Introduction Questions in English

(D) . The whole plant body is enclosed by water. Submerged plants ($e.g.$,$Hydrilla$,$Vallisneria$,$Potamogeton$) do not have stomata because they perform gas exchange directly through their thin epidermal cell walls.

(D) The guard cells are specialized epidermal cells that control the opening and closing of stomata.
These guard cells are surrounded by specialized epidermal cells known as subsidiary cells or accessory cells.
Subsidiary cells provide structural support and assist in the movement of water and ions into and out of the guard cells to regulate stomatal aperture.
Therefore,the correct option is $D$.

(A) Stomata are specialized pores found in the epidermis of leaves and stems that facilitate gas exchange.
Each stoma is surrounded by a pair of specialized kidney-shaped or dumbbell-shaped epidermal cells known as guard cells.
Guard cells regulate the opening and closing of the stomatal pore by changing their turgor pressure.
Other structures like hydathodes,lenticels,and pneumatophores do not possess guard cells.

(B) The term 'Guttation' was coined by the scientist $Burgerstein$ in $1887$.
Guttation is the process of exudation of water droplets from the margins or tips of leaves through specialized structures called hydathodes,typically occurring during early morning or night when root pressure is high and transpiration is low.

(C) In plants,gaseous exchange occurs primarily through specialized pores called $Stomata$.
$Stomata$ are tiny openings found on the epidermis of leaves and young stems.
These pores facilitate the diffusion of $O_2$ and $CO_2$ between the internal tissues of the plant and the external atmosphere.
While $Lenticels$ are involved in gas exchange in woody stems and roots,$Stomata$ are the primary sites for gas exchange in the leaves of annual plants.

(A) Vitamin $D$ is synthesized in the skin when it is exposed to the $UV$ rays of sunlight. The precursor $7$-dehydrocholesterol present in the skin is converted into cholecalciferol (Vitamin $D_3$) upon exposure to $UV$ radiation.

(C) The atmospheric air is composed of various gases.
It contains approximately $78.62\%$ nitrogen $(N_2)$,$20.84\%$ oxygen $(O_2)$,and $0.03\%$ to $0.04\%$ carbon dioxide $(CO_2)$.
Therefore,the standard value for $CO_2$ concentration in the atmosphere is considered to be $0.03\%$.
Thus,option $(c)$ is correct.

(C) The relationship between body size and respiratory rate is inverse. Smaller animals have a higher surface area-to-volume ratio,which leads to a higher metabolic rate per unit of body mass to maintain body temperature and physiological functions. Consequently,smaller animals exhibit a higher respiratory rate compared to larger animals.

(A) The atmospheric air that we inhale contains approximately $21\%$ oxygen $(O_2)$,$78\%$ nitrogen $(N_2)$,and $0.04\%$ carbon dioxide $(CO_2)$.
Therefore,the correct percentage of $O_2$ in inhaled air is $21\%$.

(C) Breathing is a physical process involving the inhalation of atmospheric air and the exhalation of alveolar air (chest movement).
Respiration is a complex biochemical process that involves the oxidation of food materials (glucose) to release energy in the form of $ATP$.
Therefore,statement $C$ is correct because respiration specifically refers to the cellular oxidation of nutrients.

(C) Breathing is a physical process that involves the inhalation of atmospheric air $(O_2)$ and the exhalation of alveolar air $(CO_2)$.
It is often referred to as ventilation.
Respiration is a complex biochemical process that includes breathing,the diffusion of gases across the alveolar membrane,the transport of gases by the blood,and the cellular oxidation of nutrients to produce energy $(ATP)$.
Therefore,breathing is a part of the overall process of respiration.

(D) Cellular respiration is the process by which cells derive energy from glucose.
For aerobic respiration,all animals require $O_2$ as the final electron acceptor in the electron transport chain.
Option $A$ is incorrect because cellular respiration is a metabolic process,not dependent on an external medium.
Option $B$ is incorrect because some small animals (like sponges or cnidarians) rely on simple diffusion and do not have blood for transport.
Option $C$ is incorrect because many organisms (like insects) use tracheal systems,and some use skin (cutaneous respiration) rather than gills or lungs.
Option $D$ is the correct statement as aerobic respiration is a universal requirement for energy production in animals.

