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Z: GCSE Biology > B3 - Life on Earth > Flashcards

B3 - Life on Earth Flashcards

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1
Q

Define what is meant by a ‘species’.

A

Similar organisms that are capable of breeding together to produce fertile offspring

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2
Q

Why does a species have to be able to adapt to its environment?

A

In order to survive and increase its chances of reproducing.

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3
Q

Give some examples as to how a cactus might be adapted to a desert environment.

A
  • By having its leaves reduced to spines to cut down water loss
  • Having a thick outer layer to cut down water loss
  • A deep, wide-spreading root system to obtain as much water as possible
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4
Q

Give some examples as to how a fish might be adapted to survive in water.

A
  • Having gills to take oxygen from water rather than air
  • A streamlined shape and fins to move easily through water
  • A swim bladder (an air-filled sac) to help it maintain position in water
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5
Q

A species may become extinct if it can’t adapt to changes like what? (3 things)

A
  • Increased competition
  • New predators
  • New diseases
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6
Q

True or False?

Organisms live in isolation.

A

False - Organisms do not live in isolation.

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7
Q

What is the purpose of a food chain?

A

To show the feeding relationships between organisms. When animals eat plants or other animals, energy is passed up the food chain.

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8
Q

True or False?

Animals are dependent on each other and their environment for survival.

A

True.

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9
Q

What is the purpose of a food web?

A
  • Show how all the food chains in a habitat are inter-related
  • Show how all the living organisms are dependent on each other
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10
Q

True or False?

Food webs can be complicated because animals’ diets change frequently.

A

False - Food webs can be complicated, but this is due to the fact that many animals have varied diets.

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11
Q

What is meant by the term ‘interdependence’? (HT)

A

When living organisms are dependent on each other to survive.

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12
Q

a) What is one thing that might alter a food web?
b) Give an example of this.
c) What might happen if these changes are too great/significant?

A

a) Environmental changes
b) Less rain could reduce the amount of lettuce and cause reductions in slug numbers.
c) If the changes are too great, organisms will die before they can reproduce, eventually becoming extinct.

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13
Q

Where do all living things on Earth ultimately get their energy from?

A

The Sun.

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14
Q

How is energy transferred from the sun?

A
  • Plants absorb a small proportion of the Sun’s energy through photosynthesis and store the energy in the chemicals that make up their cells (e.g. starch, cellulose)
  • Energy is transferred to other organisms when plants and animals are eaten or decompose.
  • Energy is also transferred when decay organisms feed of dead organisms and the waste products of animals.
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15
Q

What is an ecosystem?

A

An area containing a self-sustained community of organisms and their physical surroundings.

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16
Q

What two things can be found within an ecosystem?

A
  • Autotrophs (producers)

- Heterotrophs (consumers)

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17
Q

What are autotrophs?

A

Self-feeders, for example, plants that make their own food. They are also known as producers.

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18
Q

What are heterotrophs?

A

For example, animals and decay organisms that are unable to make their own food so they get energy by consuming other organisms. For this reason they are also known as consumers.

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19
Q

a) What is the name given to heterotrophs that eat plants?

b) What type of consumers are these?

A

a) Herbivores

b) Primary consumers

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20
Q

a) What is the name given to heterotrophs that eat other animals?
b) What type of consumers are these?

A

a) Carnivores

b) Secondary or tertiary consumers

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21
Q

True or False?

Energy in a food chain can go in more than one direction.

A

False - Energy in a food chain always flows in one direction.

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22
Q

Fill in the gaps.

