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1.         a) Capture –recapture method;                                                                                              

            b) Calculate the population of grasshoppers using the above data

                        FM x SC         = 36 x 45;        = 405;

                             MR             =      4

2.         a) Help to breakdown dead organic matter hence reducing bulk; in the recycling of Nutrients;

            b) Regulate the predator – prey population;

3.         a) Grass___________ grasshoppers ____________ birds;                                                   

            b) Not all the energy is transferred from one trophic level to another; some is lost as heat, some

                is used up during metabolism and some is lost when organisms die and decay;

4.         Autecology is the study of population / study of members of a species;                               

            Biomass is the quantity of matter of a given type of organisms at a given trophic level;     

            Or the dry weight of an organism;

5.         – Availability / adequate food supply ;                                                                                 

            – Absence of predations ;

–  Absence of disease; (mark the first two pts                                                                       

6.         (a) Habitat – physical location with asset of condition where an organism lives; while      

     niche is the exact place where an organism occupy and its role in the habitat;

            (b) Producers have a greater biomass than primary consumers since they start the food chain.

                 Inter-trophic energy losses occur in form of heat;

            (c) It is non-toxic; It’s organism specific;

7.         Reduce oxygen supply and hence suffocation and death of plants and animals, clog respiratory surfaces (gills and stomata) leading to death;

8.         (a) Food web;                                                                                                             

(b) Three;

(c) Sun

9.         a) Microscopic plants- mosquito larvae- small fish- large fish- crocodiles                          

            b) Large fish;

10.       a) Owl is nocturnal , white mice are easily seen and predated on, black mice camouflaged/ not

    easily predated on;                                                                                                 

            b) (Theory of) Natural selection;

11.       a) Capture recapture method                                                                                                 

             b)        i)          P = FM x SC


                                    = 725 + 974;


                                    = 5080;

Where FM – First marked

                        SC – Second recapture

                        MR – Marked recapture

                        P     – Population        

            ii) – No fish moves in or out of the area between counts ;

            –  The marked fish mix freely with other fish populations;

            – Marking does not expose the fish to predation ;             – No variation in population size ;    

12.       D                     A                     C                     B                                                                    

(b) – Correct label;

– A,B same size;

– C-largest;

– D- smallest;  

13.       –  Protects delicate internal parts from mage;                                                            

            – prevents excess loss of water (desiccating);

            – provides surfaces for attachment of body muscles / organs;

14.       a) Grass                       Grasshopper                Guinea Fowl;                                                 

              Grass                     Termites                      Guinea Fowl;

            b) – Leopards will decrease;

                – Gazelles will also decrease;

            c) Grass;

15.       Population — all members of one species occupying a particular habitat at a given time;

             Community — all organisms belonging to different species that interact in the same habitat;

16.       – lay down two ropes parallel to each other a meter apart; count the number of shrubs between

the two ropes at marked points; and record the number; repeat the process several times;

Obtain average number; calculate area of the belt transect.                                      

17.       a)         Population = FM X SC                                                                                                          


                        P = 10 X 50    = 500;

                                    4              4

                                                = 125;

            b) No entry or exit of fish;

                        Tags did not influence the general behavior of fish

18.       – they decompose organisms; aid in nutrient circulation                                                       

19.       i) Accumulation of CO2 in the atom                                                                                      

            ii) Increase in environmental temperature

  • Eratic weather changes

20.       – Enzymes amylase digests starch to maltose                                                                        

            – Mucus lubricates food

21.       Due to (stiff) competition for available resources which leads to elimination/exclusion;

22.       a)feeding level;                                                                                              

            b)quaternary  consumer;

             c)sun/source  of energy;

23.       Adaptive radiation/divergent  evolution;                                                                   

24.       i)crab pop= number marked in  1st catch x total no.  in 2nd catch                                         

                         Number marked(recaptured)in second  catch.

