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Biology B123 > B3 - Life on Earth > Flashcards

B3 - Life on Earth Flashcards

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1
Q

What is a SPECIES?

A

A GROUP OF ORGANISMS that can BREED together to produce FERTILE OFFSPRING.

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2
Q

What is the benefit of adaptation of organisms to their environment?

A

They are able to SURVIVE to REPRODUCE successfully.

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3
Q

How does a cactus adapt to its environment (4)? How does a camel adapt to its environment?

A

Cactus:
adapted to living in hot dry conditions by storing water in its stem, thick waxy layer to reduce heat loss, small surface area, shallow but extensive roots.

Camel: stores fat in its hump.

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4
Q

How are fish adapted to aquatic environments (4)?

A
  1. They have gills to extract oxygen for respiration.
  2. They have tail fins with a large surface area to propel them through the water. It also stabilises them.
  3. The bodies are streamlined so they can move through the water with as little resistance as possible.
  4. They have a swim bladder that adjust the amount of gas in it to change their depth in water without having to use any energy.
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5
Q

Organisms that live in a habitat are….?

A

Dependent on their environment and other species living there.

They depend on other species for food and compete with each other for resources.

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6
Q

In what ways do animals compete with each other?

In what ways do plants compete with each other?

A

Animals compete with each other for:

  1. FOOD
  2. A MATE
  3. LIVING SPACE and TERRITORIES

Plants compete with each other for:

  1. LIGHT
  2. NUTRIENTS
  3. WATER
  4. SPACE
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7
Q

What is shown on a food web?

A

The feeding relationships of organisms.

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8
Q

What is interdependence?

A

When organisms depend on each other, often in ways other than just providing food.

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9
Q

Because of an organism’s interdependence, any change that affects one species in a food web is likely to….?

A

Affect ALL species in that food web.

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10
Q

What leads to a species becoming extinct?

A

If it is unable to adapt rapidly to a change in the environment, e.g. climate change

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11
Q

The removal of habitats are caused by what?

A

Human activity that threaten species, e.g. Siberian Tiger and the Mountain Gorilla.

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12
Q

What will an introduction of a new species lead to?

A

Extinction if the species is a competitor, predator or causes disease.

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13
Q

Why is extinction very important in food webs?

A

The extinction of a species in a habitat will affect other organisms in the food web and may cause them to also become extinct.

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14
Q

Nearly all organisms on Earth are dependent on what?

A

Energy from the Sun.

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15
Q

What do plants absorb a small percentage of?

Why do they do this?

A

They absorb a small percentage of the energy from sunlight to produce their own food by photosynthesis. They store this energy in chemicals that make up the plant’s cells and tissues.

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16
Q

Almost every food chain begins with…?

A

A plant absorbing energy from the Sun (then other organisms eat the plants for energy)

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17
Q

Along a food chain, what is happening?

A

Energy is transferred from one organism to the next.

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18
Q

Why is some energy lost during energy transfer (3) ?

A
  1. Some parts of the plants aren’t eaten or can’t be digested by the animal.
  2. The animal uses some of the plant’s energy for respiration. During respiration, some energy is lost as heat.
  3. The waste products of the animal, e.g. urine, contains some energy.
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19
Q

Why is the length of a food chain limited?

A

Because energy is lost as each level of a food chain. They are rarely longer than 4/5 organisms.

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20
Q

What is the formula for percentage efficiency of energy transfer at any level?

A

Percentage Efficiency = Energy in Tissues / Energy in Food Eaten x 100

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21
Q

How is energy transfer continued after an organism dies?

A

Microorganisms such as bacteria and fungi feed on dead or decaying organisms. These are called DECOMPOSERS.

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22
Q

What is partly decayed material called?

A

Detritus

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23
Q

What are Detritivores?

A

They feed on detritus and break it down further.

Examples include: earthworms and woodlice.

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24
Q

What is the one and only way that carbon (as carbon dioxide) ENTERS the carbon cycle?

A

CO2 comes from the air. Plants fix this carbon so that it can be used and stored by organisms, by PHOTOSYNTHESIS.

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25
Q

What are the 3 ways in which carbon is RETURNED to the air?