  • Light energy flows from the _________.
  • The light energy is transferred to an _________, which __________ the energy, uses it for ____________ and stores it in its __________.
  • A ___________ heterotroph eats the _________. Some energy stored in the _________ is transferred and stored in the herbivore’s cells.
  • A ____________ heterotroph eats the _________ heterotroph. Some energy is transferred to the __________ and stored in its cells.
  • Dead organisms are fed on by _________ organisms which are called _____________, such as bacteria and fungi.
A
  • Sun
  • Autotroph, captures, photosynthesis, cells
  • Herbivore, autotroph, plant
  • carnivore, herbivore, carnivore
  • Decay, decomposers
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23
Q

What are dead organisms also fed on by? (HT)

A

Detritivores (e.g. woodlice that can re-enter the food chain.)

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24
Q

a) What can happen at each stage within a food chain to a large proportion of energy? (3 things)
b) What does this mean about the energy availiable at each stage in the chain, and the length of the chain?

A

a) - Lost through heat or respiration
- Excreted as waste products
- Trapped in materials such as bone and fur.
b) This means less energy is availiable at each stage of energy transfer, which means there’s a limit to the length of a food chain.

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25
Q

How can energy efficiency be calculated?

A

Percentage of energy transferred = (input energy divided by output energy) x 100

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26
Q

True or False?

a) All materials are recycled in the natural world.
b) Energy can be created and destroyed, but not changed in type. Energy can be recycled because of this.
c) Energy is always eventually lost from the system, so a constant input is needed (from the Sun)

A

a) True.
b) False - Energy can not be created or destroyed (it can only be changed in type). For this reason it cannot be recycled.
c) True.

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27
Q

How do animals obtain nitrogen?

A

By eating protein in other plants or animals.

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28
Q

How is excess nitrogen removed from the nitrogen cycle?

A

Through excretion, e.g. urea in urine.

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29
Q

When plants and animals are decomposed by decay organisms (e.g. bacteria, fungi) after death, how is the protein broken down?

A

Into nitrogen compounds such as nitrates.

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30
Q

How can nitrogen in the air be removed/fixed? (HT)

A

By nitrogen-fixing bacteria in the soil and in the root nodules of plants like clover and beans (leguminous plants). The nitrogen is then converted into compounds e.g. nitrates.

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31
Q

Nitrates are taken up by plant roots and converted to what? (HT)

A

Protein.

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32
Q

What does the process of denitrification involve?

A

Nitrates are broken down into nitrogen by bacteria in the soil.

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33
Q

How is carbon dioxide removed from the air?

A

By plants in the process of photosynthesis and is incorporated into their cells

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34
Q

What do plants and animals do that releases waste carbon dioxide into the air?

A

Respire.

35
Q

What does combustion (burning) in forest fires and combustion of fossil fuels (e.g. coal, oil, and gas) do to carbon dioxide?

A

Release it into the air.

36
Q

What do decomposer organisms like bacteria and fungi do to release carbon dioxide into the air?

A

Break down dead materials and waste products.

37
Q

True or False?

Microorganisms have a vital role in decomposing organic material and releasing the carbon.

A

True.

38
Q

When measuring environmental change, how can data be obtained? (2 ways)

A
  • Using meters to measure levels of oxygen, carbon dioxide, nitrates and temperature etc.
  • Using living organisms as indicators, e.g. mayfly larvae in rivers need high oxygen levels. Pollution reduces the amount of oxygen so, if mayfly larvae are found in significant numbers, the level of pollution in the river water must be fairly low. Other living indicator organisms include lichen (which don’t grow if the air is polluted) and phytoplankton (the plants found in plankton).
39
Q

When did life on Earth begin?

A

Around 3500 million years ago.

40
Q

The very first living things developed from simple molecules that could copy or replicate themselves. It’s not know how these molecules came about, but what are the two possibilities we know of?

A
  • May have been produced by conditions on Earth at the time (harsh surface conditons, or in deep sea vents)
  • May have arrived on Earth from an external source, e.g. a comet hitting earth.
41
Q

True or False?

Experiments have simulated the harsh conditions on Earth millions of years ago, which led to complex molecules and organisms being formed.

A

False - Experiments have simulated the harsh conditions on Earth millions of years ago, which led to simple organic molecules being formed.

