Photosynthesis and Respiration Test - 9

Photosynthesis and respiration are the two vital processes occurring in the plants.  In the given question the two processes that has been discussed are photosynthesis are respiration. During photosynthesis, carbon dioxide is fixed to form glucose and oxygen is released. 

Photosynthesis chemical equation:

6CO₂→12H₂O→C₆H₁₂O₆+6H₂O+6O₂↑

The oxygen from this reaction is fixed for respiration and glucose is broken down for the release of energy. 

Respiration chemical equation:

C₆H₁₂O₆+6O₂→6CO₂+6H₂O+Energy↑

Oxygen released during photosynthesis will be used in respiration.

Thus, the correct answer is 'Photosynthesis and oxygen'.

Sun derives the water cycle; heats up water in ocean and seas, and then water vapours evaporate to air. As the vapours move upward the cool temperature there causes it to condense into clouds and they fall as precipitate like rain, hailstone etc.

Carotenoids are yellow, orange, or red pigments synthesized in roots, stems, leaves, flowers, and fruit of plants. They take part in photosynthesis. They protect plants that are over-exposed to sunlight. They dissipate excess light energy that they absorb as heat. In the absence of carotenoids, this excess light containing UV radiations can destroy proteins, membranes and other plant molecules. Thus, the correct answer is option D.

During photosynthesis, the plants absorb and fix the carbon dioxide from the atmosphere. The carbon dioxide is used by the plant cells to prepare the food in the presence of sunlight and chlorophyll pigment. The carbon dioxide is released as the waste product of respiration by all the living organisms. Carbon dioxide in high amounts is considered as a pollutant. The plants fix this carbon dioxide and reduce the concentration of this gas in the atmosphere and help in the purification of the air.

Thus, the correct answer is option D. 

Light is an important factor needed for photosynthesis. During photosynthesis, the light energy is captured as chemical energy in organic molecules. In cloudy days, the amount of sunlight on the leaves is scanty, so the rate of photosynthesis also decreases.

So, the correct answer is option B.

Phytochrome is a photoreceptor, a pigment that plants, and some bacteria and fungi, use to detect light. It is sensitive to light in the red and far-red region of the visible spectrum. Many flowering plants use it to regulate the time of flowering based on the length of day and night (photoperiodism) and to set circadian rhythms. It also regulates other responses including the germination of seeds, elongation of seedlings, the size, shape, and number of leaves, the synthesis of chlorophyll, and the straightening of the epicotyl or hypocotyl hook of dicot seedlings. 

So, the correct answer is option C.

Earth surface re-emits heat, obtained from the sun, in the form of infrared radiation but part of this does not escape into space as atmospheric gases (e.g., carbon dioxide, methane, etc.) absorb a major fraction of it. The molecules of these gases radiate heat energy,and a major part of which again comes to Earths surface, thus heating it up once again.This cycle is repeated many times. The gases carbon dioxide, methane, chlorofluorocarbons and nitrous oxide  are commonly known as greenhouse gases because they are responsible for the greenhouse effect. The greenhouse effect leads to global warming. Carbon dioxide is also one of the substrates used in the photosynthesis process. An increase in carbon dioxide concentration will increase the rate of photosynthesis. An increase in deserts is called desertification. Desertification will lead to the spread of desert plants. Several factors like a decrease in rainfall, atmospheric pollution, deforestation etc are responsible for the spread of deserts but desertification is not directly linked to increasing carbon dioxide concentration.

So, the correct answer is option D.

The process of water dissociation during photosynthesis is called as photooxidation of water. It requires the presence of Mn⁺⁺, Ca⁺, and Cl⁻, a water oxidizing enzyme etc. It takes place during the light reaction of photosynthesis. So, the correct answer is option A.

Accumulation of auxin as the apex of the plant, which is responsible for the phototropism movement so that plant cells are elongated.

So the correct option is C.

Joseph Priestley discovered oxygen which is used by the plant and animals. He demonstrated that plants liberate oxygen as a product during photosynthesis and that oxygen is utilised by the animals during respiration. Further, plant consumes the carbon dioxide, exhaled by the animals, to carry out photosynthesis. Thus plants and animals restore air for each other.

So the correct answer is 'Plants and animals restore air for each other'.

It is advantageous to use a water plant to demonstrate photosynthesis other than a land plant because O₂ bubbles from cut and can be collected over H₂O. This is due to the fact that, at the end of the photosynthesis, O₂ is released which indicates that, photosynthesis happens. This released O₂ causes O₂ bubbles and plants in the water floats. So, water plants are more advantageous over land plants to demonstrate photosynthesis.

So, the correct answer is option D.

Geotropism (also known as gravitropism) is a turning or growth movement by a plant or fungus in response to gravity. It is a general feature of all higher and many lower plants as well as other organisms. 

Phototropism is the orientation of a plant or other organism in response to light, either toward the source of light (positive phototropism) or away from it (negative phototropism).

A reflex action, differently known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus. Scientific use of the term "reflex" refers to a behavior that is mediated via the reflex arc. 

Spectroscopy is the study of the interaction between matter and electromagnetic radiation. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism. 

So, the correct answer is option A.

Phytochrome is a protein plant pigment which serves to direct the course of plant growth and development. It helps in response related to photoperiodism. It exists in two forms Pr and Pfr. 

So, the correct answer is option A.

Plants require an adequate amount of water, nutrients and sunlight for their proper growth and development.  When plants do not enough sunlight or are grown in areas of darkness, their branches and stems tend to bend towards the source of light. This is one of the tropic movements of plants. Because of this curvature and bending, it appears that plants that grow in darkness are taller.

So, answer B "Taller than those grow in the light" is the correct answer.

Warburg discovered that a decrease in photosynthesis by increasing the oxygen concentration. Oxygen is the competitive inhibitor of the carbon dioxide fixation by RuBisCo, which initiates photosynthesis. Furthermore, oxygen stimulates photorespiration which reduces photosynthetic output. These two mechanisms working together are responsible for the Warburg effect. So, this option is incorrect.

Arnon discovered the photosynthetic phosphorylation. So, this option is incorrect.

Samuel Ruben discovered that oxygen, which is released during photosynthesis, came from a water molecule. So, this option is incorrect.

Emerson observed that when Chlorella cells are exposed to continuous light, the rate of photosynthesis was less as compared to those exposed to the intermittent light. 

So, the correct answer is option B.