9. Environment, Evolution & Energy Transfer Flashcards
(101 cards)
1
Q
Why is the human population rising so quickly?
A
Mostly due to modern medicine and farming
2
Q
Why are humans having a greater impact on the Earth than we used to?
A
1) Increasing population -> Pressure on resources
2) Higher standard of living -> More luxuries -> More raw materials and energy needed
3
Q
What effect is human waste having on water?
A
- Sewage and toxic chemicals from industry pollute lakes, rivers and oceans -> Affects plants and animals
- Chemicals used on land can be washed into water -> Eutrophication
4
Q
What effect is human waste having on land?
A
- Toxic chemicals used for farming -> Wash into water
- Burying nuclear waste
- Dumping household waste in landfill sites
5
Q
What effect is human waste having on air?
A
• Smoke and gases released -> Acid rain
6
Q
In what ways do humans reduce the amount of land and resources available to plants and animals?
A
1) Building
2) Farming
3) Dumping waste
4) Quarrying for metal ores
7
Q
What chemicals are used as mineral fertilisers which can cause eutrophication?
A
Nitrates and phosphates
8
Q
When does eutrophication happen?
A
When fertilisers or sewage is leached into rivers and lakes.
9
Q
Describe eutrophication.
A
1) Mineral ions from fertiliser or sewage enter water.
2) Increased concentration of these ions -> Faster growth of algae/plants
3) Water becomes full of plants -> Block light from reaching those lower down -> These can’t photosynthesise -> They die
4) More dead material as food for microorganisms -> Numbers of microorganisms increases
5) Respiration of these depletes oxygen in the water
6) Aerobic organisms die (e.g. fish) die due to reduced oxygen concentration
10
Q
What two things can cause eutrophication?
A
- Sewage
* Fertiliser
11
Q
Why can sewage cause eutrophication?
A
- It contains lots of phosphates from detergents
* It contains lots of nitrates from urine/faeces
12
Q
What is deforestation?
A
The cutting down of forests.
13
Q
Give two reasons why deforestation happens.
A
1) To provide timber -> Building material / Fuel
2) To clear land for farming -> Food / Fuel farming
14
Q
What problems does deforestation in tropical areas lead to?
A
1) More methane in the atmosphere
2) More CO2 in the atmosphere
3) Less CO2 taken in
4) Less biodiversity
15
Q
How does deforestation in tropical areas lead to more methane in the atmosphere?
A
1) Rice is grown in warm, waterlogged conditions -> Ideal for decomposers -> These produce methane
2) Cattle produce methane
16
Q
How does deforestation in tropical areas lead to more CO2 in the atmosphere?
A
1) Burning trees releases CO2
2) Microorganisms feeding on dead wood release CO2 in respiration
17
Q
How does deforestation in tropical areas lead to less CO2 being taken in?
A
Cutting down trees means less CO2 is removed from the atmosphere in photosynthesis.
18
Q
How does deforestation in tropical areas lead to less biodiversity?
A
Cutting down trees destroys habitats for many species, which may become extinct.
19
Q
What is biodiversity?
A
The variety of species in a habitat.
20
Q
What are the problems of reduced biodiversity?
A
There are many products produced by species which are becoming extinct.
For example, newly discovered plants and animals are great source of food, fibres and medicines.
21
Q
What are bogs?
A
Areas of land that are acidic and waterlogged.
22
Q
What happens to plants that die in a peat bog?
A
They cannot decompose fully because there is a lack of oxygen. Instead of releasing the carbon inside into the atmosphere, the partly-rotted plants build up to form peat.
23
Q
What is peat?
A
A brown substance formed when partly-rotted plants build up on acidic, boggy land.
24
Q
What are the reasons for destroying peat bogs?
A
- To use the land as farmland
- The peat can be cut up, dried and used as a fuel
- The peat is also a good compost
25
What happens when a peat bog is destroyed?
The peat begins to decompose, releasing the carbon stored in the plants as CO2.
26
How can people stop the destruction of peat bogs?
They can buy peat free compost to reduce the demand for peat.
27
What is sequestered carbon dioxide?
Carbon dioxide which has been 'locked up' in natural stores.
28
How can carbon dioxide be sequestered?
* Oceans, lakes and ponds
* Green plants -> Stored as carbon compounds
* Peat bogs
29
How is CO2 removed from the atmosphere by plants?
By photosynthesis.
30
How does the atmosphere keep the Earth at a warm temperature?
The gases in it act as an insulating layer. They absorb the heat being radiated out by the sun and re-radiate it back to Earth.
31
What are greenhouse gases?
Gases that prevent heat being radiated off the Earth and out into space.
32
What are the two main greenhouse gases?
* Carbon dioxide
| * Methane
33
What is global warming?
The process by which the Earth is heating up due to an increases in the amount of greenhouse gases in the atmosphere.
34
What are some effects of global warming?
1) Sea levels rising -> Flooding of low-lying places
2) Ice caps melting -> Even higher sea levels
3) Changes to weather -> More extreme weather - drought, hurricanes, etc.
4) Changes to distribution of animal and plant species
5) Reduced biodiversity
6) Changes to migration patterns
35
How could global warming affect distribution of animal and plant species?
