramid of numbers has an irregular shape.
1.Food chains involving parasites like fleas.
2. Food chains involving large producers like trees.
75
What is a pyramid of energy?
A pyramid of energy is a diagram that shows the energy available at each stage in a food chain. It always decreases as you go along the food chain.
76
What units are used in pyramids of energy?
kJ/m2 /year
77
Why is the demand for food increasing?
As the population increases the demand for food to feed everyone also increases.
78
What is crop yield?
Crop yield is how much food we produce.
79
Give 2 ways that farmers can increase food yield?
Fertilisers and pesticides are used to increase crop yield.
80
Describe how pesticides increase crop yield.
Pesticides increase crop yield by killing plants (weeds) and animals (insects) that reduce the yield of the crop.
81
Describe how fertilisers can increase crop yield.
Fertilisers increase crop yield by providing the plants with chemicals such as nitrate that they need to grow. They increase the nitrate concentration of the soil.
82
Describe how nitrates in fertilisers are used by plants and animals.
1. Nitrates in fertiliser dissolve in water and are absorbed by the roots of plants.
2. The plant cells use the nitrates to make amino acids.
3. Amino acids are used by the plant to make proteins.
4. Animals consume plants or other animals to obtain amino acids for protein.
83
What is eutrophication?
Eutrophication is the ecosystem’s response to excess nitrates.
84
Describe the process of eutrophication.
1 Fertilisers can leach into fresh water, adding extra, unwanted nitrates.
2 This increases algal populations which can cause algal blooms.
3 Algal blooms reduce light levels, killing aquatic plants.
4 These dead plants, as well as dead algae, become food for bacteria which increase greatly in number.
5 The bacteria use up large quantities of oxygen, reducing the oxygen availability for other organisms.
6 Other organisms die.
85
Why does eutrophication cause animals in the water to die?
Excess nitrates from fertilisers can result in death of animals in the water, due to the increased levels of bacteria using up the oxygen that the animals need to survive.
86
Describe an alternative to using fertilisers on crops.
One alternative to fertilisers is genetically modified crops.
87
What are GM crops?
GM crops are crops that have had extra genes added into their DNA. Crops can be genetically modified to allow them to grow without using fertilisers.
88
What is bioaccumulation?
Pesticides that are sprayed onto crops can accumulate (build up) in the bodies of organisms over time. This is called bioaccumulation.
89
What happens to toxic chemicals as they pass through a food chain?
As chemicals get passed along the food chain from one organism to another, they become more toxic and eventually can become lethal.
90
Give 2 alternatives to using pesticides on crops.
Two alternatives to using pesticides are:
1 Genetically modified crops
2 Biological control
91
Describe how crops can be genetically modified so the use of pesticides can be reduced.
Crops can be genetically modified to have extra genes added into their genetic material that mean they produce toxins that kill pests. Pest numbers can be controlled without the need for additional chemicals.
92
What is biological control?
Biological control is an environmentally friendly way of reducing pests through the use of natural predators.
93
Give an example of biological control.
Ladybirds are a good example of biological controls. They eat Aphids, which will destroy many types of plants, commonly roses.
94
What is a mutation?
A mutation is a random and spontaneous change to the genetic material. Mutations occur at a low rate and are the only source of new alleles (genes).
95
Mutations can be classified based on their impact on the individual. What are the 2 types of mutation?
Mutations may be neutral, confer an advantage or a disadvantage to the survival of an individual.
96
What is an advantageous mutation?
A mutation which improves an organism’s chance of survival.
97
What is a neutral mutation?
A mutation that has no impact on an organism’s chance of survival.
98
What is a disadvantageous mutation?
A mutation that decreases an organism’s chance of survival.
99
What could increase the rate of mutation?
Radiation (e.g. UV rays and x-rays) and some chemicals (e.g. mustard gas) are mutagenic agents. These can increase the rate of mutations.
100
Mutations are the only source of new alleles. Why is this important to evolution?
New alleles produced by mutations can result in plants and animals becoming better adapted to their environment. It increases genetic variation.
101
Why is variation important?
Variation within a population makes it possible for a population to evolve over time in response to changing environmental conditions.
102
What is an adaptation?
An adaptation is an inherited characteristic that makes an organism well suited to survival in its environment/niche.
103
What is natural selection?
Natural selection or Survival of the Fittest is the gradual change of a species over time to become better adapted to their environment.
104
Detail the 5 stages in natural selection.
1 Species produce more offspring than the environment can sustain.
2 Struggle for survival (competition) occurs due to selection pressures (e.g. predation or disease).
3 The best adapted individuals in a population survive and reproduce, passing on their favourable alleles that confer the selective advantage.
4 These alleles increase in frequency within the population.
5 Gradually the whole population changes to possess the genes that give the population a selective advantage.
105
What is a selection pressure?
A selection pressure is a factor such as predation or disease that affects a population, resulting in the death of some individuals and survival of others.
106
What is speciation?
Speciation is the formation of two or more species from one original species.
107
Describe the 3 main stages in speciation.
1 Isolation: populations become isolated from each other. After a very long period of time the isolated sub-populations have changed so much genetically that they can no longer interbreed to produce fertile offspring. This shows a new species has been formed and speciation has occurred.
2 Mutations: different mutations occur in each sub-population.
3 Natural Selection: selects for different mutations in each group, due to different selection pressures.
108
Why are isolation barriers important in speciation?
Isolation barriers are important as they prevent interbreeding between the two sub-populations.
109
Name the 3 types of isolation barriers.
1 Geographical
2 Ecological
3 Behavioural
110
Give examples of geographical isolating barriers.
Rivers, mountains, oceans
111
Give examples of ecological isolating barriers.
Soil pH, temperature, soil moisture.
112
Give examples of behavioural isolating barriers.
Mating displays/calls, whether the individuals are nocturnal or active in the daytime.
