Life On Earth Flashcards
1
Q
What is a species?
A
A species is a group of organisms which can interbreed to produce fertile offspring.
2
Q
What is a habitat?
A
A habitat is the place where an organism lives.
3
Q
What is a population?
A
A group of organisms of one species is called a population.
4
Q
What is a community?
A
A community is all the living organisms together in an ecosystem.
5
Q
What is an ecosystem?
A
An ecosystem consists of all the living organisms (community) in a particular habitat and non-living components with which they interact.
6
Q
Formula of an ecosystem?
A
Community + non living components = ecosystem
7
Q
What are some examples of an ecosystem?
A
Pond, coral reef, desert, forest, rainforest and swamp.
8
Q
What is biodiversity?
A
Biodiversity is the total variation that exists amongst living things.
9
Q
What is a producer?
A
Producers are organisms that can make their own food. They are usually green plants.
10
Q
What is a consumer?
A
Consumers are organisms that eat other organisms in the food chain (they consume the food).
11
Q
How many groups can a consumer be split into and state the groups?
A
A consumer can be split into 3 groups:
Herbivore
Carnivore
Omnivore
12
Q
What is a herbivore?
A
A organism that only eats plants.
13
Q
What is a carnivore?
A
An organism that only eats animals.
14
Q
What is a omnivore?
A
A omnivore is an organism that eats both plants and animals.
15
Q
What two categories are animals split into?
A
Predators and prey.
16
Q
What is a predator?
A
A predator is an animal that hunts.
17
Q
What is a Prey animal?
A
Prey are animals that are hunted.
18
Q
What are prey animals and what are predator animals?
A
Prey animals are usually the primary consumer while predators are usually the secondary consumers.
19
Q
What is the feeding relationship called?
A
A food chain.
20
Q
What do the arrows in a food chain show?
A
The arrows show the direction of the energy flow.
21
Q
Give an example of a food chain?
A
Grass —> rabbit —> Fox
22
Q
What is a food web?
A
A food web is a diagram that shows interconnecting food chains
23
Q
What is a niche?
A
A niche is the role that an organism plays within a community.
24
Q
What does a niche relate to?
A
It relates to the resources an organism requires in an ecosystem such as: light,nutrients availability, competition, predation, temperature and interactions with other organisms.
25
When does competition occur?
Competition occurs between plants and animals in an ecosystem when resources are in short supply.
26
What sort of things do animals compete for?
Mates, space, water and food.
27
What do plants compete for?
Light, water, space and nutrients.
28
What happens to an organism if it is not successful during competition for food?
They will die.
29
Which type of competition is more intense?
Infraspecific competition between members of the same species. (Members of the same species require the same resources).
30
What are some limiting factors for animals?
Water, food, mates and space.
31
What are limiting factors for plants?
Water, light, nutrients and space.
32
What is interspecific competition?
Occurs amongst individuals of different species for one or a few of the same resources they require.
33
What is Infraspecific competition?
Occurs amongst individuals of the same species and is for all resources.
34
Inter?
Different
35
Intra
Same.
36
What are quadrats used to sample?
Quadrats are used to sample plants and slow moving animals.
37
What is a source of error with quadrats?
The sample taken may not be representative of the whole ecosystem.
38
How can you solve the error with quadrats?
Quadrats should be placed randomly and many quadrats should be placed (repeat= reliability)
39
What are pitfall traps used for?
Pitfall traps are used to sample small invertebrates living on the ground.
40
What are some source of errors with pitfall traps?
Sample taken may not be representative of the whole ecosystem.
Birds may eat the trapped organisms.
Some some animals may eat others or escape.
41
What are ways to fix the errors in a pitfall trap?
Traps should be placed randomly and many traps should be set up.
Cover the pitfall trap with a lid.
Check the traps regularly.
42
Why do we take samples?
Can’t count all the plants and animals in an ecosystem so instead samples that will represent the whole ecosystem are taken.
43
What do samples need to be?
Random
Repeated several times
Use the same technique
44
What is a biotic factor?
A biotic factors are all the factor that affect a species due to activities of living things.
45
What is an abiotic factor?
abiotic factors are non=living factor which affect a species.
46
What is a light meter used for?
How does it work?
Used to measure light intensity in desired area.
Light sensitive panel captures light intensity and measures it on a lux scale.
47
When using a light meter ensure?
It is held steady
No persons shadow is over light panel
Cloud cover is similar for each measurement
Take measurements at the same time of day
48
What is a moisture meter used for?