42
Q

True or False?

There’s evidence of simple organic molecules existing in gas clouds in space and in comets.

A

True.

43
Q

a) Evidence suggests that all existing organisms share certain traits such as what?
b) What does this mean about the ancestry of all existing organisms?
c) Give two sources of evidence that support this.

A

a) Cellular structure and genetic code (DNA)
b) This would been that all existing organisms share a common ancestor and evolved from very simple living things.
c) Fossil record; DNA evidence

44
Q

What does fossil evidence show?

A

The history of species and the evolutionary changes over millions of years

45
Q

How can fossils be formed? (3 possibilities)

A
  • Hard parts of organisms that don’t decay easily
  • Parts of animals and plants that haven’t decayed because one or more of the conditions needed for decay were absent, e.g. oxygen or moisture
  • Soft parts of organisms that can be replaced by minerals as they decay. This can preserve traces of footprints or burrows.
46
Q

How does DNA evidence support the common ancestor theory?

A

Analysing DNA of both living organisms and fossils shows the similarities and differences.

47
Q

What does comparing gene sequences reveal about the DNA of some organisms?

A

That the DNA of some organisms can be very similar to organisms that might appear to be very different.

48
Q

What is evolution?

A
  • The slow, continual change within a species over many generations
49
Q

What might evolution results in?

A

A new species that is better adapted to its environment and the extinction of others.

50
Q

When did the theory of evolution come about?

A

1830s

51
Q

Who created the testable theory of evolution?

A

Charles Darwin.

52
Q

What four points is Darwin’s theory of evolution by natural selection based around?

A
  • Individuals show variation (i.e. difference due to their genes)
  • There’s competition for food and mates. Also, disease and predators keep population sizes constant in spite of many offspring.
  • Those better adapted are more likely to survive and reproduce while others die out. This is ‘survival of the fittest’.
  • Survivors pass on genes to their offspring, resulting in an improved organism evolving over generations.
53
Q

What does natural selection rely on?

A

Variation caused by the genes and the environment

54
Q

True or False?

Within natural selection, both genetic variation and environmental variation can be passed on.

A

False - Within natural selection, only genetic variation (usually caused by mutation) can be passed on, and only then if it has occurred in the sex cells. Environmental variation, such as the loss of a finger, cannot be passed on.

55
Q

Which other scientist working in the early 1800s had a theory about evolution?

A

Jean-Baptiste Lamarck.

56
Q

What was Lamarck’s theory of evolution based around?

A

The idea that evolution was caused by a force in the environment, which would cause organisms to change to suit the environment.

57
Q

Why is Darwin’s theory about evolution more widely accepted today than Lamarck’s?

A

Because Darwin’s theory fits with our recent understanding of genes, whereas Lamarck’s theory doesn’t.

58
Q

What is selective breeding?

A

When animals with certain traits are mated to produce offspring with certain desirable characteristics.

59
Q

What is the difference between natural selection and selective breeding?

A

Natural selection is a natural process, whereas selective breeding is carried out by humans for their own purposes, not to suit the environment.

60
Q

a) Is the rate of extinction increasing or decreasing?
b) Why is this?
c) What two things might this reduce?

A

a) Increasing
b) Mainly due to humans
c) Biodiversity and sustainability

61
Q

Why might a species become extinct?

A
  • The introduction of new predators or competition
  • Industrial activities causing global warming
  • Deforestation clears areas, increases carbon dioxide levels and alters the carbon cycle.
62
Q

What is meant by the term ‘biodiversity’?

A

It means the variety of life that exists on Earth. It refers to the many varieties of species and also to the genetic variation of individuals within species.

63
Q

Complete the sentence.

Every time a species becomes extinct…

A

…information stored in its genetic code is lost.

64
Q

What does extinction mean in terms of variety of species on Earth?

A

It means less variety on Earth.

65
Q

Without variety within species, what would happen?

