Nutrition Questions in English

(N/A) The human alimentary canal is a continuous tube extending from the mouth to the anus. It consists of several organs that work together to digest food and absorb nutrients.
$1$. Mouth (Buccal cavity): The starting point of the alimentary canal where ingestion occurs and mechanical digestion begins with the help of teeth and saliva.
$2$. Oesophagus: $A$ muscular tube that carries food from the mouth to the stomach through peristaltic movements.
$3$. Stomach: $A$ $J$-shaped muscular organ that stores food and mixes it with gastric juices for chemical digestion.
$4$. Intestine: Divided into the small intestine (where major digestion and absorption of nutrients take place) and the large intestine (where water is absorbed and waste is prepared for excretion).
Refer to the provided diagram for the anatomical positions of these parts.

(N/A) The digestion of food in humans occurs in the following stages:
$1$. Carbohydrates: Digestion begins in the mouth where salivary amylase breaks down starch into simpler sugars. It continues in the small intestine,where pancreatic amylase converts remaining carbohydrates into glucose.
$2$. Proteins: Digestion begins in the stomach with the action of pepsin in an acidic medium. It is completed in the small intestine by pancreatic enzymes like trypsin and chymotrypsin,which break proteins down into amino acids.
$3$. Fats: Digestion occurs primarily in the small intestine. Bile salts emulsify large fat globules into smaller droplets,and then the enzyme lipase breaks them down into fatty acids and glycerol.

(N/A) The mechanism of photosynthesis involves the following three main steps:
$1$. Absorption of light energy by chlorophyll: The green pigment chlorophyll present in the chloroplasts of plant cells absorbs solar energy.
$2$. Conversion of light energy into chemical energy: The absorbed light energy is used to split water molecules $(H_2O)$ into hydrogen and oxygen. This process is known as photolysis. Chemical energy is stored in the form of $ATP$ and $NADPH$.
$3$. Reduction of $CO_2$ into carbohydrates: The chemical energy generated is used to reduce carbon dioxide $(CO_2)$ into glucose $(C_6H_{12}O_6)$,which serves as the primary food source for the plant.

(B) Heterotrophic organisms,commonly known as heterotrophs,are those that cannot synthesize their own food. They utilize complex organic substances obtained from other organisms and break them down into simpler forms using enzymes to derive energy. Examples include animals,fungi,and most bacteria.

(C) Roughage,also known as dietary fiber,is the component of food that is not digested in the human stomach. It consists mainly of cellulose,a complex carbohydrate found in plant cell walls,which human digestive enzymes cannot break down. It passes through the digestive tract and helps in the movement of food and waste.

(A) The reserved food material in plant cells is $Starch$. Plants synthesize glucose during photosynthesis and store the excess glucose in the form of $Starch$ for later use.

(B) In animals,carbohydrates are stored in the form of $Glycogen$. This is often referred to as animal starch and is primarily stored in the liver and muscle cells to be used as an energy reserve.

(C) The absorption of water and certain salts from the undigested food material occurs in the large intestine. After the absorption of water,the remaining waste material is solidified and eliminated from the body through the anus.

(C) Tapeworms exhibit $Parasitic$ nutrition. They live inside the body of the host (such as humans) and derive their nutrients directly from the host's digested food, which is a form of heterotrophic nutrition.

(N/A) Holozoic nutrition is a type of heterotrophic nutrition in which an organism ingests complex organic food materials,either solid or liquid. This food is then broken down into simpler,absorbable forms through the process of digestion. After digestion,the nutrients are absorbed into the body cells and assimilated. Examples include $Amoeba$,humans,and frogs.

(A) Bile,secreted by the liver and stored in the gallbladder,plays a crucial role in the digestion of fats.
It contains bile salts that break down large fat globules into smaller droplets,a process known as emulsification.
This increases the surface area of the fats,allowing enzymes like lipase to act more efficiently on them.

(N/A) $(i)$ Autotrophs obtain $CO_{2}$ from the atmosphere through the diffusion process via stomata present on the surface of leaves.
$(ii)$ Autotrophs obtain nitrogen $(N_{2})$ from the soil in the form of inorganic nitrates and nitrites,which are absorbed by the roots along with water.

(B) The digestion of fat primarily takes place in the $Small \ intestine$.
First, bile salts from the liver emulsify large fat globules into smaller droplets to increase the surface area for enzyme action.
Then, the enzyme $Lipase$ (secreted by the pancreas) breaks down these emulsified fats into fatty acids and glycerol.