(C) The normal respiratory rate (breathing rate) for a healthy adult at rest is typically between $12$ and $16$ breaths per minute. This rate allows for the efficient exchange of oxygen and carbon dioxide in the lungs to maintain homeostasis.

(B) The correct answer is $B$. Tears contain an enzyme called $Lysozyme$. This enzyme acts as an antibacterial agent by breaking down the cell walls of bacteria,thereby preventing eye infections. It can dissolve many saprophytes rapidly and completely,and along with other agents,it inhibits the growth of various pathogenic bacteria.

(A) Hibernation is a state of minimal metabolic activity in some animals to survive harsh winter conditions.
During true hibernation,the body temperature of warm-blooded animals (endotherms) drops significantly to match the ambient temperature of the surroundings.
This allows the animal to conserve energy by reducing the metabolic rate to a very low level.
Therefore,the body temperature becomes approximately the same as that of the surroundings.

(C) Vitamin $D$ is synthesized in the human body when the skin is exposed to ultraviolet $(UV)$ radiation from sunlight.
Specifically,$7$-dehydrocholesterol present in the skin cells is converted into cholecalciferol (Vitamin $D_3$) upon exposure to $UV$ rays.
Therefore,the skin is the primary site for the synthesis of Vitamin $D$ in humans.

(C) Respiration involves both physical and chemical components.
$1$. The physical component involves the exchange of gases ($O_2$ and $CO_2$) between the atmosphere and the blood,and between blood and tissues (breathing).
$2$. The chemical component involves the oxidation of food (glucose) within the cells to release energy in the form of $ATP$.
Therefore,it is considered a physico-chemical process.

(C) The eggshell of a bird is porous,allowing for the exchange of gases ($O_2$ and $CO_2$) between the developing embryo and the external environment.
When the egg is coated with varnish,these pores are blocked.
As a result,the developing embryo cannot obtain the necessary $O_2$ for respiration and cannot eliminate the $CO_2$ produced.
Consequently,the embryo dies due to suffocation caused by the lack of $O_2$ and the inability to perform gas exchange.

(C) Guard cells are specialized epidermal cells that surround the stomatal pore.
Unlike typical epidermal cells,which are generally transparent and lack chloroplasts,guard cells contain chloroplasts.
These chloroplasts are responsible for photosynthesis,which helps in regulating the opening and closing of stomata by changing the turgor pressure within the guard cells.

(D) The normal human body temperature is $37\,^{\circ}C$.
To convert temperature from Celsius to Kelvin,we use the formula: $T(K) = T(^{\circ}C) + 273.15$.
Using the standard approximation of $273$,the calculation is: $37 + 273 = 310\,K$.
Therefore,the normal body temperature on the Kelvin scale is $310\,K$.

(C) Plants require $O_{2}$ for respiration and release $CO_{2}$ as a byproduct.
Unlike animals,plants do not possess specialized respiratory organs for gaseous exchange.
Instead,they utilize structures such as stomata (in leaves) and lenticels (in stems) to facilitate the exchange of gases with the environment.

(A) $(1)$ Each plant part takes care of its own gas-exchange needs.
$(2)$ There is very little transport of gases from one plant part to another.
$(3)$ Plants do not present great demands for gas exchange.
$(4)$ Roots,stems,and leaves respire at rates far lower than animals do.
$(5)$ Only during photosynthesis are large volumes of gases exchanged,and each leaf is well adapted to take care of its own needs during these periods. When cells photosynthesize,the availability of $O_{2}$ is not a problem in these cells since $O_{2}$ is released within the cells.
$(6)$ The distance that gases must diffuse,even in large,bulky plants,is not great.

(N/A) Breathing is the process of exchanging $O_{2}$ from the atmosphere with $CO_{2}$ produced by the cells. It is commonly known as ventilation.

(N/A)

Respiration	Cellular Respiration
$(1)$ It is a physical process.	$(1)$ It is a biochemical process.
$(2)$ It occurs in the respiratory tract/organs.	$(2)$ It occurs in the cytoplasm and mitochondria of the cell.
$(3)$ It involves the exchange of $O_2$ and $CO_2$ between the body and the environment.	$(3)$ It involves the oxidation of glucose to release energy in the form of $ATP$.
$(4)$ Inspiration and expiration are mechanical processes.	$(4)$ It is a metabolic process involving enzymatic reactions.