A
  • People would start to run out of food crops

- Shortage of medicine (as medicine is developed from plants and animals)

66
Q

By understanding how our actions can impact on biodiversity, what do scientists hope to discover?

A

Ways to use the Earth’s resources in a sustainable way.

67
Q

Why have all living things been classified into groups based on their similarities and differences in their physical appearance and DNA?

A

Because life is so diverse.

68
Q

What is the name of the large groups that life on Earth is categorised into?

A

Kingdoms.

69
Q

What do kingdoms contain?

A

Many organisms with only a few things in common.

70
Q

What is each kingdom subdivided into?

A

Smaller groups containing fewer organisms with more in common with each other. The smallest of these groups is called species.

71
Q

a) Humans are classified into:
i) the kingdom…?
ii) the species…?

b) Hamsters are classified into:
i) the kingdom…?
ii) the species…?

A

ai) the kingdom Animals
ii) the species Modern Man

bi) the kingdom Animals
ii) the species Golden Hamster

72
Q

What does sustainability mean?

A

That the needs and requirements of people are met without damaging the Earth for future generations. Conserving all species of living things to maintain biodiversity is a key part to this process.

73
Q

Why don’t huge field of a single crop (monoculture) help to maintain biodiversity?

A

Because they don’t provide a base for many food chains or different habitats to support a variety of species.

74
Q

Allowing ‘weed’ plants to grow (organic growing), rather than using herbicides and pesticides, may help to maintain biodiversity. But what are some issues that might come with this?

A

It might mean reduced yields and more expensive food.

75
Q

What question is raised when something is considered to either help maintain or not help maintain biodiversity?

A

Is is affordable economically or commercially?

76
Q

Why are alternative methods for throwing away waste packaging needed?

A

Because companies and individuals are using too much packaging for food and goods and landfill sites are running out of room.

77
Q

What two measures are being put in place to help reduce the amount of packaging that goes to landfill?

A
  • Household and community waste-recycling schemes

- Using packaging made from biodegradable materials instead of oil-based plastics

78
Q

Give some examples of using biodegradable packaging.

A
  • Using cardboard instead of polystyrene as packaging in parcels. Cardboard breaks down relatively quickly or can be recycled.
  • Making carrier bags from cellulose extracted from plants such as potatoes. This makes the bags biodegradable and improves sustainability as it reduced oil usage.
79
Q

Although we can use alternative materials, the best option is to reduce the amount of packaging altogether. Why is this?

A
  • Any material that’s used requires energy to make it, so by not using it there are energy and cost savings.
  • Transport costs can be reduced because less packaging means goods weigh less and take up less room. In turn, less transport means less pollution.
80
Q

How are polar bears adapted to survive to live on the ice in the extremely cold Arctic area around the North Pole?

A
  • Has white fur to blend in with the snow, that is thick enough to keep warm against the cold weather
  • Has very sharp teeth and strong jaws in order to eat food that might be tougher to eat (e.g. seals and sealions)
  • Has large, rough-skinned paws with curved claws so the bear doesn’t sink into the snow
81
Q

Which of the following are heterotrophs and which are autotrophs?

a) Cabbage
b) Human
c) Elm tree
d) Shark
e) Ant
f) Orchid

A

a) A
b) H
c) A
d) H
e) H
f) A

82
Q

Give three reasons why a species may become extinct.

A

Any from:

  • Increased competition
  • New predators
  • Changes to environment
  • New diseases
  • Human activities (e.g. industry, deforestation
83
Q

Genetic variation may allow some species to avoid extinction. How might genetic changes occur?

A

Mutations (in genes)

84
Q

In the nitrogen cycle what is the important of

a) Nitrogen fixation?
b) Denitrification?

A

a) It converts atmospheric nitrogen to nitrates (nitrogen compounds)
b) It converts soil nitrates to atmospheric nitrogen

Z: GCSE Biology (11 decks)

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