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Form 3 Biology questions and answers on ecology
Explain how abiotic factors affect plants.
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1.
The chart below shows a feeding relationship in a certain ecosystem. (a) Construct two food chains ending with a tertiary consumer in each case. (b) Which organism has the largest variety of predators in the food web? (c) Name secondary consumers in the food web. (d) Suggest three ways in which the ecosystem would be affected if there was a prolonged drought.
2.
Describe how the quadrant method can be used to estimate the population of various species of plants in a given habitat.
3.
To estimate the population size of crabs in a certain lagoon, traps were laid at random. 400 crabs were caught, marked and released back into the lagoon. Four days later, traps were laid again and crabs were caught. Out of the 374 crabs, 80 were found to be marked. (a) Calculate the population size of crabs in the lagoon using the formula below. N=#frac{ntimesM}{m}# N=Total population of crabs in
4.
Oil can be applied on the stagnant water to control the spread of malaria. (a) How does this practice control the spread of malaria. (b) Give a reason why this practice should be discouraged.
5.
The diagram below represents a feeding relationship in an ecosystem. (a) Write down the food chains in which the guinea fowls are secondary consumers. (b) What would be the short term effects on the ecosystem if lions invaded the area? (c) Name the organism through which energy from the sun enters the food wed.
6.
The diagram below represents a simplified nitrogen cycle. (a) Name the organisms that cause process E (b) Name the process represented by F and H.and J (c) Name the group of organism represented by G.
7.
(a) What is parasitism? (b) Describe how the tapeworm is adapted to a parasitic mode of life.
8.
What is the relationship between leguminous plants and bacteria found in their root nodules?
9.
Give two reasons why primary productivity in an aquatic ecosystem decreases with depth.
10.
State two ways by which the human immuno deficiency virus (H.I.V) is transmitted through sexual intercourse?
11.
The herbivorous mammalian species were introduced into an ecosystem at the same time and in equal numbers. The graph below represents their populations during the first seven years. Study the graph and answer the questions that follow. (a) (i) Which species has a better competitive ability? (ii) Give reason for your (b) Account for the shape of the curve of species A between: (i) One year and
12.
Suggest three reasons why green plants are included in a fish aquarium.
13.
(a) Distinguish between a community and population. (b) Describe how population of grasshoppers in a given area can be estimated.
14.
Explain how the various activities of man have caused pollution of air.
15.
Give a reason why two species in ecosystems cannot occupy the same niche.
16.
State two ways in which some fungi are beneficial to humans.
17.
Explain how birds of prey are adapted to obtaining their food.
18.
The numbers of different types of animals supported by a square kilometer in two terrestrial ecosystems are shown in the table below. (a) (i) Which domestic animal is better adapted to both ecosystems. (ii) Give a reason why the animal named in (a) (i) above is better adapted to the two ecosystems. (b) Why are cattle and sheep fewer I the bush land than in the savannah? (c) (i) Name suitable
19.
Explain how leaves of mesophytes are suited to their functions.
20.
Why are green plants referred to as primary producers in an ecosystem?
21.
The diagram below represents the nitrogen cycle. (a) State the process labeled: A (b) Name the compound represented by B. (c) Name the group of organisms labeled C. (d) (i) Name the group of plants which promote process A (ii) State the part of the plant where process A takes place.. (e) How would excess pesticides in the soil interfere with process A?
22.
(a) Name the bacteria found in the root nodules of leguminous plants. (b) State the association of the bacteria named in (a) above with the.
23.
Explain why the carrying capacity of wild beasts is higher than that for cattle in a given piece of land.
24.
Ascaris lumbricoides is an example for an endoparasite. (a) The name Ascaris refers to (b) State the habitat of the organism. (c) State three ways in which the organism is adapted to living in its habitat.
25.
How are leaves of submerged plants adapted for photosynthesis?
26.
Name the causative agent of typhoid.
27.
(a) What is meant by: (i) Autecology? (ii) Synecology? (b) The number and distribution of stomata on three different leaves are shown in the table below. Suggest the possible habitat of the plants from which the leaves were obtained. (c) State the modifications found in the stomata of leaf C.