                    = 400×360



            ii) Capture mark release recapture/

           Capture-recapture /capture release /recapture;

25.      (a) Suck small crawling insects (from tree trunks):                                                                

            (b) Catching (flying) insects in grass:

26.       (a) Used for the collection of flying specimens such as butterflies;                          

            (b) Used for sucking small insects from barks of trees and under stones;                             p

            (c) Used for trapping crawling insects such as termites;                                                        p

27.       1. Competition;                                                                                                                       p

            2. Emigration;                                                                                                             p

            3. Predation;                                                                                                                            p        4. Parasitism;      

28.       (a) Biotic and abiotic factors (2x ½ =1mk)

             (b) – Feacal analysis

                 – Type of dentition type of beak    (2 x1=2mks)

29.       X – denitrifying bacteria/

            Y – Animals/ herbivores; accept primary consumers

            Z – Nitrogen fixing bacteria (in soil) accept Azotobacter

 30.      a) Check graph                                                                                                                       

  • Labelling axes;;
  • Scale
  • Plotting;
  • Joining (smooth contineas);
  • Identifying the graph;


b)         i) The population of locusts increase with increase in that the amount of rainfall;

            ii) – Increased amount of food;

  • Improve breeding conditions;

c)         – The population of both decreases

            – Less food availability for locusts and hence crows;

d)         i) Quadrat method;

            ii) total counts

e)         i) locusts ____ primary consumers;

               Crows ______ secondary consumers;

            ii) Grass  ____ Locusts ________ crows;

f)         – Grass would increase;

            – Crows would reduce;

g) Wild animals are browzers hence obtain food while cows are grazers hence lack grass

h) Biomass is the total dry weight of organisms at a particular trophic level;

31.       (a) (i) Antelope A;

                 (ii) Reason- Rate of multiplication /reproduction is higher in species A than B;

(b) (i) Sigmoid curve /ogive/s-shaped curve;

                    Accept any one correct

            (ii) PQ- Lag phase /slow growth phase;                     QR- Exponential/log / rapid growth phase;

                        RS – Deceleration phase                                 ST- Stationary/constant growth phase;

(c) (i) Q and R

         Marked with rapid population growth rate; many mature reproducing  organisms/individuals/antelopes; 

                     Absence of environmental resistance;

    (ii) S and T – Growth rate stagnant/birth rate equals to death rate; the ecosystem has attained

                        its carrying capacity/environmental resistance (density dependent) have set-in;

(d) (i) Interspecific;

                (ii) Thin and tall; yellow/pale green; low yield

(e) By occupying different (ecological) niches;

(f) Move swiftly to escape predators; camouflage to avoid noticed by predators; Eyes on the

    side of the head to give them a wide field of view enabling them to keep track of their enemies;

(g) Capture –recapture method,; direct count,

                 Aerial photography

32.       Water- The availability of adequate amounts of water lead to plant growth which

provides food for animals. In aquatic environment, wateris a medium in which gametes are released thus lead to continuity in procreation.

Temperature- Influences the rate of enzyme catalyzed reactions. Therefore, it exerts an influence on almost all activities of plants and animals such as respiration, photosynthesis, growth, transport e.t.c.

Light-Is necessary in plants for photosynthesis as it influences flowering of a wide variety

         of plants, affecting opening and closing of stomata, affect the rate of transpiration.

Salinity- Is the salt content of eater. It varies in aquatic habitat. Fresh water organisms suffer the

                 risk of loosing water.

Humidity – Determines the amount of water loss from a bodies animals and organs of plants;

                     high humidity means less evaporation; and low humidity means high rate of

                     evaporation and transpirations;

pH – It determines if water habitat is acidic or alkaline; PH has a great influence on

              physiological function of organisms affects enzyme concern reactions since

              enzymes operate within a narrow pH ranges

Wind– Wind came physical damage to plants; increase rate of transpiration as air blows

            away; causes migration of insects; wind having gases may acid rain in a region;

           wind is an agent of pollination and dispersal;

33.       (a)                                                                                                                                                                 Grasses                     Caterpillar          Frogs                           Snakes             Hawk                    Grasses                     Squirrel              Hunting dogs              Hawk              Vulture                   Grasses                     Elephant                           Vultures

Grasses                     Caterpillar          Snake                          Hawk

         (b)        Pyramid of numbers.                                                                                                  


            – Increase in number of gazelles and squirrels due to reduced predation leading to

increased  pressure upon the grass;                                                                            

      (d)         During transfer of energy at each feeding level, some amount of energy in form of heat is

lost only about 10% would be transferred from the grains to steers and out of the 10 %

about 1 kg would be transferred to man. The rest would be lost as heat or ingestible


34.       a) i) Slugs; mice;/ Amphids/ caterpillar                                                                                 

            ii) Primary consumers;

            b) i) plants _________ mice _______ snakes __________ Hawks;