A
  1. As a product of RESPIRATION, when plants and animals release energy from food.
  2. Through the DECOMPOSITION of dead organisms by soil microorganisms such as bacteria and fungi.
  3. By COMBUSTION of organic materials.
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26
Q

How do plants take up proteins?

A

They take up nitrogen from the soil through their roots in the form of nitrogen compounds including NITRATES. These are converted to PROTEINS.

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27
Q

How are nitrates released back into the soil?

A

Animals excrete waste, plants and animals die and are decomposed by microorganisms.

28
Q

What are the two ways in which nitrogen can enter the nitrogen cycle?

A
  1. Nitrogen fixation: Nitrogen molecules in the air are split by lightning. Nitrogen atoms then combine with oxygen in the air to form nitrates which are washed into the soil by rain.
  2. Nitrogen-fixing bacteria, found in the soil and in the roots of leguminous plants (e.g. beans and peas) and convert nitrogen in the air to nitrates.
29
Q

How does nitrogen leave the nitrogen cycle?

A

When DENITRIFYING bacteria convert nitrates in the soil into nitrogen gas. This process is called DENITRIFICATION.

30
Q

How can environmental change be measured (2 types) ?

A

Non-living indicators and living indicators

31
Q

What are 3 examples of non-living indicators?

A
  1. Carbon Dioxide levels (increasing CO2 links with burning more fossil fuels, contributes to global warming)
  2. Temperature levels (to measure the changing climate)
  3. Nitrate levels (increasing nitrates links with sewage or fertilisers entering water - therefore water is polluted)
32
Q

What are 3 examples of living indicators?

A
  1. Phytoplankton (Increase in nitrates in water = increase in phytoplankton → algal bloom → water pollution)
  2. Lichen (sensitive to sulfur dioxide in atmosphere → indicates how clean the air is → more lichen = clean air)
  3. Mayfly Nymphs (sensitive to level of oxygen in water → more mayfly nymphs = water is clean)
33
Q

When did life on Earth begin?

A

3500 million years ago

34
Q

What is ‘evolution’ ?

A

The process of organisms changing over time to become more complex and varied.

35
Q

How did the changes involved in evolution begin with?

A

Variation between individuals.

36
Q

What two causes influence variation?

A
  1. Genetic

2. Environmental

37
Q

Where is the evidence of how organisms evolved over time?

A

In fossils - the remains of organisms or traces of their lives, e.g. footprints and eggs, that have turned into rock.

38
Q

What is a mutation? What will a mutation result in?

A

A change in the genetic information in a cell.

A mutation will result in a change in the characteristics of an organism.

39
Q

How can a mutation be passed to the offspring?

A

If a mutation occurs as sex cells and are produced.

40
Q

What is a ‘gene pool’ ?

A

The alleles of genes that occur in a population of organisms.

41
Q

Why are mutations beneficial to most organisms?

A

It gives them advantages in terms of survival and can be passed on to the next generations.

42
Q

What is Natural Selection?

A

When nature is selecting the most advantageous genes to be passed on.

43
Q

What is the process of Selective Breeding (3) ?

A
  1. Choosing the individuals with the characteristics that are closest to those required.
  2. Breeding these (and preventing other individuals from breeding)
  3. Repeating the process over several generations.
44
Q

How does natural selection result in an organism to be able to survive better (2) ?

A
  1. Reproduction, leading to an increase in the number of individuals displaying the characteristics in later generations.
  2. Competition with other animals, e.g. catching food, escaping predators, resistance to diseases.
45
Q

What are 2 main factors that influence the rate at which evolution takes place?

A
  1. When the environment changes, only those organisms that are best adapted, or can re-adapt, will survive.
  2. If organisms, become isolated (e.g. island), natural selection will act independently on the different populations. Over time, the populations will become distinct and no longer able to reproduce with each other. They will be new species.
46
Q

What 3 pieces of research for evidence of evolution have scientists investigated the relationships between organisms by?

A
  1. Examining the fossil record
  2. Observing similarities/differences in physical features, e.g. skeletons/flowers.
  3. Analysing DNA sequences (more closely related organisms have more DNA sequences in common).
47
Q

What are 3 pieces of evidence support the Theory of Evolution?

