Biology

Photosynthesis in Plants

1,492 Questions

Photosynthesis is the biological process by which plants convert light energy into chemical energy. This page contains practice questions covering essential topics like chlorophyll, light reactions, and the pathways specific to plants. This material is crucial for medical entrance exams and academic assessments.

Chlorophyll and pigmentsLight reactionsCalvin cycleCAM plantsElectron transportPhotosynthesis factors

Photosynthesis in Plants Questions

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

According to Sachs, photosynthesis takes place at the

  1. Minimum value.

  2. Maximum value.

  3. Optimum value.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Blackman's Law of limiting factors are the various factors which affect the rate of photosynthesis. It is considered that when the other factors are constant, the factor which is least or minimum has the direct effect on the rate of photosynthesis. Sachs developed three cardinal points for each factor which affects the rate of photosynthesis. These cardinals have minimum, optimum and maximum values. The process of photosynthesis starts at the minimum and takes place at the optimum value. the rate of photosynthesis is much smaller at the maximum value and stops above this point.

Thus, the correct answer is option C. 

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

A plant is exposed to an optimum amount of light intensity, with a limited supply of CO$ _2$. As the carbon dioxide, concentration increases the rate of photosynthesis increases. Which of the following act as limiting factor in above-given case?

  1. Carbon dioxide

  2. Light

  3. Temperature

  4. Both A and B
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Blackman's law of limiting factors are the various factors which affect the rate of photosynthesis. It is considered that when the other factors are constant, the factor which is least or minimum has the direct effect on the rate of photosynthesis. When the light intensity is maintained at the optimum level, the other factor which is CO$ _2$ supply is reduced. This causes the rate of reaction to completely depend on CO$ _2$. When the carbon dioxide concentration increases, the rate of reaction increases. This explains that the limiting factor is carbon dioxide. 
Thus, the correct answer is option A. 
Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

A plant is exposed to an optimum amount of carbon dioxide, with a limited light intensity. As the intensity of light increases, the rate of photosynthesis increases. Which of the following act as limiting factor in above-given case?

  1. Light

  2. Carbon dioxide

  3. Temperature

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Blackman's law is applicable to photosynthesis. It states that a process  is controlled by many factors but the rate of photosynthesis will depend on the factor which is present in limited quantity. If all factors are present but light intensity is low then light will become the limiting factor and rate of photosynthesis will depend only on light, the limiting factor. The level of carbon dioxide is maintained constant and so light is the limiting factor. 
Thus, the correct answer is option A.
Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

At high temperatures, the enzymes of photosynthesis gets deactivated because 

  1. They get denatured.

  2. They are proteinous in nature.

  3. They have optimum range of temperature at which they are functional.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are biological catalysts which can normally function at body temperatures. There are various different enzymes involved in the process of photosynthesis. The enzymes have optimum temperature range. This is the range in which they show maximum activity. The enzymes are proteins which gets denatured at higher temperature. The structure of these enzymes gets modified and the active sites are destroyed. This results in the inactivation of the enzymes. 

Thus, the correct answer is option D. 

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

Which one of the following is limiting rate of photosynthesis in nature

  1. Light
  2. $CO _2$
  3. $O _2$

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

Carbon dioxide is a major limiting factor influencing the rate of photosynthesis. The concentration of $CO _{2}$ is very low in the atmosphere (between 0.03 percent and 0.04 percent). This level of carbon dioxide is far below the requirement for optimum photosynthesis. Increase in concentration up to 0.05 percent can cause an increase in the rate of photosynthesis but beyond this level, it becomes damaging over longer periods.

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

Which one of the following would not be limiting factor in photosynthesis?

  1. $O _2$
  2. $CO _2$

  3. Chlorophyll

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

Photosynthesis is the process in which sunlight is used to form carbohydrate mainly glucose by reduction of carbon dioxide and oxidation of water.

Factors that affect photosynthesis are:-
  1. Light.
  2. Temperature. 
  3. Carbon dioxide concentration.
  4. Water
oxygen does not play any role as it is released as the waste product after splitting of water.
So the correct option is 'O$ _2$'

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

Which part of the photosynthetic process does not require light and temperature?

  1. Hill's reaction

  2. Blackman's reaction

  3. Warburg's reaction

  4. Emerson's reaction
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The process of carbon assimilation occurs in light independent way. It is called as a dark reaction. Since, Blackman demonstrated the existence of dark reaction, the reaction is also called as Blackman’s reaction.