* Wider distribution of species that prefer warm conditions
| * Smaller distribution of species that prefer cold conditions
36
Name some ways in which scientists are monitoring climate change.
* Satellites -> Monitor snow and ice cover + Temperature of sea surface
* Recording temperature and speed of ocean currents
* Automatic weather stations -> Atmospheric temperatures
37
What things must be ensured in order for conclusions to be made about climate change happening?
The area monitored must be:
• Large
• Monitored over a long time period
38
Why is evidence for climate change considered generally reliable?
Several scientists get the same result using different methods.
39
What is theory of evolution?
More than 3 billion years ago, life on Earth began as simple organisms from which all the more complex organisms evolved.
40
How can organisms be classified?
By looking at their similarities and differences, then putting them into groups.
41
How are plants, animals and microorganisms classified?
* Plants - Make their own food and are fixed in the ground
* Animals - Move around and can't make their own food
* Microorganisms - Different to plants and animals
42
What are evolutionary relationships?
How all living things are related.
43
What are ecological relationships?
How organisms interact with each other.
44
What do two similar looking species tell us?
• They are likely to have similar genes because they share a recent common ancestor.
• They usually live in the same habitat.
E.g. Dolphins and whales
45
Are two similar looking species always closely related?
No, not necessarily. They may simply be adapted to living in the same habitat.
E.g. Dolphins and sharks
46
What do evolutionary trees show?
The relationship between organisms. The more recent the common ancestor, the more closely the two species are related.
47
What do species with similar characteristics in the same environment suggest?
They may be in competition.
| E.g. Dolphins and sharks
48
What do species with different characteristics in the same environment suggest?
Predator-prey relationships.
| E.g. Dolphins swim in small groups, but herring swim in large shoals -> Dolphins hunt herring
49
Who came up with the idea of evolution by natural selection?
Charles Darwin
50
Explain the theory of evolution by natural selection.
1) Individuals within a species show variation because of differences in genes
2) Individuals with characteristics that make them better adapted to the environment have a better chance of survival and are more likely to breed successfully.
3) So the genes responsible for the useful characteristics are more likely to be passed on to the next generation.
51
When can a species be said to have evolved?
When the whole species has accumulated the gene for a specific characteristic.
52
Why didn't everyone agree with Darwin's theory of evolution?
1) It went against common religious beliefs
2) No knowledge of genes - couldn't explain passing down of characteristics
3) Not enough evidence - no other studies
53
Who developed a different hypothesis about evolution to Darwin's?
Lamarck
54
Explain Lamarck's hypothesis.
1) If characteristics were used a lot by an organism then it would become more developed during its lifetime.
e. g. A rabbit which runs a lot would develop longer legs
2) These acquired characteristics would be passed on to the next generation.
e. g. The rabbit's offspring would have longer legs
55
Was Lamarck's theory wrong?
Yes, generally. Although some evidence is now coming up to suggest that a tiny number of characteristics might be inherited like this.
56
How can a hypothesis be proved or disproved?
Evidence must be found to prove or disprove it.
57
Give some reasons why scientists' hypotheses may be different to each other.
* Different religious beliefs
* Influenced by different people
* Different ways of thinking
58
Why was Lamarck's theory rejected?
Experiments didn't support his hypothesis.
59
Why was Darwin's theory accepted?
The discovery of genetics provided an explanation for his ideas.
60
What are fossils?
Remains of organisms from many thousands of years ago, which are found in rocks.
61
What can fossils tell us?
How much organisms have changed/evolved over time.
62
What are the 3 ways in which fossils can form?
1) From gradual replacement by minerals (most common)
2) From casts and impressions
3) From preservation in places where no decay happens
63
How can fossils form from gradual replacement by minerals?
1) Teeth, shells, bones, etc. don't decay easily and last a long time when buried.
2) They're eventually replaced by minerals as they decay, forming a rock-like substance shaped like the original part.
3) The surrounding sediments also turn to rock, but the fossil stays distinct inside the rock.
64
How can fossils form from casts and impressions?
1) An animal is buried in a soft material like clay.
2) The clay hardens around it and the organism decays, leaving a cast of itself.
3) This can also happen with footprint impressions.
65
Give some examples of things which can be preserved as fossils from casts and impressions.
* An animal's burrow
* Plant's roots
* Footprints
66
How can fossils form from preservation without decay?
1) In amber and tar-pits, there's no oxygen or moisture, so decay microbes can't survive.
2) In glaciers it's too cold for the decay microbes.
3) Peat bogs are too acidic for decay microbes.
Organisms are preserved because they cannot be decayed.
67
What are some hypotheses for how life began?
* In a primordial swamp or under the sea
| * Simple molecules brought on comets
68
Why can't hypotheses about how life began be supported or disproved?
* Many early life forms were soft-bodied -> No fossils
| * Fossils that did form may have been destroyed by geological activity
69
Give some reasons why species may go extinct.
1) Environment changes too quickly
2) New predator
3) New disease
4) Are out-competed for food, etc.
5) Catastrophic event (e.g. asteroid)
6) New species develops
70
What is a species?