How is it used.
Used to measure the moisture content of the soil.
A stick is inserted into ground to make a hole then probe is inserted into soil gently so as not to bend or break it.
49
When using moisture meter ensure?
Dry probe between each sample
| Place a mark around the probe to ensure it is inserted to the same depth.
50
What is a pH meter used for?
How is it used?
Used to measure how acidic or alkaline the soil is.
A stick is inserted into ground to make a hole then probe is inserted into soil gently so as not to bend or break it.
51
When using a pH meter ensure?
Clean probe between each sample
| Place mark around the probe to ensure it is inserted to the same depth.
52
What is a thermometer used for?
How is it used?
Used to measure the temperature of the soil or water.
The same way as a pH probe.
53
When using a thermometer ensure?
Place mark around the thermometer to ensure it is inserted to the same depth.
Ensure the thermometer has adequate time to reach temperature of soil.
54
What is a transept line?
A transect line is a line set up to investigate the effect of an abiotic factor on the distribution of an organism. i.e. the effect of light intensity on the distribution of daisies.
55
Biodiversity in an ecosystem can be affected by?
Biotic factors and abiotic factors. These factors either increase or decrease the biodiversity of an ecosystem.
56
What are some biotic factors?
```
Competition for resources
Disease
Food availability
Grazing
Predation
```
57
What are some abiotic factors?
Light intensity
Moisture
pH
Temperature
58
What do scientists use to identify organisms?
Scientists use keys to make it easier to identify organisms that are sampled.
59
What two types of keys are there?
Branched keys and paired statement keys.
60
What is an indicator species?
Indicators species are species that by their presence of absence, indicate environmental quality/ levels of pollution.
61
What are in plant cells?
```
Cell membranes
Cytoplasm
Nucleus
Chloroplast
Vacuol
Cell wall
```
62
What are green plants able to do that animals can’t do?
Green plants can make their own food using light energy from the sun. This process is called photosynthesis.
63
What are green plants called?
Green plants are called producers.
64
What can producers do?
Producers are the only organisms capable of making their own food in the form of carbohydrates.
65
What are carbohydrates?
Carbohydrates are molecules containing carbon, hydrogen and oxygen which are made during photosynthesis.
66
What do plants need?
Plants need carbon dioxide, water, light energy and chlorophyll
67
What do plants make?
Plants produce oxygen and sugar (glucose).
68
What is the equation for photosynthesis?
Carbon + water —> sugar + oxygen
Dioxide (Light)
(Chlorophyll)
69
Carbon dioxide and water are?
Light and chlorophyll
Sugar and oxygen.
Raw materials.
Essential requirements
Products.
70
What two stages does photosynthesis occur in?
Stage 1= light reactions
(Light dependent stage)
Stage 2= carbon fixation
(Temperature dependent stage)
71
Why is stage 1 know as the light dependent stage?
Stage 1 uses light energy from the sun to split water molecules into hydrogen and oxygen.
Stage one is know as photolysis: photo Lysis
Light to split
72
What happens in stage 1?
Light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical energy.
This energy is used to generate ATP.
73
What does stage one do to the ATP?
Stage one produces one molecule of ATP which is used in stage 2.
74
Which raw material is used during stage 1?
Water.
75
Where does the water from photosynthesis come from?
Water is found in the soil.
76
How does the water get into the plant?
Water is obtained by osmosis through the roots of the plant.
77
Which product is produced during stage one?
Oxygen and it diffuses from the cell. The hydrogen from the water is used in the second stage.
78
Stage one reaction?
Light energy is trapped by chlorophyll —> water —> chemical energy (ATP) —> passes second stage
(water—>) Hydrogen —> transported to second stage
(Water—>) Oxygen —> diffuses out of chloroplast
79
What happens to these three things during photolysis:
Oxygen
Hydrogen
ATP?
Oxygen- excess diffuses out of leaf
Hydrogen- transported to stage 2
ATP- used for energy in stage 2
80
Why is carbon fixation know as the temperature dependent stage?
Carbon fixation is a series of enzymes controlled reactions.
Enzymes require an optimum temperature to work best.
It takes place in the chloroplasts.
81
Carbon fixation is also called?
The Calvin cycle
Light independent stage
Temperature dependent stage
82
Which raw material is used during carbon fixation?
Carbon dioxide.
83
Where does the carbon dioxide for photosynthesis come from?
Carbon dioxide is found in the air all around us.
84
How does the carbon dioxide get into the plant?