28.
How is aerenchyma tissue adapted to its function?
29.
Explain how abiotic factors affect plants.
30.
Name the organism that causes amoebic dysentery.
31.
After an ecological study of feeding relationships, student constructed the food web below. (a) Name the process through which energy from the sun is incorporated into the food web. (b) State the mode of feeding of the birds in the food web. (c) Name two ecosystems in which the organisms in the food web live. (d) From the information in the food web, construct a food chain with the large bird as a
32.
What is the importance of the following in an ecosystem? (a) Decomposers (b) Predation.
33.
The chart below represents a simplified nitrogen cycle. What is represented by X, Y and Z?
34.
(a) Distinguish between pyramid of numbers and pyramid of biomass. (b) Give three reasons for loss of energy from one trophic level to another in the food chain. (c) Describe how the belt transect can be used in estimating the population of a shrub in a grassland.
35.
(a) Name a method that could be used to estimate the population size of the following organisms: (i) Fish in a pond. (ii) Black jack in a garden.
36.
State two ways in which schistosoma species is adapted to parasitic mode of life.
37.
State one way by which HIV/AIDS is transmitted from mother to child.
38.
Describe causes and methods of controlling water pollution.
39.
Describe the three characteristics of a population.
40.
State two characteristic of aerenchyma tissue.
41.
Describe the nitrogen cycle.
42.
Name two benefits that a parasite derives from the host.
43.
(a) Name the causative agents of the following diseases in humans. (i) Typhoid. (ii) Amoebic dysentery. (b) Name the disease in humans caused by plasmodium falciparum.
44.
(a) State three effects of dumping untreated sewage into a river. (b) Name one process that is responsible for loss of energy from one trophic level to the next.
45.
Other than using the quadrant, give two methods of estimating population of grass.
46.
State two ways in which aerenchyma tissues in aquatic plants are adapted to their function.
47.
(a) (i) What is meant by the term biological control? (b) (i) What is eutrophication? (c) Name a substance that is responsible for acid rain.
48.
The diagram below shows a transverse section of a leaf. (a) Name the habitat of the plant from which the leaf is obtained. (b) Give two reasons for your answer in (a) above.
49.
What is meant by the following terms? (a) Habitat. (b) Ecosystem.
50.
The diagram below represents a food web in a certain ecosystem. (a) Name the trophic level occupied by each of the following: (i) Caterpillars. (ii) Small insects. (b) From the food web,construct two food chains which end with lizards as a tertiary consumer. (c) (i) Which organisms have the least biomass in this ecosystem? (ii) Explain the answer in (c) (i) above.
51.
The figure below illustrates a food web in a certain ecosystem. From the food web: (a) Draw the shortest food chain. (b) Identify the organisms with the highest (i) Number of predators (ii) Biomass.
52.
What is meant by the following terms? (a) Ecology. (b) Carrying capacity.
53.
The diagram below represents a certain plant. (a) What is the likely habitat for the plant? (b) Give two reasons for your answer in (a) above.
54.
The table below shows results of a study of three plants C, D and E growing in different habitats. (a) Which one of the plants C, D and E grows in an area of relatively low water availability? (b) Explain your answer in (a) above.
55.
Name the process through which free atmospheric nitrogen is converted into nitrates.
56.
(a) Name the organism that: (i) Causes malaria; (ii) Transmits malaria. (b) State two control measures for malaria.
57.
(a) What is meant by each of the following: (i) Pyramid of biomass? (ii) Pyramid of numbers? (b) During an ecological visit to the Savannah Grassland, students were able to see lions, antelopes, vultures and pastoralists grazing their cattle. Construct a food chain with four consumer levels to illustrate the energy flow in the ecosystem.
58.
Other than using the quadrat, give two methods of estimating population of grass.
59.
Explain the importance of protecting the forest ecosystem with reference to the following: (a) Climate change (b) Biodiversity (c) Biotechnology (d) Water conservation (e) Pollution.
60.
State two limitations of using a quadrat to estimate the population of organisms.
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