A group of similar organisms that can reproduce to give fertile offspring.
71
What is speciation?
The development of a new species.
72
When does speciation occur?
When populations of the same species become so different they can no longer breed to produce fertile offspring.
73
What is isolation and how can it happen?
Where populations of the same species are separated, usually due to a physical barrier.
74
How does speciation happen?
1) Two populations in a species are isolated from each other
2) Each population faces slightly different conditions
3) Each population evolves by natural selection differently, adapting to their environment
4) Eventually, the populations are so genetically different that they cannot breed with each other to produce fertile offspring
5) The two groups are now separate species.
75
What happens to energy, biomass and number of organisms as you move up a stage in the food chain?
* Less energy
* Less biomass
* Fewer organisms (usually!)
76
Give an example of a situation where the number of organisms increases as you move up the food chain.
Several hundred fleas can feed on a single fox.
77
What is each stage in the food chain called?
A trophic level.
78
What do pyramid of biomass show?
The mass of living material at each stage of the food chain. Basically, the mass of all of the organisms on that level put together.
79
What does the bottom bar of a pyramid of biomass show?
The producer
80
Where does the energy for almost all life on Earth come from?
The Sun
81
Why is only very little energy from the Sun used in photosynthesis to produce glucose?
Most of the light energy is:
• Transmitted through the leaves
• Lost heating up the leaves
• Absorbed by non-photosynthetic parts of the leaves
82
How is energy passed through the food chain?
1) Producers use sunlight energy to produce glucose (chemical energy)
2) This energy is passed down through the food chain when the prey is eaten
83
Why is energy and biomass lost along the food chain?
* Respiration - Movement and maintaining body temperature requires glucose to be reacted
* Waste material
* Some material is inedible (e.g. bones)
84
Why is it rare to find food chains with more than 5 trophic levels?
So much energy is lost at each stage that there's not much left to support later organisms.
85
How can you calculate the proportion of energy transferred from trophic level to trophic level?
Proportion of ET = Energy available to next stage / Energy available to previous stage
86
How can the efficiency of food transfer be improved?
1) Reduce the number of stages in the food chain -> Less energy lost at each stage
2) Restrict energy lost by farm animals -> Prevent movement and heat loss
87
For a given area of land, what is the most efficient type of food to produce?
Crops, not animals.
88
What are the advantages of factory farming?
* Cheaper food
* Better standards of living for farmers
* Helps feed an increasing human population
89
What are the disadvantages of factory farming?
1) Sometimes considered cruel
2) Crowded conditions encourage diseases
3) Antibiotics are given to animals (to prevent disease) -> These antibiotics enter humans -> Microbes develop immunity to antibiotics
4) Power from fossil fuels is often used to keep animals warm
5) Intensively farmed animals eat a lot of fish -> Fish stocks are getting low
90
What are some problems caused by food distribution?
* Expensive
| * Bad for the environment -> Fossil fuels burnt to power cars
91
What are the effects of overfishing?
* Less fish for us to eat
* Ocean's food chains affected
* Some species may disappear altogether in some areas
92
What is sustainable food production?
Having enough food without using resources faster than they renew.
93
How can fish stocks be maintained?
* Fishing quotas -> Limits on the number and size of fish that can be caught in certain areas. This prevents overfishing.
* Net size -> Limits on mesh size of the fish net. This reduces the number of 'unwanted' and discarded fish (i.e. ones that are accidentally caught).
94
How does controlling fishing net size help maintain fish stock?
Using bigger mesh size:
• Lets 'unwanted' species escape
• Younger fish escape -> Can reach breeding age
95
Explain how elements cycle through food chains.
1) Living things are made of materials they take from the world around them (e.g. plants turn elements like carbon into complex compounds)
2) These materials are passed up the food chain
3) These materials are returned to the environment in waste products or when organisms die and decay.
4) This breaks the complex compounds down and returns the elements to the start of the cycle.
96
How do materials decay?
They are broken down (digested) by microorganisms.
97
When does decay happen most quickly?
In these conditions:
• Warm
• Moist
• Aerobic (oxygen-rich)
98
What defines a stable community in terms of the element cycle?
The materials that are taken out of the soil and used by plants etc. are balanced by those that are put back in.
99
Remember to revise the carbon cycle diagram.
Pg 98 of revision guide.
100
Describe the carbon cycle.
1) CO2 is removed from atmosphere by plants during photosynthesis. Carbon is used to make carbohydrates, proteins and fats.
2) Plant respiration returns CO2 to atmosphere.
3) Plants are eaten by animals -> Carbon passed down food chain
4) Animal respiration returns CO2 to atmosphere
5) When plants and animals die, detritus feeders and microorganisms feed on them -> Their respiration returns CO2 into atmosphere
6) Animal waste is broken down by detritus feeders and microorganisms
7) Combustion of wood, fossil fuels and plant and animal products releases CO2 into the atmosphere
101
In the carbon cycle, in what ways is CO2 returned to the atmosphere?
* Burning fossil fuels
* Burning plant and animal products
* Plant respiration
* Animal respiration
* CO2 released from decay
