chapter 9

ANSWER KEY

OBJECTIVE QUESTIONS

1. B
2. B
3. B
4. C
5. C
6. A
7. A
8. D
9. A
10. D

STRUCTURED QUESTIONS

1.(a) i. Zone A                                                                                      

        ii. Avicennia sp.

   (b) i. Pneumatophore

        ii. structure P has openings namely  lenticels for breathing.

   (c )  function of structure Q is to support the plant in the mud in zone B.

   (d) i. has viviparous seeds

         ii. – the seeds, with its geminated radicle falls into the soft mud and

                this prevents the seed from sinking and being carried away by

                the high and low tides of the sea.

             - the seedling can get oxygen from the atmosphere and thus 

               overcomes the problem of insufficient oxygen in the mud.

    (e) mangrove swamps is the confluence of mud and silt and become a

         source of food for the living things of the sea. The mangrove swamps

         are very rich with animals such as crabs, prawns, and others.

    (f) the process of succession takes place because of the prolonged

        deposit of mud and the area increases in height, becoming hard and

        dry.

2. 1. A : Hydrilla sp.

        B : Elodea sp.

        C : Cabomba sp.

     2. A: Lemna sp.

          B: Eichornia sp.

          C: Nelumbium sp.

1. A : Fimbristylis sp.

B : Lepironia sp.

2. A : Ferns

B : Herbal

C: Rainforest

ESSAY QUESTION

• Process X is the process of succession and the area is an  abandoned mining pool.                                                                                (1)
• The pioneer species (plants in the mud) at stage 1 die, decay and are deposited  at the bottom of the pond.                                           (1)
• The settling of humus and soil erosion cause the pond to be shallow.      

(1)

• The  pond is now suited for floating plants(successor plants) such as Lemna, Lotus, water hyacinth and the first succession takes place  .(1)
• The floating plants prevent light from penetrating into the depths of the pond.                                                                                                  (1)
• This prevents the aquatic plants from photosynthesizing and the plants die

(1)

• Finally, all the pioneer plants are replaced by floating plants and the pond gradually becomes shallower because of the accumulation of humus at the bottom of the pond.                                                                     (1)
• The banks of the pond is raised and becomes dry and the floating plants cannot live under these conditions.                                               (1)
• Amphibian plants that can either live in water or on land such as Fimbristylis sp. and Rusiga starts to grow around the area.                   (1)
• Amphibian plants dominate the middle area of the pond                (1)
• Land plant species appear and this is the beginning of a primary forest  (1)
• A climax community, such as a tropical rainforest is finally formed (1)