Carbon dioxide is obtained by diffusion through the tiny pores in the leaf surface.
85
Which product is produced during carbon fixation?
Sugar.
86
What products from stage one are need in stage 2?
Hydrogen and ATP are needed from stage one.
87
What do hydrogen and carbon dioxide do?
Hydrogen and carbon dioxide combine using energy provided by ATP made in stage 1 to produce sugar.
88
What two things can sugar be converted to?
Starch and cellulose.
89
What can the chemical energy in sugar do?
Is available for respiration or can be used to store starch or be made into cellulose from structural support.
90
What is starch?
Starch is a storage molecule.
91
What is cellulose?
Cellulose is a structural molecule used to build cells walls.
92
What is a limiting factor?
A limiting factor is something which is in short supply that prevents photosynthesis occurring at its maximum rate.
93
What are the three limiting factors of photosynthesis?
Light intensity
Carbondale dioxide concentration
Temperature
94
Why would plants photosynthesis more slowly in dim conditions than bright conditions?
When there is more light, there is more energy for photosynthesis to happen.
95
Why will plants photosynthesis more slowly when there is less carbon dioxide?
When there is more carbon dioxide, there is more of the raw material the plant needs to photosynthesis.
96
Why would Temperature affect the rate of photosynthesis?
Photosynthesis is controlled by enzymes which are sensitive to temperature.
97
What happens to enzymes when they are at a higher temperature than their suited temperature?
The enzymes become denatured and photosynthesis cannot continue.
98
What happens when enzymes hit their optimum temperature?
Photosynthesis is at its maximum rate.
99
What happens to the enzymes as the temperature increases?
The rate of photosynthesis increases as the enzymes become more active.
100
What is the impact on plant growth if one of the factors is limiting?
If one factor is limiting then the rate of photosynthesis will decrease.
This causes less sugar to be produced and it’s growth of the plant will slow down.
101
What is a niche?
A niche is the role that an organism plays within a community.
102
What does a niche relate to?
It relates to the resources an organism requires in an ecosystem such as: light,nutrients availability, competition, predation, temperature and interactions with other organisms.
103
When does competition occur?
Competition occurs between plants and animals in an ecosystem when resources are in short supply.
104
What sort of things do animals compete for?
Mates, space, water and food.
105
What do plants compete for?
Light, water, space and nutrients.
106
What happens to an organism if it is not successful during competition for food?
They will die.
107
Which type of competition is more intense?
Infraspecific competition between members of the same species. (Members of the same species require the same resources).
108
What are some limiting factors for animals?
Water, food, mates and space.
109
What are limiting factors for plants?
Water, light, nutrients and space.
110
What is interspecific competition?
Occurs amongst individuals of different species for one or a few of the same resources they require.
111
What is Infraspecific competition?
Occurs amongst individuals of the same species and is for all resources.
112
Inter?
Different
113
Intra
Same.
114
What are quadrats used to sample?
Quadrats are used to sample plants and slow moving animals.
115
What is a source of error with quadrats?
The sample taken may not be representative of the whole ecosystem.
116
How can you solve the error with quadrats?
Quadrats should be placed randomly and many quadrats should be placed (repeat= reliability)
117
What are pitfall traps used for?
Pitfall traps are used to sample small invertebrates living on the ground.
118
What are some source of errors with pitfall traps?
Sample taken may not be representative of the whole ecosystem.
Birds may eat the trapped organisms.
Some some animals may eat others or escape.
119
What are ways to fix the errors in a pitfall trap?
Traps should be placed randomly and many traps should be set up.
Cover the pitfall trap with a lid.
Check the traps regularly.
120
Why do we take samples?
Can’t count all the plants and animals in an ecosystem so instead samples that will represent the whole ecosystem are taken.
121
What do samples need to be?
Random
Repeated several times
Use the same technique
122
What is a biotic factor?
A biotic factors are all the factor that affect a species due to activities of living things.
123
What is an abiotic factor?
abiotic factors are non=living factor which affect a species.
124
What is a light meter used for?
How does it work?
Used to measure light intensity in desired area.
Light sensitive panel captures light intensity and measures it on a lux scale.
125
When using a light mete ensure?
It is held steady
No persons shadow is over light panel
Cloud cover is similar for each measurement
Take measurements at the same time of day
126
What is a moisture meter used for?
How is it used.
Used to measure the moisture content of the soil.
A stick is inserted into ground to make a hole then probe is inserted into soil gently so as not to bend or break it.
