7. ECOSYSTEMS
2020
SAY
1. Choose the
correct answer: (1)
The pioneer species in xerarch succession is:
(a)
Phytoplankton (b) Lichen
(c)
Zooplankton (d) Bryophyte
ü Answer:
(b) Lichen
2. Observe the
figure given below and identify the type of age pyramid for human population: (1)
ü Answer:
Expanding/ Broad based age pyramid.
3. Decomposition
has five important steps. (3)
(a)
Write that five
steps.
(b)
Give an example
of a detritivore.
ü Answer:
(a) 1. Fragmentation, 2. Leaching, 3. Catabolism, 4.
Humifaction, 5. Mineralization.
(b) Earthworm.
2020
MARCH
1. Which one of
the following has the largest population in a food chain? (1)
a.
Producers b. Primary consumers
c.
Secondary
consumers d. Tertiary consumers
ü Answer:
(a) Producers
2. What is the
difference between hydrarch succession and xerarch succession? (2)
ü Answer:
Hydrarch succession: It is the succession in water body that leads to
change from hydric to mesic condition.
Xerarch succession: It is the succession in dry areas that leads to
change from xeric to mesic condition.
3. Given below is
a data showing number of individuals and dry weight of different trophic levels
in a grassland ecosystem. Construct,
a.
Pyramid of
number.
b.
Pyramid of
biomass. (2)
|
Trophic level |
Number of individuals |
Dry weight (Kg m-2) |
|
Primary producer |
5,842,000 |
809 |
|
Primary consumer |
7,08,000 |
37 |
|
Secondary consumer |
3,54,000 |
11 |
|
Tertiary consumer |
3 |
1.5 |
ü Answer:
(a) Pyramid of number:
(b) Pyramid of biomass:
2019
SAY June
1. Decomposition
takes place through different steps. The first step is fragmentation. Write the
other four steps. (2)
ü Answer:
Leaching, Catabolism, Humification, Mineralization.
2. Observe the
flowchart showing the stages of a kind of succession. Identify and write the
kind of succession. Fill in the blanks a, b, c. (2)
ü Answer:
Hydrarch (Water succession).
(a) Submerged plant stage.
(b) Reed-swamp stage.
(c) Marsh-meadow stage.
3. Observe the
figure given below: (2)
Name the
nutrient cycle and fill in the blank (a), (b).
ü Answer:
Name of the cycle: Phosphorous cycle.
(a) Producers (Plants)
(b) Detritus
2019
MARCH
1. (a) Identify
the type of ecological pyramid given below. (2)
(b) Pyramid of energy is always upright. Why?
ü Answer:
(a) Pyramid of biomass.
(b) Energy flows from a trophic level to next higher
trophic level, only 10% of energy of a trophic level will be transferred to
next higher trophic level.
2. Detritivores
play a major role in decomposition. (2)
a.
What are
detritivores?
b.
Write an
example for a detritivore.
ü Answer:
(a) Detritivores are the organisms that breaks
detritus to smaller particles.
(b) Earthworm, termites etc.
2018
SAY June
1. In a forest
ecosystem, different plant species are occupied in different vertical levels.
Name such vertical arrangement. (1)
ü Answer:
Stratification.
2. Humification
leads to accumulation of a dark coloured amorphous substance. Identity the substance
and its peculiarities. (2)
ü Answer:
The substance is
Humus.
Peculiarities:
It is highly resistant
to microbial action and decomposition.
Serves as a reservoir
of nutrients.
Release inorganic
nutrients.
3. Hydrach
succession take place in wetter areas and the successional series progress from
'hydric' to 'mesic' condition. List out the stages in correct sequence. (3)
ü Answer:
Phytoplankton (pioneers) → rooted-submerged plants →
rooted-floating angiosperms → free-floating plants → reed-swamp → marsh-meadow
→ scrub → forest (climax community).
2018
MARCH
1. The products of
ecosystem processes are named as ecosystem services. list out any four such
services. (2)
ü Answer:
Ÿ Purify air and water.
Ÿ Reduce global warming, droughts and floods.
Ÿ Maintain biodiversity.
Ÿ Pollinate crops.
Ÿ Provide aesthetic, cultural and spiritual values
etc.
2. Pyramid of
energy is never been inverted. Why? (2)
ü Answer:
When energy flows from
a trophic level to the next higher trophic level, some energy is always lost as
heat at each step.