Tag: botany

Questions Related to botany

The most effective wavelength of visible light in photosynthesis is in the region

botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. Violet

  2. Blue

  3. Yellow

  4. Red

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Correct Option: D
Explanation:

Plants and other oxygenic photosynthetic organisms harvest light energy from the sun to fix carbon dioxide into the food and fiber required to sustain the biosphere. Since plants cannot move, they must cope with regular day-night cycles, seasonal cycles and neighbouring vegetation, all of which influence the intensity, direction and spectral quality of light impinging on their leaves. 

To optimize light harvesting under low light conditions and to minimize photo damage when light is too bright, plants must continuously adjust the sensitivity of light harvesting by regulating the components of the photosynthetic apparatus or by altering the architecture of their leaves and stems. The ability to sense the ambient light level is conferred by protein light sensors that perceive different colors of visible light that are most effective in photosynthesis. For plants, red light is the most effective wavelength to drive photosynthesis therefore the most important of these photo sensors, the phytochromes, are most sensitive to this region of the light spectrum. Thus, option D is correct.

Flow of energy is unidirectional in an ecosystem because in each trophic level.

botany organisms and their environment energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. Number of consumers is constant

  2. Number of consumers reduces

  3. Loss of energy is more than the amount of available energy

  4. Available energy is completely consumed by consumers

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Correct Option: A

Of the total incident solar radiation the proportion of PAR is 

botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. More than 80%

  2. About 70%

  3. About 60 %

  4. Less than 50 %

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Correct Option: D
Explanation:

Of the total incident solar radiation the proportion of PAR (photosynthetically active radiation) accounts to less than 50%. Photosynthetically active radiation designates the spectral range of solar radiation from 400 to 700 nanometers, that photosynthetic organisms are able to use in the process of photosynthesis.

The pyramid of energy is always upright for any ecosystem. This situation indicates the fact that?

botany ecosystem : structure and function energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. Producers have the lowest energy conversion efficiency

  2. Carnivores have a better energy conversion efficiency than herbivores

  3. Energy conversion efficiency is the same in all trophic levels

  4. Herbivores have a better energy conversion efficiency than carnivores

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Correct Option: A

The percentage of sunlight utilized for photosynthesis by higher plants is 

botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. 100 %

  2. 110 %

  3. 50 %

  4. 1 - 2 %

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Correct Option: D
Explanation:

Higher plants utilize 1 to 2 % of sunlight for photosynthesis. Most crop plants store nearly 0.25% to 0.5% of the sunlight in the product. Examples are corn kernels, potato starch, etc. Photosynthesis increases linearly with light intensity at low intensity, but at higher intensity this is no longer the case.

Emerson defined red drop as decline in the quantum yield of photosynthesis at wavelength of

botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. 460 nm

  2. 670 nm

  3. 680 nm

  4. More than 680 nm

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Correct Option: D
Explanation:

Emerson defined red drop as decline in the quantum yield of photosynthesis  at wavelength beyond 680 nm. 

Red drop effect - Wavelengths beyond 700nm are apparently of insufficient energy to drive any part of photosynthesis. So, a huge drop in efficiency has been noticed at 700nm. In other words there is a sharp decrease in quantum yield at wavelengths greater than 680nm. This decrease in quantum yield takes place in the red part of the spectrum. The number of oxygen molecules released per light quanta absorbed is called as quantum yield of photosynthesis. This effect was first of all noticed by Robert Emerson.

If plant uses $3 \%$ od I.S.R., Then percentage of P.A.R. plant is using

botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. $3 \%$

  2. $6 \%$

  3. $9 \%$

  4. $12 \%$

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Correct Option: A

Which level in food chain has maximum energy?

botany organisms and their environment energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. Third Trophic Level

  2. Decomposers

  3. Herbivores

  4. First Tropic Level

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Correct Option: A

In which layer of atmosphere gases exhibit high kinetic energy?

botany organisms and their environment energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. Troposphere

  2. Stratosphere

  3. Thermosphere

  4. Mesosphere

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Correct Option: C

Photosynthetically active radiation (PAR) represents the following range of wave length

botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

  1. 400-700 nm

  2. 500-600 nm

  3. 450-950 nm

  4. 340-450 nm

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Correct Option: A
Explanation:

Photosynthetically Active Radiation (PAR) is the amount of light available for photosynthesis, which is light in the 400 to 700 nanometer wavelength range. PAR changes seasonally and varies depending on the latitude and time of day.