Q. Describe two ways in which decomposers contribute to the ecosystem?
Answer: Decomposers change wastes ( poop of the organisms) and dead
organisms into usable nutrients. The nutrients are then made available to other
organisms in soil and water and link the biotic and abiotic components of an
ecosystem.
Q. Describe the flow of energy from the sun to a wolf.
Sun
Plants and trees
deer
wolf
Q. What happens to most of energy the energy from sun that is trapped by
plants?
Ans. In plants, these energy factories are called chloroplasts. They collect energy
from the sun and use carbon dioxide and water in the process called
photosynthesis to produce sugars. Animals can make use of the sugars provided
by the plants in their own cellular energy factories, the mitochondria. These
produce a versatile energy currency in the form of adenosine triphosphate (ATP).
This high-energy molecule stores the energy we need to do just about everything
we do.
Q4. What are the two major life processes that involve both carbon and oxygen?
Answer: Photosynthesis and cellular respiration
Q5. The equation that summarizes the process of cellular respiration.
C6 H12 O6 + 6O2
6 CO2 + 6H2 O
Q6. (a) carbon cycle
(B) A is Cellular respiration, B is Photosynthesis, C is decomposition and D is
sedimentation
Q. What are two major ways that fixes nitrogen in ecosystem?
Ans: Lightening and Nitrogen fixation by nitrogen fixing bacteria called Rhizobium.
Q. Identify the product formed as a result of
(a) Nitrification -----NO2- and NO3(b) N2
Q.9 Explain how weathering releases phosphate from rock—during chemical
weathering, a chemical reaction causes phosphates rocks to break down and
release into soil. E.g. Acid precipitation and lichens releasing chemicals
Physical weathering: process such as wind, rain and freezing release particles of
rock and phosphate into soil.
Q. 10. What is happening in the photograph ?
(A) Clearing of forest by slash and burn method.
(B) This activity release phosphate contained in trees in the form of ash which
accumulates in soil. Then phosphates laches from the ash and run off into the
water supply to settle into the bottom of water bodies such as lakes and oceans
where it becomes unavailable to organisms.
Q11. An example in which carbon moves from the abiotic to the biotic part of the
ecosystem?
Ans. Photosynthsis
Q 12.How do shelled marine organisms contribute to the carbon cycle?
Shells accumulate at the bottom floor when organisms die and form carbonate
rich deposits.
Q.13.Where and in what form does carbon enter long-term stores?
(a).Ans. When dead plants and animals remain trapped in layers of soil or lay at
the bottom of ocean. Also trees falling into swamp water which leads to peat
bogs and finally to coal.
(B). In what form does carbon leave long term reservoir.
Ans. Combustion of fossil fuels and Weathering of sedimentary rocks.
Q.14 How phosphorus circle differs from:
(a) The carbon cycle – Phosphorus cycle differs from carbon cycle because it is not
available in atmosphere reservoir.
(B) Nitrogen: It differs from nitrogen circle because nitrogen becomes available to
living organisms by nitrogen fixation by plants, lightening and fertilizers while
phosphorus becomes available by weathering of rocks. And also phosphorus is
not available in the environment while nitrogen does.
Q. 15 . A food web contains green plants, rabbits, squirrels, mice, seed eating
birds, hawks and owls.
(a) Biomass – most of biomass is available in primary producers because there are
more organisms
(B) The top carnivores will have less biomass because there are very few
organisms
Q16. How bacteria enable plant to take up nitrogen?
Certain species of nitrifying bacteria convert ammonium into nitrite.2) Different
species of nitrifying bacteria convert nitrite into nitrate.
Once nitrates are made available by nitrifying bacteria, nitrates can enter plant
roots and eventually be incorporated into plant proteins.
Q.17
(A) Two largest stores of carbon- Rocks and soils, particularly most of the carbon
locked up in coal and oil deposits and in calcium carbonate based rocks - chalk,
limestone and marble - all of which were living organisms in former times!
Q 18.Why are heavy metals harmful to environment?
Ans. Because they are of high density and are toxic to organisms at low
concentrations. Within the biosphere they do not degrade and can not be
destroyed.
Q. 19.How do PCB’s harm Orcas?
Ans. Because they not only accumulate but concentrate as well. This is because
whales eat more food that has been exposed to PCB’s.
Q 20.Reproductive disorders
Nervous system disorders
Q21. Answer: All energy comes from the sun. Generally, energy is processed
through consumption and break-down, losing a significant percentage of energy
each time.
Nutrients, however, are a little more specific. Nutrient cycles go between living
organisms and the physical environment.
Q.22