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BIOLOGY 2 Marks Questions

PART - 2 - Unit IV : CH - 12 Respiration in Plants · Gujarat Board (GSEB) STD 11 Science (GSEB - English Medium). 9 questions.

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Question 22 Marks
What is cellular respiration? Write any four functions of ATP.
Answer
Cellular respiration : When a large amount of energy is released from the cell after the breaking of bonds by oxidation of complex organic molecules, it is called cellular respiration.
Function of ATP : ATP molecules absorb energy which is released in exergonic reactions. These provide energy for various endergonic reactions. Some important activities in which ATP is used are as follows:
(i) In the synthesis of carbohydrates, fats, proteins etc.
(ii) In absorption of organic and inorganic food substances.
(iii) In translocation of organic food substances.
(iv) In protoplasmic streaming.
(v) In growth.
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Question 32 Marks
What do you understand by respiration? Explain Aerobic respiration and Anaerobic respiration.
Answer
$O _2$ is taken in during respiration and $CO _2$ is released and the potential energy stored in organic materials is converted into kinetic energy.
Respiratory equation is as follows :
$C _6 H _{12} O _6+6 O _2 \longrightarrow 6 CO _2+6 H _2 O +686 Kcal$.
Depending on the availability of $O _2$, respiration is of Aerobic and Anaerobic type.
(i) Aerobic respiration : Aerobic respiration occurs in most of the living organisms. This action takes place in the presence of $O _2$. In this, organic substances are completely oxidised to form $CO _2$ and $H _2 O$ and energy is released.
$C _6 H _{12} O _6+6 O _2 \longrightarrow 6 CO _2+6 H _2 O +686 Kcal$.
(ii) Anaerobic respiration : This process occurs in the absence of $O _2$. This process is rarely found in higher class plants but is commonly found in yeast and some bacteria. In this, incomplete oxidation of respiratory substances results in the formation of alcohol or lactic acid and a small amount of energy is released.
$C _6 H _{12} O _6 \longrightarrow 2 C _2 H _5 OH +2 CO _2+50 Kcal$.
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Question 42 Marks
The dry weight of the seed is greater than that of the endosperm grown in darkness, whereas the dry weight of the endosperm with leaves grown in light is greater than that of the seed. Explain the reason.
Answer
Due to lack of photosynthesis in darkness. food substances are used in respiration. Food substances are formed in the presence of light and are also used in respiration. Therefore, dry weight is more.
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Question 52 Marks
Sleeping under a tree at night leads to poor health. Why?
Answer
In plants, respiration occurs both during the day and night, whereas photosynthesis occurs only in sunlight (day). In photosynthesis, CO2 is used and O2 is expelled, whereas in respiration, O2 is used and CO2 is expelled. At night, there is a deficiency of O2 and excess of CO2 under the tree because there is no photosynthesis, hence the use of CO2 is less. A person who sleeps under a tree at night will get less oxygen for respiration and more CO2, hence his health will be poor.
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Question 62 Marks
There are indications of presence of alcohol around the roots in waterlogged rice fields. Give the reason for this.
Answer
O2 is required for the respiration of the roots. Due to water-logging of the soil, before the O2 is present in the water, the roots do aerobic respiration, but as soon as there is a shortage of O2, then anaerobic respiration starts by the roots. And the CO2 released during respiration reacts with the surrounding water and gets converted first into acid and then into alcohol. Due to this, absorption also stops later.
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Question 72 Marks
If dry gram seeds are first adsorbed and then kept in a room with a temperature of $20^{\circ} C$, then what will be the effect on their respiration rate?
Answer
This increases the rate of respiration because water activates the enzymes, keeps the cells turgid and provides a medium for the entry of O2.
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Question 82 Marks
Explain respiratory quotient and oxidative phosphorylation.
Answer
Respiratory Quotient : Generally food items, like carbohydrates, fats etc. are used as respiratory quotient or respiratory medium. Sometimes protein is also used. The respiratory quotient depends upon the type of respiratory substrate used during respiration.
Oxidative Phosphorylation : When a phosphate molecule is attached to ADP, then energy is required for this attachment. In the process of respiration, this energy is obtained from oxidation and based on this energy, when a phosphate molecule is attached to ADP, it becomes ATP. That is, this ATP can be used at any place inside the cell. Therefore, the process of formation of ATP from ADP based on oxidation energy is called oxidative phosphorylation.
$ADP + Pi \xrightarrow[\text { Energy }]{\text { Oxidation }} ATP$
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Question 92 Marks
Fruits and vegetables can be stored for a long time in cold storages. Why does it remain fresh? Explain.
Answer
At very low temperatures the rate of respiration is nil. For this reason, fruits and vegetables can be kept fresh for a long time by keeping them in cold storages.
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