Tag: botany

Quizzes (264) Questions (5276)

Questions Related to botany

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

Photosynthetic Active Radiation (PAR) has which of the following range of wavelengths?

  1. 400-700 nm

  2. 450-920 nm

  3. 340-450 nm

  4. 500-600 nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The photosynthesis process is essentially a light dependent synthetic process, which results in synthesis of sugars. A small part of the solar spectrum in the visible portion is used in the process of photosynthesis. This small portion of the solar spectrum is called photosynthetically active radiations or PAR. The wavelength of light active in PAR occur between 400 to 700 nm.

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

Which of the following wavelength of light is abosrbed maximum for photosynthesis?

  1. Red light

  2. Blue light

  3. Green light

  4. Yellow light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Blue light of the spectrum is absorbed more for the process of photosynthesis. Plants have two types of chlorophylls - a and b. Chloropphyll a is a specific form of chlorophyll used in oxygenic photosynthesis. It absorbs most energy from wavelengths of violet-blue and orange-red light. A yellow-green chlorophyll pigment which occurs only in plants and green algae. It functions as a light harvesting pigment that pass on the light excitation to chlorophyll a. It absorbs well at wavelength of 450-500 nm and 600-650 nm.

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

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

  1. Violet

  2. Green

  3. Yellow

  4. Red
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chlorophyll absorbs red and violet-blue light, while transmitting and reflecting green light. Chlorophyll 'a' absorbs blue light with wavelengths of 430 nm and red light of 662 nm. 453 nm and 642 nm wavelengths are absorbed by chlorophyll 'b'.

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

Engelmann's experiment with Spirogyra demonstrated that 

  1. The full spectrum of sunlight is needed for photosynthesis

  2. Only red wavelengths are effective in causing photosynthesis

  3. Only Blue wavelengths are effective

  4. Both blue and red wavelengths are effective
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Theodor Wilhelm Engelmann was a German botanist, phsiologist, microbiologist, university professor and musician, whose 1882 experiment measured the effects of different colours of light on photosynthetic activity and showed that the conversion of light energy to chemical energy took place in the chloroplast. Both blue and red wavelength are effective because the amount of oxygen released was found to be maximum in blue and red absorption bands of the chlorophyll.

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

The maximum light absorbed by the chlorophyll a is at the wave length of

  1. 460 nm

  2. 500 nm

  3. 600 nm

  4. 660 nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Small part of visible light in the range of 400 to 700 nm is active in photosynthesis. It is called as photosynthetically active region or PAR. The chlorophyll absorbs maximum in the blue region and red region. The blue region of PAR is near 400 nm after violet and indigo light, while the red region is near 700 nm. The blue region is centered around 460 nm, where chlorophyll a shows maximum absorption.

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

The percentage of light energy utilized for photosynthesis by higher plants is 

  1. 100%

  2. 50%

  3. 10%

  4. 1 to 2%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During photosynthesis 1 to 4% light is utilized. Photosynthesis is more in intense light and is also counted as a limiting factor. Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.

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

Ecological efficiency is

  1. $\frac{Food\ energy\ assimilated}{Food\ energy\ ingested}$ x 100
  2. $\frac{Gross\ primary\ productivity}{Incident\ total\ solar\ radiation}$ x 100
  3. $\frac{Volume\ of\ CO _2\ evolved}{Volume\ of\ O _2\ consumed}$
  4. $\frac{Energy\ in\ biomass\ production\ at\ a\ trophic\ level}{Energy\ in\ biomass\ production\ at\ previous\ trophic\ level}$ x 100
  5. $\frac{Net\ primary\ productivity}{Gross\ primary\ productivity}$ x 100
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An ecological efficiency is the efficiency of energy transfer from one trophic level to the next trophic level. In other words, it is the energy in biomass production at a trophic level divided by energy in biomass production at previous trophic level. It is the ratio of energy flows at different trophic levels in a food-chain. It is expressed in percentage.

Thus, the correct answer is 'Energy in biomass production at a trophic level / Energy in biomass production at previous trophic level x 100.'

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

The wavelength of light most absorbed during photosynthesis is 

  1. 440 nm

  2. 550 nm

  3. 660 nm

  4. 700 nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Wavelength of light absorbed during photosynthesis is 440 nm (violet to blue light). It is the main function of chlorophyll molecule, which is called as the photosynthetic pigment. the violet, blue light have shorter wave length and higher energy content. 

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

Leaves appear green because they

  1. Reflect green light

  2. Absorb green light

  3. Both reflect and absorb green light

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Chlorophyll which is the abundant plant pigment absorbs red and blue light making it photosynthetically efficient. The green wavelengths are reflected giving leaves the green colour. Thus, green is the photosynthetically least efficient wavelength.