A
  1. The simplest organisms are found in earliest rocks. More complex ones appear in younger rocks.
  2. More recent fossils have features that look like adaptations or developments of those of older organisms.
  3. DNA analysis of today’s organisms has confirmed predictions made from the fossil record, including when branches in the tree of life occurred.
48
Q

Who proposed the theory of evolution?

A

CHARLES DARWIN and Alfred Russell Wallace (in 1859)

49
Q

What was the theory of evolution based on?

A

Darwin’s observations on the Galapagos Islands. The islands are volcanic, so organisms on the islands must have arrived, at some point, from the mainland.

50
Q

What did Darwin observe during his research on the theory of evolution?

A

That organisms, such as mockingbirds, were similar but had slight differences to those on the mainland. The mockingbirds were also different from one island to the next.

51
Q

What was Darwin’s ideas about the theory of evolution?

A

Darwin proposed the theory of evolution by NATURAL SELECTION.

Darwin’s ideas that species were not fixed, but could change over time, was the result of his observations and his creative thinking.

52
Q

How did Lamarck’s theory contrast against Darwin’s theory? What did Lamarck suggest?

A

There was no evidence to support Lamarck’s theory.
Lamarck suggested that animals acquired characteristics DURING their lifetime that were then passed on to their offspring.

53
Q

What is Biodiversity? What 3 features does it include?

A

The variety of life on Earth and in different habitats, including:

  1. The number of different species.
  2. The range of different types of organisms (e.g. plants, animals, microorganisms)
  3. The GENETIC VARIATION within each species.
54
Q

Why is maintaining biodiversity important (2) ?

A
  1. The more plants we have available, the more resources there are for developing new food crops.
  2. Many new medicines have been discovered using chemicals produced by living things.
55
Q

How are organisms classified (3) ?

A
  1. A kingdom is a LARGE GROUP with MANY organisms but FEWER characteristics in common.
  2. Moving down from the kingdom, the groups get smaller and have fewer organisms with more characteristics in common.
  3. The level identifying the individual type of organism is the species.
56
Q

Why is the rate of extinction increasing?

A

There is a correlation between the growth of the world’s population and the number of species extinctions. This suggests that a lot of extinction is due to human activities.

57
Q

Why is classification useful?

A
  1. Shows the evolutionary relationships between different organisms.
  2. Evolutionary relationships can be shown for all living and fossilised organisms.
58
Q

What is Sustainability?

A

Meeting today’s needs without harming the environment so that future generations can still meet their own needs.

59
Q

What are 2 ways of maintaining sustainability?

A
  1. Limiting our impact on wildlife, habitats and the environment.
  2. Actively supporting ecosystems and populations of living organisms.
60
Q

What must we do to ensure sustainability?

A

MAINTAIN biodiversity.

The loss of a single species removes a food supply and can have a big impact on the whole ecosystem.

61
Q

What is the only benefit of LARGE-SCALE MONOCULTURE CROP PRODUCTION? What is the major disadvantage?

A

It maximises crop yield.

BUT it’s not SUSTAINABLE. It reduces the biodiversity of the field by growing just one crop species, removing hedgerows to create fields for planting, spraying crops with herbicides and pesticides.

62
Q

Why are disposable products NOT sustainable?

A

They create large amounts of waste that are slow to decompose.

63
Q

What are 3 ways in which we can improve sustainability in PRODUCT MANUFACTURE?

A
  1. Using as little energy as possible and minimal/ recyclable packaging.
  2. Using locally available materials and limiting transport of the product.
  3. Creating as little pollution as possible.
64
Q

What does the Life Cycle Assessment (LCA) do?

A

It tracks the environmental impact of a product.

65
Q

What are the 5 stages in a Life Cycle Assessment?

A
  1. Sourcing of raw materials
  2. Manufacture
  3. Transport
  4. Use
  5. Disposal
66
Q

What kind of packaging do plastic carrier bags now have?

A

BIODEGRADABLE packaging

67
Q

Why is it best to reduce ALL types of packaging?

A

Because even biodegradable materials break down very slowly in landfill sites, produce carbon dioxide, and require energy to produce and transport.

Biology B123 (3 decks)

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