K.C.S.E Biology Q & A - MODEL 2005PP1QN17
After an ecological study of feeding relationships students 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 quarternary consumer. e) What would happen to the organisms in the food web if bird N migrated? f) Not all the energy from one trophic level is available to the next level. Explain g) (i) Two organisms which play a role in the ecosystems are not included in the food web. Name them. (ii) State the role played by the organisms named in g(i) above. h) i) State three human activities that would affect the ecosystems. ii) Explain how the activities stated in h(i) above would affect the ecosystems.
answers
​a)Photosynthesis
b)Heterotrophic – holozoic c) Small fish pond / dam, rain forests. d) Algae Zoo plankton small fish bird large bird. e)-Snails would increase in number -Bird M would increase in number. -Green plants would decrease in number f) The energy to be passed on from one trophic level to the next is contained in food materials. Most of the food taken in by consumers passed on from one trophic level to the next is consumers passes through the digestive track as undigested matter that is removed as faeces. The digested materials are absorbed in to the bloodstream and conveyed to various tissues of the body. Most of the absorbed food materials are used in respiration, to Produce is lost as heat during sweating, evaporation and transpiration in plants. g)i) Scavengers e.g. vultures Decomposers e.g. bacteria ii) Scavengers feed on dead bodies of herbivores and carnivore / the consumers. -Decomposers act upon the remains of the producers, consumers, & Scavengers causing decay, to release inorganic materials, which are later re-used by producers to make new organic compounds. h) i) -Deforestation -Overgrazing -Soil erosion -Hunting, poaching -Over fishing -Poor waste disposal // Environmental pollution ii) Deforestation Lack of trees leads to reduced number producers in an ecosystem. Overgrazing Many animals eat away and trample the vegetation hence reducing / depleting the number of producers. -Lead to gully erosion hence carrying away some of the underground and crawling animals (Consumers)
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K.C.S.E Biology Q & A - MODEL 2004PP1QN19
Explain how a biotic factors affect plants
answers
Wind.
In windy conditions the rate of transpiration increases; wind disperses fruits/ seeds; is an agent of pollination; acc. Spores for seed. Temperature Changes in temperatures affects the rate of photosynthesis and other biochemical reactions/ metabolic reactions/ enzymatic reactions/ enzymatic reactions, temperature increases rate of transpiration; Lights Plants need light for photosynthesis, some plants need light for flowering/ photoperiodism/ seeds like lettuce require light for germination. Humidity When humidity is low, the rate of transpiration increases; PH Each plant requires a specific pH to grow well/ acidic/ alkalinity/ neutral; Salinity Plants with salt tolerant tissues grow in saline area, plants in estuaries adjust to salt fluctuations; Topography North facing slopes in temperature lands have more plants than south facing slope Plants on windward side have stunted/ distorted growth; Comparisons of mountains and valleys Description of other areas with other topographies e.g. River valley rainfall/ water - Fewer plants in areas/ semi arid and - Water is needed for germination/ is a raw material for photosynthesis/ dissolves/ minerals salts/ provides turgidity for support/ fruits/ seeds Pressure; Variation in atmospheric pressure affect availability of CO+2+ which affects photosynthesis and low pressure increase rate of transpiration; and affect amount of oxygen; for respiration Mineral salts/ trace elements - Affects distribution of plants in the soils - Plants thrive well where there are mineral salts in the soil Plants living in the soil deficient in particular mineral element have special methods obtaining it; for example legumes obtaining from nitrogen by fixation or carnivorous.
