GK Quiz on Photosynthesis: 20 Important Questions with Answers

Photosynthesis is one of the most important processes on Earth. It is the method by which green plants, algae, and some bacteria prepare their own food using sunlight, water, and carbon dioxide. This process not only feeds the plants but also produces the oxygen that all living beings breathe. If you are a student looking to test your science knowledge, this photosynthesis quiz is the perfect place to start. Try answering these questions and see how well you know this fascinating topic.

GK Quiz on Photosynthesis

Question 1: What is the primary source of energy for photosynthesis?

Answer: Sunlight

Sunlight is the main energy source that drives the process of photosynthesis. Plants absorb this light energy through a pigment called chlorophyll, which is found in their leaves.

Question 2: Which gas do plants absorb from the atmosphere during photosynthesis?

Answer: Carbon Dioxide (CO2)

Plants take in carbon dioxide through tiny pores on their leaves called stomata. This gas is one of the two main raw materials needed to carry out photosynthesis.

Question 3: What is the green pigment in plants that absorbs sunlight called?

Answer: Chlorophyll

Chlorophyll is the pigment responsible for the green colour of leaves. It captures light energy from the sun and uses it to power the photosynthesis process.

Question 4: Where in the plant cell does photosynthesis take place?

Answer: Chloroplast

Chloroplasts are specialised structures found inside plant cells. They contain chlorophyll and are the site where the entire process of photosynthesis occurs.

Question 5: What is the food that plants produce during photosynthesis?

Answer: Glucose

Through photosynthesis, plants convert carbon dioxide and water into glucose, a type of simple sugar. This glucose serves as the energy source for the plant's growth and functions.

Question 6: Which gas is released by plants as a byproduct of photosynthesis?

Answer: Oxygen

Oxygen is released into the atmosphere as a byproduct when plants split water molecules during photosynthesis. This is the oxygen that humans and animals breathe.

Question 7: What is the other raw material required for photosynthesis besides carbon dioxide?

Answer: Water

Water is absorbed by the roots of the plant and transported to the leaves. Along with carbon dioxide, it is one of the two essential ingredients needed for photosynthesis to occur.

Question 8: Through which part of the leaf do plants take in carbon dioxide and release oxygen?

Answer: Stomata

Stomata are tiny pores found mostly on the underside of leaves. They allow the exchange of gases between the plant and the surrounding air.

Question 9: Which part of the plant is considered the main site of photosynthesis?

Answer: Leaves

Leaves are the primary organs where photosynthesis takes place. Their flat, broad shape allows them to absorb maximum sunlight, and they contain the highest concentration of chlorophyll.

Question 10: What is the chemical formula of glucose produced during photosynthesis?

Answer: C6H12O6

Glucose is a simple sugar made up of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms. It is the direct product of photosynthesis and the main energy molecule for the plant.

Question 11: What happens to photosynthesis at night?

Answer: It stops

Photosynthesis requires sunlight to occur. Since sunlight is absent at night, the process comes to a halt. However, plants continue to carry out respiration during the night.

Question 12: Which colour of light is most effective for photosynthesis?

Answer: Red and Blue light

Chlorophyll absorbs red and blue wavelengths of light most efficiently. Green light is mostly reflected, which is why leaves appear green to our eyes.

Question 13: What is the overall chemical equation for photosynthesis?

Answer: 6CO2 + 6H2O + Light Energy = C6H12O6 + 6O2

This equation shows that six molecules of carbon dioxide and six molecules of water, in the presence of light energy, produce one molecule of glucose and six molecules of oxygen.

Question 14: Which organisms other than plants can also perform photosynthesis?

Answer: Algae and Cyanobacteria

Algae are found in water bodies and also contain chlorophyll. Cyanobacteria, also called blue-green algae, are among the earliest organisms on Earth known to carry out photosynthesis.

Question 15: What is the role of water in photosynthesis?

Answer: Water is split to release oxygen and provide hydrogen

During the light reactions of photosynthesis, water molecules are broken apart. This splitting releases oxygen as a byproduct and provides hydrogen atoms that help form glucose.

Question 16: What do we call organisms that can make their own food through photosynthesis?

Answer: Autotrophs

Autotrophs are self-feeding organisms. Plants, algae, and certain bacteria are autotrophs because they produce their own food using sunlight, water, and carbon dioxide without depending on other organisms.

Question 17: Which part of the plant absorbs water for photosynthesis?

Answer: Roots

Roots absorb water from the soil and send it upward through a network of vessels to the leaves. This water reaches the chloroplasts where it is used in the process of photosynthesis. 

Question 18: What is the name of the tiny openings on leaves that help in the exchange of gases?

Answer: Stomata (singular: Stoma)

Stomata act as gateways for gas exchange in plants. They open during the day to allow carbon dioxide in and oxygen out, and often close at night to prevent excess water loss.

Question 19: Why do plants appear green?

Answer: Because chlorophyll reflects green light

Chlorophyll absorbs red and blue light for photosynthesis but reflects green light back. This reflected green light is what reaches our eyes, making the plant appear green.

Question 20: What is the importance of photosynthesis for life on Earth?

Answer: It produces oxygen and forms the base of the food chain

Photosynthesis is the foundation of almost all life on Earth. It releases oxygen that living beings breathe and produces glucose that directly or indirectly serves as food for nearly all organisms on the planet.