127
When using moisture meter ensure?
Dry probe between each sample
| Place a mark around the probe to ensure it is inserted to the same depth.
128
What is a pH meter used for?
How is it used?
Used to measure how acidic or alkaline the soil is.
A stick is inserted into ground to make a hole then probe is inserted into soil gently so as not to bend or break it.
129
When using a pH meter ensure?
Clean probe between each sample
| Place mark around the probe to ensure it is inserted to the same depth.
130
What is a thermometer used for?
How is it used?
Used to measure the temperature of the soil or water.
The same way as a pH probe.
131
When using a thermometer ensure?
Place mark around the thermometer to ensure it is inserted to the same depth.
Ensure the thermometer has adequate time to reach temperature of soil.
132
What is a transept line?
A transect line is a line set up to investigate the effect of an abiotic factor on the distribution of an organism. i.e. the effect of light intensity on the distribution of daisies.
133
Biodiversity in an ecosystem can be affected by?
Biotic factors and abiotic factors. These factors either increase or decrease the biodiversity of an ecosystem.
134
What are some biotic factors?
```
Competition for resources
Disease
Food availability
Grazing
Predation
```
135
What are some abiotic factors?
Light intensity
Moisture
pH
Temperature
136
What do scientists use to identify organisms?
Scientists use keys to make it easier to identify organisms that are sampled.
137
What two types of keys are there?
Branched keys and paired statement keys.
138
What is an indicator species?
Indicators species are species that by their presence of absence, indicate environmental quality/ levels of pollution.
139
What are in plant cells?
```
Cell membranes
Cytoplasm
Nucleus
Chloroplast
Vacuol
Cell wall
```
140
What are green plants able to do that animals can’t do?
Green plants can make their own food using light energy from the sun. This process is called photosynthesis.
141
What are green plants called?
Green plants are called producers.
142
What can producers do?
Producers are the only organisms capable of making their own food in the form of carbohydrates.
143
What are carbohydrates?
Carbohydrates are molecules containing carbon, hydrogen and oxygen which are made during photosynthesis.
144
What do plants need?
Plants need carbon dioxide, water, light energy and chlorophyll
145
What do plants make?
Plants produce oxygen and sugar (glucose).
146
What is the equation for photosynthesis?
Carbon + water —> sugar + oxygen
Dioxide (Light)
(Chlorophyll)
147
Carbon dioxide and water are?
Light and chlorophyll
Sugar and oxygen.
Raw materials.
Essential requirements
Products.
148
What two stages does photosynthesis occur in?
Stage 1= light reactions
(Light dependent stage)
Stage 2= carbon fixation
(Temperature dependent stage)
149
Why is stage 1 know as the light dependent stage?
Stage 1 uses light energy from the sun to split water molecules into hydrogen and oxygen.
Stage one is know as photolysis: photo Lysis
Light to split
150
What happens in stage 1?
Light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical energy.
This energy is used to generate ATP.
151
What does stage one do to the ATP?
Stage one produces one molecule of ATP which is used in stage 2.
152
Which raw material is used during stage 1?
Water.
153
Where does the water from photosynthesis come from?
Water is found in the soil.
154
How does the water get into the plant?
Water is obtained by osmosis through the roots of the plant.
155
Which product is produced during stage one?
Oxygen and it diffuses from the cell. The hydrogen from the water is used in the second stage.
156
Stage one reaction?
Light energy is trapped by chlorophyll —> water —> chemical energy (ATP) —> passes second stage
(water—>) Hydrogen —> transported to second stage
(Water—>) Oxygen —> diffuses out of chloroplast
157
What happens to these three things during photolysis:
Oxygen
Hydrogen
ATP?
Oxygen- excess diffuses out of leaf
Hydrogen- transported to stage 2
ATP- used for energy in stage 2
158
Why is carbon fixation know as the temperature dependent stage?
Carbon fixation is a series of enzymes controlled reactions.
Enzymes require an optimum temperature to work best.
It takes place in the chloroplasts.
159
Carbon fixation is also called?
The Calvin cycle
Light independent stage
Temperature dependent stage
160
Which raw material is used during carbon fixation?
Carbon dioxide.
161
Where does the carbon dioxide for photosynthesis come from?
Carbon dioxide is found in the air all around us.
162
How does the carbon dioxide get into the plant?
Carbon dioxide is obtained by diffusion through the tiny pores in the leaf surface.
163
Which product is produced during carbon fixation?
Sugar.
