51.An oak woodland consists of the following organisms in each trophic level:
1st trophic level: oak trees
2nd trophic level: insects and spiders
3rd trophic level: snakes and lizards
4th trophic level: bird
Which of the following shows the relative number of organisms in each trophic level in the
woodland?
Questions 53 and 54 refer to the graph below which shows the distribution of four kinds of green
algae (W,X,Y and Z) at different depths of water in a pond:
53.Whichplant is best adapted to the dim light conditions?
54.The probable relationship between X and Y is
A)predation
B)mutualism
C)competition
D)commensalism
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55.If nitrogen-fixing genes can be transferred from leguminous plant into other crop plants, this can
A)reduce the use of fertilizers/insecticides
B)increase the suger content of the crop plants
C)increase the resistance of crop plants to fungal infections