The smallest amount of energy transferred is represented by arrow 2 and largest energy loss by arrow 3.

Zooplankton: They are primary consumers in an aquatic food chain who feeds upon phytoplanktons.

Sometimes climax remains in a particular seral stage without reaching the climax because during ecological succession any change in the abiotic and biotic component may affect the particular seral stage, leading to the preclimax stage before the climax is achieved.
This type of condition occurs presence of seeds and other propagules. This secondarily based area may be invaded by moss or exotic weeds thus exhibiting succession seriously and the climax community is never regenerated. In the case of natural calamities like fire lanslide, floods, change in soil texture.

Stratification refers to the vertical distribution of different species occupying different levels in the ecosystem.
Trees occupy the topmost vertical layer of a forest, shrubs occupy the second layer and herbs and grasses occupy the bottom layers.

(i) The process by which autotrophs convert inorganic materials into organic material with the help of solar energy is called photosynthesis.
\({ { 6CO }_{ 2 } }+12{ { H }_{ 2 }O }\quad \underrightarrow { Light } \quad C{ _{ 6 } }{ { H }_{ 12 } }{ O_{ 6 }+6{ { H }_{ 2 } } }O+6{ { { O } }_{ 2 } }\)
(ii) The green pigment which traps solar energy and converts light energy into chemical energy is chlorophyll.
(iii) The three pigments, i.e. chlorophyll, carotenoids and xenthophylls together form a complex of pigments in the thylakoid membrane. These complexes work for the absorption of light and its transfer to a reaction centre.These complexes are called photosynthetic unit of photosystem or pigment system.

(i) In a pitcher plant the leaves (lamina) are modified to form the pitcher to trap insects.
(ii) Other leaf modifications are:
(a) Tendrils
Whole leaf,e.g.Lathyrus aphaca
 Leaflet,e.g. Pisum sativum
(b) Leaf hooks, e.g.Begonia
(c) Scally leaf, e.g. Ruscus
(d) Leaf blade, e.g. Utricularia
(e) Phyllode, e.g.Acacia

(b) Pyramid is inverted. It is because in pond ecosystem, producers are the smallest organisms while herbivores and carnivores are largest in size. Consequently, there is a gradual increase in biomass of organisms at successive trophic levels.

All organisms/animals which depend directly or indirectly on plants for their food are called consumers.
Consumers are of the following types:
(i) Primary consumers
They are the organisms/animals which depend directly on producers for their food;they are also called as herbivores,e.g. deer, rabbit, zooplanktons.
(ii)Secondary consumers
Secondary consumers are those animals which depend on the primary consumers for their food; they are primary carnivores, e.g frogs,hyena.
(iii)Tertiary consumers
Tertiary consumers are those animals which depend on the secondary consumers for their food;they are the secondary carnivores, e.g. lion, eagle, kite, etc.

1. The pyramid is inverted.
2. Since the biomass of fishes far exceeds that of the phytoplanktons, the pyramid is inverted.

a) (i) Carbon cycle.
(ii) Decomposition of organic wastes by microbes.
(b) Due to deforestation, the amount of carbon dioxide in the atmosphere increases because carbon dioxide is not used up for photosynthesis in the absence of plants.
(c) Carbon dioxide is the major greenhouse gas in the atmosphere; an increase in the amount of CO2 increases the temperature of the atmosphere by its greenhouse effect, i.e. by absorbing the infrared radiation reflected by the earth's surface.
1. The temperature of the earth has increased by /0.6 °C during the past century,atmostly during the last three decades.
2. This rise in temperature can lead to odd climatic changes, called EI Nino effect and produce deleterious changes in the environment.