164
What products from stage one are need in stage 2?
Hydrogen and ATP are needed from stage one.
165
What do hydrogen and carbon dioxide do?
Hydrogen and carbon dioxide combine using energy provided by ATP made in stage 1 to produce sugar.
166
What two things can sugar be converted to?
Starch and cellulose.
167
What can the chemical energy in sugar do?
Is available for respiration or can be used to store starch or be made into cellulose from structural support.
168
What is starch?
Starch is a storage molecule.
169
What is cellulose?
Cellulose is a structural molecule used to build cells walls.
170
What is a limiting factor?
A limiting factor is something which is in short supply that prevents photosynthesis occurring at its maximum rate.
171
What are the three limiting factors of photosynthesis?
Light intensity
Carbondale dioxide concentration
Temperature
172
Why would plants photosynthesis more slowly in dim conditions than bright conditions?
When there is more light, there is more energy for photosynthesis to happen.
173
Why will plants photosynthesis more slowly when there is less carbon dioxide?
When there is more carbon dioxide, there is more of the raw material the plant needs to photosynthesis.
174
Why would Temperature affect the rate of photosynthesis?
Photosynthesis is controlled by enzymes which are sensitive to temperature.
175
What happens to enzymes when they are at a higher temperature than their suited temperature?
The enzymes become denatured and photosynthesis cannot continue.
176
What happens when enzymes hit their optimum temperature?
Photosynthesis is at its maximum rate.
177
What happens to the enzymes as the temperature increases?
The rate of photosynthesis increases as the enzymes become more active.
178
What is the impact on plant growth if one of the factors is limiting?
If one factor is limiting then the rate of photosynthesis will decrease.
This causes less sugar to be produced and it’s growth of the plant will slow down.
179
What does organisms use their energy for?
Movement
Growth
Undigested materials
Heat
180
Can all the energy be passed onto the organism that eats another organism?
In transfers from one level to the next in a food chain, the majority of the energy is lost as heat, movement and undigested materials.
181
How much energy is used for growth?
Only a small quantity (-10%) Of energy is used for growth.
182
What is done to the energy used for growth?
The energy used for growth is passed onto the next level in the food chain.
183
What is a pyramid of numbers?
A pyramid of numbers can be used to show the number of organisms at each stage of a food chain.
184
What is a pyramid of energy?
A pyramid of energy can be used to show the quantity of energy (KJ/m(squared)/year) at each level of a food chain.
185
What has happened to the human population over the past few hundred years?
It has increased.
186
What does the population growth tell us about birth and death rates?
The human population is growing because the birth rate is higher than the death rate.
187
What does the population growth mean for food production?
An increasing human population requires an increased food yield.
188
What can be done to increase food yield?
Food yields can be increased by intensive farming methods such as using fertilisers and pesticides.
189
What do fertilisers do?
Fertilisers provide chemicals such as nitrates which increase crop yield.
190
Why would nitrates help improve crop yield?
Nitrogen in the form of nitrates is needed by all living organisms to make protein.
Protein is used for growth.
Fertilisers can be added to the soil to increase the Nitrate content of the soil.
This increases crop yield.
191
What are nitrates used for?
Nitrates are used to produce amino acids which are synthesised into plant proteins.
192
How do animals get their protein?
Animals consume plants or other animals to obtain amino acids for protein synthesis.
193
Nitrate flow formula?
Nitrates absorbed by plants—> eaten by animals—> which is eaten by another animal.
194
What are pesticides?
Pesticides are chemicals which can be applied to crops. These kill plants (weeds) and animals (insects) that can reduce plant growth.
195
What would happen to the fertiliser if too much was sprayed on the crop (what would happen to the fertiliser if it rained)?
Fertilisers can leach into fresh water, adding extra, unwanted nitrates.
196
What happens if to much nitrates get into the water?
Tiny organisms called algae feed on the nitrates this will increase algal population which can cause algal blooms.
197
What will happen to plants growing in the water if there is an algal bloom?
The algal bloom will reduce light levels by preventing sunlight from reaching the plants under the water. These aquatic plants will die as they will not be able to photosynthesis.
198
What will happen to the algae and the plants when they eventually die?
These dead plants, as well as dead algae, become the food for bacteria which increase greatly in number as there is more food for them.
199
What will the bacteria use up as they multiply and feed on the algae?
As the bacteria feed, they use up large quantities of oxygen, reducing the oxygen availability for other organisms.
200
How do fertilisers affect biodiversity?