(N/A) $(1)$ Cellular respiration: It is a catabolic process in which energy is released through the oxidation of glucose,and $CO_2$ is produced as a byproduct.
$(2)$ Respiratory system: The structural organization comprising the transport route and organs where the exchange of $O_2$ and $CO_2$ occurs between the atmosphere and the blood is called the respiratory system.

(N/A)

Internal Respiration	External (Surfacial) Respiration
$(1)$ It occurs inside the cell.	$(1)$ It occurs at the respiratory surface.
$(2)$ Exchange of respiratory gases does not occur here.	$(2)$ Exchange of respiratory gases occurs between the atmosphere and blood.
$(3)$ Energy is released in the form of $ATP$.	$(3)$ Energy is not released.
$(4)$ It is a complex biochemical process.	$(4)$ It is a physical process based on the law of partial pressure of gases.

(N/A) $1$. Plants can manage excess water by increasing the rate of transpiration up to a certain limit to remove surplus water.
$2$. In flooded conditions,some plants develop specialized structures like aerenchyma (spongy tissue with air spaces) to facilitate gas exchange in submerged roots.
$3$. Some plants also possess adventitious roots that grow near the surface to obtain oxygen.
$4$. If the plant roots remain submerged in water for an extended period,the lack of oxygen (anoxia) leads to root decay and eventually the death of the plant.

(A) Each stoma (plural: stomata) is surrounded by two specialized,green,kidney-shaped epidermal cells known as guard cells,which regulate the opening and closing of the stomatal pore based on turgor pressure changes.
Adjacent to the guard cells,there are usually one or more modified epidermal cells referred to as accessory or subsidiary cells.
Epidermal cells form the outer layer of the leaf and are directly associated with the stomatal complex.
Sclerenchymatous cells are thick-walled,lignified,dead cells that provide mechanical support to the plant body.
Therefore,sclerenchymatous cells are not involved in the structure or function of stomata.

(C) The Assertion is incorrect because stomata are primarily involved in gas exchange and transpiration,not in the direct production of food (which is the role of chloroplasts in mesophyll cells). While they regulate water loss (preventing thirst/desiccation),they do not 'provide food'.
The Reason is correct because stomata are specialized pores primarily designed for the exchange of gases like $CO_2$ and $O_2$ between the plant and the atmosphere.
Therefore,the Assertion is incorrect,but the Reason is correct.

(C) Plants do not require specialized respiratory organs for several reasons:
$1$. Each plant part takes care of its own gas-exchange needs. Roots,stems,and leaves respire at rates far lower than animals.
$2$. Plants do not have great demands for gas exchange. Unlike animals,plants do not show massive gas exchange requirements at the whole-organism level.
$3$. During photosynthesis,large volumes of gases are exchanged,but each leaf is well-adapted to take care of its own needs through stomata.
$4$. The distance that gases must diffuse in plants is not great,as most living cells are located near the surface.

(C) According to the $NCERT$ textbook, the process of exchange of $O_{2}$ from the atmosphere with $CO_{2}$ produced by the cells is called breathing, which is commonly known as respiration.
Therefore, $A = CO_{2}$, $B = \text{breathing}$, and $C = \text{respiration}$.
Thus, the correct option is $C$.

(A) Inhaled air is the atmospheric air that we breathe in. Atmospheric air contains approximately $21 \%$ oxygen,$78-79 \%$ nitrogen,and $0.03 \%$ carbon dioxide.

(A) When we perform physical exercise,the body requires more energy to support the increased rate of muscular contraction and metabolic activity. Therefore,the energy demand is increased.

(A) The correct statements are $A$ and $C$.
Statement $A$ is correct: Terrestrial plants possess intercellular air spaces in leaves and roots to facilitate gas diffusion.
Statement $B$ is incorrect: Woody trees have lenticels,not stomata,on their bark.
Statement $C$ is correct: In aerated soil,oxygen dissolved in the thin film of water surrounding soil particles enters root hairs by diffusion.
Statement $D$ is incorrect: Vascular bundles are for transport,not gas exchange.
Statement $E$ is incorrect: Gases diffuse out of lenticels,not into them,as part of respiration.