Thus, the correct answer is option B.

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

Blackman demonstrated that increasing illumination increased the photosynthetic rate upto a point when $CO _{2}$ become limiting. If light was not limiting, temperature become limiting. Emerson found that maximum $CO _{2}$ fixation could be achieved with brief flashes of light. Choose the correct statement from the following.

  1. Only one factor can be limited in photosynthesis.

  2. Photosynthesis consists of a light and dark reaction.

  3. The trapping of light by chloroplast is temperature dependent.
  4. The trapping of light by chloroplast can occur if $CO _{2}$ is present.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Blackman proposed the law of limiting factors in 1905. According to this law, when a process depends on a number of factors, its rate is limited by the pace of the slowest factor. Blackman's law of limiting factors determines the rate of photosynthesis. Emerson found that maximum $CO _2$ fixation could be achieved with brief flashes of light. From both observations we can say that only one factor can be limiting in photosynthesis at a time. 

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

The law of limiting factors for photosynthesis was enunciated by

  1. R. Hill

  2. Calvin

  3. Krebs

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

In the year 1905, Blackman proposed the law of limiting factors for photosynthesis. According to this law the process totally depends upon the light factors and its rate is limited by the pace of the slowest factor. This law of limiting factor determines the rate of the photosynthesis.

so the correct option is D.

Multiple choice biology plant nutrition limiting factors factors affecting photosynthesis photosynthesis in higher plants

Choose the correct answer from the alternatives given.
The rate of photosynthesis declines in the presence of 

  1. Green light

  2. blue light

  3. orange light

  4. far red light
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The wavelength of light is also important in the process of photosynthesis. As we know that the  PSI absorbs energy most efficiently at 700 nm and PSII at 680 nm. Light with a higher proportion of the energy of different wavelengths will produce a different rate of photosynthesis i.e the more the wavelength the effective photosynthesis occur. Certain red and blue wavelengths of light are the most effective in photosynthesis because they have exactly the right amount of energy to energize, or excite, chlorophyll electrons. Greenlight is considered the least efficient wavelength in the visible spectrum for photosynthesis, but it is still useful in photosynthesis.
So the correct option is 'Green light'.
Multiple choice factors affecting respiration living organisms and energy production life processes in living organisms- part 1 respiration biology

Which of the following is necessary for respiration in plants?

  1. Carbon dioxide

  2. Oxygen

  3. Chlorophyll

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

Oxygen is the final electron electron acceptor in the electron transport chain, which occurs in the mitochondria. So, for aerobic respiration oxygen is must. Respiration decreases with decreased available oxygen. Under circumstances where no oxygen is present, like in poorly draining soil, anaerobic respiration (fermentation) occurs.

Multiple choice botany photosynthesis action spectrum and absorption spectrum spectrum of electromagnetic radiation chloroplast and pigments of photosynthesis

If the oxygen of $CO _2$ is radiolabelled and provided to the plant, then which of the following will show radioactivity in the cells exposed to sunlight?

  1. Hexose
  2. $H _2O$
  3. $O _2$

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

In photosynthesis, the carbon from CO2 is incorporated into glucose (a hexose sugar). If the carbon in CO2 is radiolabeled, the resulting hexose will show radioactivity.

Multiple choice biology micro - organism useful actions of algae introduction to algae algae

Alga that is useful for prolonged space flight for liberation of oxygen, consumption of $C{O} _{2}$, disposal of wastes and formation of food is

  1. Ulva

  2. Caulerpa

  3. Chlorella

  4. Chlamydomonas
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chlorella is widely known in biological studies for its efficiency in photosynthesis, making it a candidate for oxygen regeneration and food production in closed environments like space crafts.

Multiple choice botany mineral nutrition in plants deficiency diseases and symptoms deficiency symptoms macronutrients and micronutrients

While in N, K and Mg deficiency, chlorosis appears first in _____ leaves; in S and Ca deficiency,_____ leaves are the first to be affected.

  1. Young, old

  2. Old, young

  3. Old, old

  4. Young, young
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Elements like N, K, and Mg are mobile in plants, so they are transported to young leaves when deficient, causing symptoms to appear first in old leaves. S and Ca are relatively immobile, so deficiency symptoms appear first in young leaves.