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Unit 6 Ecology > Succession > Flashcards

Succession Flashcards

1
Q

Suggest why the type of plant community growing on bing changes over time. (5 marks) 6 points

A

Succession described:
1. Lichens and mosses are the PIONEER community
2. which are able to grow in little/no soil
3. that breaks rock fragments/forms thin soil
4. Plants with short roots
5. are able to grow in thin soil
6. Idea that changes in soil structure enable trees/shrubs to grow.
General points:
1. Soil able to retain more water
2. As plants lose leaves/decay
3. Ref to organic matter increases
4. Ref to competition effects

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2
Q

After 100 years the community on the bing becomes stable. State the term used to describe this type of community and explain why it’s stable. (4 marks)

A
  1. Climax community
  2. Includes both plants and animals/has high biodiversity/has many species
  3. Ref to interaction between species
  4. Balanced equilibrium of species.
  5. Ref to dominant/codominant plant or animal species
  6. Stable if no change to environment
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3
Q

Population density of birds drops when shrubs are replaced by pine trees but then increase with the change to mixed woodland. Explain why(2 marks) 4 points

A
  1. Pine trees have less food available for birds.
  2. Needles on the woodland floor don’t support as many invertebrates which birds eat
  3. Reduction in the variety of microhabitats/niches.
  4. Mixed woodland has many layers/is more varied that shelters birds/provides nesting sites.
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4
Q

The mixed woodland is the final climax community. Describe and explain 2 ways in which woodland can be damaged by human activities. (4 marks) 8 points 4 pairs

A

(2 pairs only)

  1. Deforestation
  2. Leaves soil exposed to erosion/loss of habitats
  3. Acid rain
  4. Damages leaves/ needles of trees
  5. Global warming/increase in greenhouse gases
  6. Summer drought reduces tree growth
  7. Physical disturbance by recreational activities
  8. Trampling destroys vegetation/habitats
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5
Q

What’s meant by the term succession. (1 marks)

A

Series of changes that occur to the composition of species in the community of organisms present in an area over a period of time.

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6
Q

Describe how to carry out a study to compare the distribution of Honkenya Pebloides on 2 different parts of the island. (4 marks) 7 points

A
  1. Measuring off 2 areas of the same size
  2. Use of a quadrat
  3. Use of random coordinates/sampling
  4. Method of generating random coordinates (using a random no. generator)
  5. Description of estimating abundance (no. of plants/percentage cover)
  6. Several sample sites should be used
  7. Recording quantitative data by a tally chart, graph or a table.
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7
Q

Describe how water availability could be investigated in these 2 parts of the island. (2 marks) 1

A
  1. Using a moisture probe/drying out soil samples
  2. Testing soil around the plants

OR

  1. Idea of using a rain gauge
  2. Collecting water over a period of time
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8
Q

In 1985, the lesser black backed gull colonised the island. A large increase in the no. of species of plants was recorded after these birds colonised this island. Suggest an explanation for this increase in the no. of species of plants. (2 marks) 5 points

A
  1. Birds brought seeds with them
  2. Idea of bird droppings
  3. Adding nutrients to the soil
  4. Therefore supporting growth of more/different plants
  5. Faeces will help maintain soil structure
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9
Q

Explain what climax community means. (2 marks)

A
  1. Idea of final stage/sere/community

2. which is a stable/ self-sustaining community

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10
Q

Suggest why it’s important to conserve rare and endangered species. (2 marks)

A
  1. Conservation of genetic diversity/biodiversity
  2. To prevent extinction
  3. For aesthetic reasons
  4. These plants may be useful for medicines
  5. Other animals depend on these plants as a source of food/habitats
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11
Q

Explain what is meant by the term plagioclimax. (2 marks) ????

A
  1. Idea of a subclimax

2. Reference to a factor/activity e.g. grazing/mowing that maintains the sub climax

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12
Q

Describe how an area of grazed grassland could develop into a woodland community. (4 marks) ???? 7 points

A
  1. Removal of grazer
  2. Allows new/different plants/species to grow/colonise
  3. Ref to competitive effects/changes in soil
  4. Will go through several stages
  5. which is succession (over a period of time)
  6. Ref to climatic climax
  7. Changes in species composition/different food web/chains
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13
Q

Explain what is meant by the term plagioclimax? (2 marks)

A
  1. Idea of a stable commuinity
  2. Prevented from reaching a climatic climax
  3. By human intervention/activity/grazing
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14
Q

Explain why the grassland on the islands might develop into shrub communities after sheep farming stopped. (3 marks) 5 points

A
  1. Ref to succession
  2. Grazing by sheep cuts off tall-growing plants/only allows low-growing plants to survive
  3. When sheep are removed, grazing stops.
  4. A greater variety of seedlings able to grow/arrival of shrubs and bushes
  5. Taller plants outcompete grasses
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15
Q

On some of the islands where sheep farming stopped, the grasslands remained for a longer time before any change started to be noticed. Suggest 2 reasons for this (2 marks)

A
  1. Other grazers present
  2. Seeds of shrubs did not reach some islands
  3. Unsuitable abiotic factor e.g . soil ph, temp
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16
Q

Describe what would happen to the clear areas in forests, over a long period of time, if the nos. of rabbits and deer decreased. (3 marks)

A
  1. Taller growing plants could develop/grow in the clear areas
  2. Loss of low-growing plants/clear zones
  3. Different animals might appear
  4. Ref to secondary succeession
  5. Climax community of taller plants will form
17
Q

Distributions of plants in a forest is affected by many abiotic factors. Name 1 of these factors and suggest how this factor could affect the distribution of the low-growing plants within the clear areas of a forest. (3 marks) ??????

A
  2. 3.
18
Q

Explain what’s meant by the term reproductively-isolated populations of B.Selene. (3 marks)

A
  1. No interbreeding/reproduction/mating between B.Selene
  2. because of geographical/physical barrier
  3. and they have different behaviours
  4. Incompatible genatalia
  5. Each population having a discrete gene pool e.g. restricted gene flow, different mutations, different alleles
19
Q

Suggest why it’s unlikely that any individuals of B.Selene(butterfly found in forest clearings) would survive if the no.s of rabbits and deer decreased. (3 marks)

A
  1. Low-growing plants would die out/taller growing plants out-compete the low growing plants
  2. B.Selene would be unable to feed i.e. no nectar (for adults)
  3. B.Selene unable to lay eggs
  4. No suitable plants for caterpillars to feed on
  5. Very little variation/genetic diversity in a small population

Unit 6 Ecology (10 decks)

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