Fertilisers increase crop yield, they also decrease biodiversity.
201
What else could be used instead of fertilisers or pesticides?
Genetically Modified Organisms (GM crops) & biological controls
202
What would damage crops and decrease crop yield.
Weeds and other animals (insects).
203
What chemical can be sprayed on crops to overcome damage to crop yields?
Pesticides are chemical which can be applied to crops to kill plants and animals that reduce plant growth.
204
What will happen if pesticides enter food chains?
Why does this happen?
Pesticides sprayed onto crops can accumulate in the bodies of organisms over time if they are not biodegradable.
This happens due to the pesticides being taken up by plants. These plants are eaten by the primary consumer which are eaten by the secondary consumer.
205
What happens in each stage of the food chain if an organism has eaten pesticides crops?
At each stage of the food chain the toxins remain in the tissues of consumers and so the toxicity increases and can reach lethal levels.
206
What is bioaccumulation?
When toxins build up in a food chain.
207
Which species in the food chain is most affected by bioaccumulation?
The species at the top of the food chain are affected most severely.
208
What can be used instead of pesticides to remove pests from crops?
Biological controls.
209
What is a biological control?
Biological control involves using one species or biological agent to control the population size of another species. The organism used is called a biological control agent.
210
An example of a biological control is?
ladybirds (into the crop growing area, the number of pests can be reduced).
211
What is a mutation?
A mutation is a random change to genetic material.
212
What does DNA contain?
Genes that carry instructions for the manufacture of protein. If a mutation occurs in a gene that results in a change to the sequence of DNA bases, then the structure of the protein that is made may also be altered. This could alter an individual’s phenotype.
213
How often do mutations occur?
Mutations are spontaneous, they are usually randomly occurring and at low frequencies (ROLF).
214
What effects can mutations have?
Mutations may be:
Neutral- no effect
Confer an advantage- increased ability to survive and reproduce
Confer disadvantage- decreased ability to survive and reproduce.
215
What can speed up the rate of mutation?
Environmental factors can increase the rate of mutation like;
Radiation - Gamma Ray,Uv, x-ray
Chemicals-Bromine, mustard, gas, nicotine and tar
216
What role do mutations have in evolution?
Mutations are the only source of new variation in living things.
Mutations create new alleles which may be selected during natural selection.
217
What are alleles?
For every gene you have a copy from you mum and a copy from your dad. Different forms of the same gene are called alleles.
218
What is the role of mutation in adaptation?
New alleles produced by mutation can result in plants and animals becoming better adapted to their environment.
219
What is an adaptation?
An adaptation is an inherited characteristic that makes an organism well suited to its environment and niche.
220
Why are adaptations important?
Adaptation are important as they increase an organisms chance of survival and to successfully reproduce in their environment.
221
What are some example of species adapting to their environment?
Polar bear
Lions
Cactus
222
What would cause an organism to have to adapt?
Adaptations occur in response to changing environmental conditions.
223
What do different alleles in mutations do?
Give rise to variation in a population. Variation within a population makes it possible for a population to evolve over time in response to change environmental conditions.
224
What is a selection pressure?
Selection pressures are external agents which affect an organisms’s ability to survive in a given environment.
225
What are types of selection pressures?
Resources availability- presence of sufficient food, habitat (shelter/ territory) and mates.
Environmental conditions- temperature, weather conditions or geographical access.
Biological factors- predators and pathogens (diseases).
226
What alleles would be advantageous within a population?
```
Genes that could be an advantage are:
Speed
Aggression
Resistance to disease
Coat thickness
Coat colour
Quicker reaction
```
227
What is natural selection?
The process of natural selection occurs over millions of years and has given rise to new species.
228
What is evolution?
Evolution is the appearance of new species as a result of natural selection.
229
What is speciation?
Speciation is the formation of two or more species from one original ancestral species.
230
What happens in speciation?
Part of population becomes isolated by an isolation barrier.
Random mutations occur in each sub population.
Natural selection selects different advantageous mutations in each sub population due to different selection pressures.
Each sub population evolves until they become genetically different.
If the barrier is removed, the sub population can no longer interbreed to produce fertile offspring- two new species.
231
What are possible isolation barriers?
Geographical (e.g. rivers, seas, mountains, canyons, etc)
Ecological- barrier caused by adaptation to living conditions such as pH or salinity of water.
Behavioural- barrier caused by differences in timing, location or complexity of mating rituals that prevents members of a population from mating even if they are not geographically separated.