K.C.S.E Biology Q & A - MODEL 2003PP1QN16
K.C.S.E Biology Q & A - MODEL 2003PP1QN16
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
Leaf Habitat A B C (c) State the modifications found in the stomata of leaf C.
answers
a) i) study of a single species within a community / ecosystem /habitat / environment.
ii) Synecology? Study of natural communities within an ecosystem b) Leaf Habitat A aquatic / fresh water B Forest; Terrestrial C Arid / semi arid; desert. c) Sunken Hairy Reserved rhythm Small stomatal pore
K.C.S.E Biology Q & A - MODEL 2002PP1QN17
State four advantages of vegetation propagation.
answers
K.C.S.E Biology Q & A - MODEL 2002PP1QN17
Give a reason for grafting in plants
answers
K.C.S.E Biology Q & A - MODEL 2002PP1QN15
Ascaris lumbricoides in an example for an endo – parasite
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.
answers
(a) Genus
(b) Ileum/ colon/ duodenum/ intestines/ of humans or intestines of pig (c) Lack of elaborate elementary canal ( simple guts) can tolerate raw corn Thick cuticle pellicle, reject the outer covering lays many eggs Mouthparts for sucking partly digested food Explain why the carrying of wild animals is higher than that for cattle in a given piece of land.17/6/2020
K.C.S.E Biology Q & A - MODEL 2002PP1QN07​
Explain why the carrying of wild animals is higher than that for cattle in a given piece of land.
answers
K.C.S.E Biology Q & A - MODEL 2002PP1QN05
State two characters that researchers select in breeding programme.
answers
K.C.S.E Biology Q & A - MODEL 2001PP1QN02
Why are green plants referred to as primary producers in an ecosystem?
ANSWERS
K.C.S.E Biology Q & A - MODEL 2000PP1QN17
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 in the bush land than in the savannah? (c) (i) Name suitable methods that were used to estimate the population of: Domestic animals Wild animals (ii) Give a reason why the method named for wild animals in (c) (i) above is suitable (d) state three methods which could be used to determine the diet of wild animals in an ecosystem (e) Name four biotic factors that could have regulated the animal population in both ecosystems (f) State four human activities that affect population of animals in game parks (g) What is the importance of national park to a nation?
answers
​(a) (i) Goat
(ii) It is a grazer and a browser (b) Insufficient grass in bush/ aren’t adapted to eating twigs/ not browsers/ are grazers (c) (i) Domestic animals - total counts Wild animals – total counts; aerial counts/ quadrat/ Belt transect/ capture/ recapture (ii) Analyzing gut counts, studying dentition/ breaks/ claws/ parts (d) Observation Examine droppings Dissecting a sample of animals/ study structure/ nature of digestive System/ size of caecum/ length of intestine/ chamber (e) Irrigation Competition; diseases Predation; human activity/ man accept any correct Parasitism (f) Poaching, cropping/ culling/ licensed spot hunting (g) Pollution; translocation Burning trees, charcoal- deforestation
K.C.S.E Biology Q & A - MODEL 2000PP1QN10
Explain how birds of prey are adapted to obtaining their food.
answers
K.C.S.E Biology Q & A - MODEL 2000PP1QN02
Give a reason why two species in ecosystems cannot occupy the same niche.
answers
K.C.S.E Biology Q & A - MODEL 1999PP1QN17
Explain how the various activities of man have caused pollution of air.
answers
K.C.S.E Biology Q & A - MODEL 1999PP1QN13b
Describe how population of grasshoppers in a given area can be estimated.
answers
​Use the capture and recapture methods; Catch the grasshoppers count and mark using permanent ink; record and release; and allow time 1 to 2 hours; recapture and count the marked and the unmarked; total population is equal to the number of marked and unmarked grasshoppers in the second sample multiplied by number marked grasshoppers in the first sample; divided by the number of grasshoppers marked in the second sample that were recaptured.