               Plants ________ Caterpillar ________ insectivorous birds _______ hawks

            c) Plants ;_________ directly obtain energy from the sun

            Hawks – Loss of energy in form of heat; through process of respiratal/ defaecation/ excretion  

35.       a) A lot of food causes population increase due to high rate of reproduction and immigration resulting in completion for food/ death/ emigration; reducing population; little food leads to competition; leading to emigration/ death; reducing population                            

b) Energy from the sun is trapped by green plants; during photosynthesis; producing chemical energy/ carbohydrates/ food

Green plants are producers/ 1st trophic level; Green plants are eaten by herbivores which are primary consumers/ occupy the second  trophic level, when plants dies and animals die organisms die; saprophytic fungi/ bacteria/ micro organisms feed on them; thus decomposing them into smaller/ simpler substances/ they are decomposers/ detritivores; At all levels some energy is lost; through respiration

36.       a)         A- Ovary                                                                                                                    

                        B- Oviduct/ fallopian tube

                        C- Uterus/ uterine wall

                        D- Cervix

            b)         Produce ova

                        Produce femme hormones/ Estrogen and progesterone

            c)         – Highly vascularized to supply nutrients to foetus/ drain away excretory wastes

                        – Inner wall lined with Endometrium for implantation of fertilized egg/ zygote

                        – Muscular for peristalisis to expel menses during menstruation/ parturition

                        –  Great capacity to expand during  gestation to accommodate developing foetus

            d)         -copulation/ Achieve orgasm in Human male followed by ejaculation

                        – birth canal

37.       a) use the capture -recapture method; capture the grass hoppers; count; and mark using 

            permanent ink; record; releases; and  allow  time(1-24hrs);recapture and  count the marked and  unmarked;

Total population  is  equal to the  number marked and  unmarked grasshoppers in the second sample X number  of  marked grasshoppers  in the first sample ; divided by number of grasshoppers marked  in the second  sample that  were recaptured;

Acc P= FMxSC      


where FM-1st captured

           SC-2nd capture(marked and  unmarked

            MR-marked recaptured

(rej. ½ mark i.e. 10/2=5) acc specified  distance  apart e.g. 3m apart

b. run two  ropes  parallel  to each  other a  meter  apart; counts  of  shrub are  made  between  the two  ropes  at marked points/whole belt  (and  recorded);report  the  process severally(at least 3 times);calculate shrub area of  the belt transect; calculate  shrub population  for whole area;

Rej all shrubs counted

NB shrub pop=average  shrubs per transect x total  area  of  grassland

                       Average area of  belt  transect  (max 3)

38.       (a) (i) Phytoplanktons:                                                                                                             

      (ii) Hawk; and water snake:                                                                                             

(b) – Decrease in phytoplanktons:

                   – Increase in population of small fish:                                                                            

(c) Hawk;- Top predator amount of energy decreases in successive trophic level/energy is lost

                  through   respiration; undigested/unconverted food:                                                        

           (d) Residue is poisonous to man;

                -Kill non- targeted organism / Beneficial organisms:

                -Remains for along time in the ecosystem / pollutes environment:                                    

(e) (i) Causes decomposition/Recycling of nutrients:                                                             

    (ii) Root nodules: have bacterial / Rhizobium sp: to convert free nitrogen: into nitrates in the


(f) Capture – recapture: capture release recaptures:                                                   

(g)  Manufacture food: (OWTTE) to be used by themselves: and all other organisms in the

     ecosystem   ( awls)

39.       Broad/ wide lamina: to Provide a large surface area to trap maximum sunlight or


– Thin lamina; to reduce the distance covered b\ light and carbon (iv) oxide: to reach the                 

    photosynthetic cells/ palisade cells;

– Cuticle; is transparent to allow light reach photosynthetic cells:

– Waterproof climatic cuticle: to reduce water loss/Transpiration:

– Numerous stomata: efficient gaseous exchange: palisade (mesophyll) cells: have numerous

   chloroplasts: for maximum photosynthesis: spongy mesophyll cells: are irregular in shape

    creating large air spaces between: for efficient /free circulating air; Lear veins; have x 1cm 1r 

   transport  of water and mineral salts: and phloem for transport of manufactured food;

– Leaf mosaic: to maximum trapping of sunlight for photosynthesis:

– Guard cells: to control opening and closing stomata: Guard cells have chloroplasts for


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