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

The change of colour from green to red during ripening of tomatoes and chillies is due to

  1. transformation of chromoplasts into chloroplasts

  2. transformation of chloroplasts into chromoplasts

  3. transformation of chloroplasts into leucoplasts

  4. transformation of leucoplasts into chloroplasts

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is the correct answer because green colour of tomatoes and chillies is due to chloroplast and this chloroplast gets converted into chromoplast.

Multiple choice

In plants, the intensity of the colour or pigmentation depends on the genetics and local environmental conditions of the plants. Which of the following pigments produces the bright autumn colours in plants?

  1. Chlorophylls

  2. Carotenoids

  3. Anthocyanins

  4. Both carotenoids and anthocyanins

  5. Pheophytins
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Bright autumn colours are produced by both photosynthetic yellow pigments (carotenoids) and red pigments (anthocyanins) in leaves.

Multiple choice

Which of the following plants is more efficient in carbon fixation?

  1. Cactus and barley

  2. Sorghum and millet

  3. Wheat and paddy

  4. Potato and pineapple

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

C4 plants like sorghum and millet use PEP carboxylase to concentrate CO2 at RUBISCO, minimizing photorespiration. This makes them more efficient than C3 plants like wheat and paddy.

Multiple choice

The enzyme PEP caboxylase has an advantage over RUBISCO in the fact that

  1. it is present in both mesophyll and bundle sheath cells

  2. it does not promote photorespiration

  3. it requires high concentration of CO2

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

PEP carboxylase has no oxygenase activity, so it does not catalyze photorespiration. Unlike RUBISCO, it exclusively fixes CO2 even in high O2 conditions, making C4 photosynthesis more efficient.

Multiple choice

The enzymes for the biosynthetic reactions or the carbon assimilation are found in the

  1. stroma of chloroplast

  2. stomata of leaf

  3. grana of chloroplast

  4. mitochondrial matrix

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Calvin cycle enzymes are located in the stroma of chloroplasts. This is where carbon fixation and carbohydrate synthesis occur during the dark reactions of photosynthesis. Grana contain chlorophyll for light reactions, while stomata are pores for gas exchange and mitochondria handle cellular respiration.

Multiple choice

The cells which are devoid of chloroplast do not

  1. evolve CO2

  2. utilise carbohydrates

  3. evolve O2

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

Cells without chloroplasts cannot perform photosynthesis or produce oxygen through photosynthetic electron transport. They may still consume oxygen through respiration, require water for metabolic processes, and can utilize carbohydrates obtained from other sources. Only photosynthetic cells containing chloroplasts can evolve oxygen.

Multiple choice

C4 plants differ from C3 plants with reference to the

  1. CO2 acceptor

  2. end product

  3. type of pigments involved

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

C4 plants use phosphoenolpyruvate (PEP) as the primary CO2 acceptor in mesophyll cells, whereas C3 plants use ribulose-1,5-bisphosphate (RuBP) directly in the Calvin cycle. The end products of both pathways are ultimately carbohydrates, and both use similar photosynthetic pigments. The key difference is the initial CO2 fixation mechanism and the spatial separation of carbon fixation in C4 plants.