K.C.S.E Biology Q & A - MODEL 1999PP1QN13a
Distinguish between a community and population.
answers
K.C.S.E Biology Q & A - MODEL 1999PP1QN05
Suggest tree reasons why green plants are included in a fish aquararium.
answers
K.C.S.E Biology Q & A - MODEL 1998PP1QN15
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 answer (b) Account for the shape of the curve species A between (i) One year and three years (ii) Three years and seven years (c) A natural predator for species A was introduced into the ecosystem. With a reason state how the population of each species would be affected.
answers
(a) (i) Species A;
(ii) The rate of multiplication/ growth in A is faster than of species B (b) (i) One year and three years 1-3 years shortage of resources more suitable environmental Conditions/ such as food space e.t.c resource were not limiting hence the population increased exponentially rapidly; acc correctly named resource e.g food space. (iii) Three years and seven years 3-7 years shortage of resources/ limiting/ birth rate equals death rate; hence the population had become stagnant/ constant; acc; Environmental resistance has set in rej. Incorrect resources e.g PT and T. (c) Species A would decrease (because of there is less competition with species A/ More resources available.
K.C.S.E Biology Q & A - MODEL 1998PP1QN10
Give two reasons why primary productivity in an aquatic ecosystem decreases with depth.
ANSWERS
K.C.S.E Biology Q & A - MODEL 1997PP1QN19
Describe how the tapeworm is adapted to a parasitic mode of life
answers
Has hooks/suckers: for attachment to wall of intestines: long; to increase surface area for absorption of food: award increase in S.A for absorption once. Secretes enzymes/to neutralize digestive enzymes; (mucus inhibitor substance/anti enzymes) Hermaphroditic: to ensure reproductive/ self fertilization. Production of many eggs: to ensure survival
Segment for egg dispersal: More than one host; for transmission: e.g T solium – pig (Intermediate host) T. Saginata. Long to fit in the intestine/ increase surface area for ( flatten) Absorption of food; Anaerobic survive in the gut with low Oxygen
K.C.S.E Biology Q & A - MODEL 1997PP1QN19
What is parasitism?
answers
K.C.S.E Biology Q & A - MODEL 1997PP1QN14
The diagram below represents a simplified nitrogen cycle.
​(a) Name the organisms that cause process E and J
(b) Name the process represented by F and H. (c) Name the group of organism represented by G
ANSWERS
(a) E- Denitrifying bacteria; e.g pseudomonas denitrifications
J- Nitrifying bacteria; Nitrobacteria reject nitrosamines (b) H- Death decay/ decomposition; excretion/ Aminonification putrefaction egestion. F- Nitrogen fixation (c) Plants K.C.S.E Biology Q & A - MODEL 1997PP1QN11
​The following 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 web.
ANSWERS
​(a) Grass→ Grasshoppers → Guinea fowls
Grass→ Termites → Guinea fowls (b) Lions would compete with leopards Gazelle numbers would reduce Grass would increase (c) Grass; K.C.S.E Biology Q & A - MODEL 1996PP1QN 20
A culture of bacteria was incubated in nutrient agar at 350C. Samples were taken at intervals in order to estimate the number of bacteria in the population. The data obtained is shown in the graph below.
​(a) When was the pollution of bacteria 350 million
(b) Account for the shape of the graph between (i) A and B (ii) B and C (iii) C and D (c) Give three reasons for the shape of the curve between D and E (d) (i) Suggest what would happen to the population of the bacteria if the temperature was lowered to 00 after incubating for 12 hours. (ii) Give a reason for your answer in (d) (i) above (e) Give three reasons why it is important to control human population growth rate in Kenya?
ANSWERS
​(a) 10 HRC and 31 HRC
(b) (i) A and B The number of bacteria dividing are few: bacteria are adjusting conditions: few are dying therefore high increase in population (ii) B and C More cells are dividing due to suitable environment/ favorable conditions; few are dying; therefore high increase in population (iii) C and D No population change; number produced is equal to number dying. (c) Accumulation of toxic wastes; that kills bacteria; depletion of nutrients leading to competition of space. (d) (i) The population will remain the same (ii) Temperature not conclusive for division (e) Food to be sufficient for population Social amenities/ education; health services K.C.S.E Biology Q & A - MODEL 1996PP1QN15
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.
Where N = Total population of crabs in the lagoon
n = Total number of crabs in the second catch M = Number of marked crabs during the first m= Number of marked crabs in the second catch
The chart below shows a feeding relationship in a certain ecosystem
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