(B) Photosynthesis is the process by which green plants synthesize their food. This process takes place in specialized cell organelles known as chloroplasts. Chloroplasts contain the green pigment chlorophyll,which captures light energy to convert carbon dioxide and water into glucose.

(B) The raw materials required for photosynthesis are:
$(i)$ $CO_{2}$ (Carbon dioxide): Taken from the atmosphere through stomata.
$(ii)$ $H_{2}O$ (Water): Absorbed from the soil by the roots.
These substances,along with sunlight and chlorophyll,are used by plants to synthesize glucose.

(N/A) The protein-digesting enzyme present in pancreatic juice is $Trypsin$. The hormone secreted by the pancreas is $Insulin$.
$(b)$ Pancreatic juice contains enzymes like $Trypsin$ for protein digestion,$Lipase$ for fat digestion,and $Amylase$ for carbohydrate digestion. It also contains bicarbonate ions that neutralize the acidic chyme coming from the stomach,creating an alkaline environment necessary for the action of these enzymes.

(N/A) $(i)$ Gastric glands: These are present in the walls of the stomach. They secrete $HCl$,a protein-digesting enzyme called pepsin,and mucus.
$(ii)$ Pancreas: This gland secretes pancreatic juice,which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.

(A) During the process of digestion, complex food molecules are broken down into simpler, absorbable forms.
$1$. Carbohydrates are broken down into simple sugars, primarily $Glucose$.
$2$. Proteins are broken down into their basic building blocks, known as $Amino acids$.
$3$. Fats are broken down into $Fatty acids$ and $Glycerol$.

(B) Desert plants are adapted to arid environments where they keep their stomata closed during the day to prevent water loss through transpiration.
To perform photosynthesis,they take up $CO_2$ at night and convert it into an intermediate organic acid (like malic acid).
During the daytime,the energy absorbed by the chlorophyll from sunlight is used to process this stored intermediate molecule into glucose,allowing photosynthesis to occur without opening the stomata.

(N/A) $1$. Salivary amylase: It is secreted by salivary glands and breaks down starch into simpler sugars like maltose.
$2$. Pepsin: It is secreted by the gastric glands in the stomach and helps in the digestion of proteins into peptides/amino acids.
$3$. Trypsin: It is secreted by the pancreas and helps in the digestion of proteins in the small intestine.
$4$. Lipase: It is secreted by the pancreas and breaks down emulsified fats into fatty acids and glycerol.

(N/A) Plants store carbohydrates in the form of $Starch$,which serves as their internal energy reserve.
No,animals do not have the same energy reserve. Animals store carbohydrates in the form of $Glycogen$ as their internal energy reserve.

(N/A) Salivary amylase acts on starch present in the food within the buccal cavity.
It breaks down complex starch molecules into simpler sugars,specifically maltose,which is the initial product of this enzymatic action.

(D) The direction of diffusion in plants is primarily determined by the following factors:
$1$. Concentration gradient: Molecules move from a region of higher concentration to a region of lower concentration.
$2$. Permeability of the membrane: The selective nature of the cell membrane regulates the movement of substances.
$3$. Environmental conditions: Factors like temperature and pressure significantly influence the rate and direction of diffusion.
$4$. Requirement of the plant: The metabolic needs of the plant cells dictate the uptake or release of specific substances.
Therefore,all these factors collectively maintain the direction of diffusion.

(B) $I$ would suggest a meat-based diet for the bear.
Reasoning: Herbivores,which consume plant-based diets,require a longer small intestine to allow sufficient time for the digestion of cellulose. Since a significant portion of the bear's small intestine has been removed,its ability to digest complex plant matter is compromised. Meat is easier and faster to digest compared to plant material,making it a more suitable diet for an animal with a shortened digestive tract.

(N/A) $1$. Gaseous exchange: Stomata facilitate the exchange of gases like $CO_2$ and $O_2$ between the atmosphere and the internal tissues of the leaf,which is essential for photosynthesis and respiration.
$2$. Transpiration: Stomata allow for the loss of water in the form of water vapor from the aerial parts of the plant,a process known as transpiration,which helps in the upward movement of water and minerals from the roots.

(N/A) The food coming from the stomach is acidic in nature. Bile juice makes this food alkaline so that pancreatic enzymes can act upon it.
Bile salts present in the bile juice break down large fat globules into smaller globules,a process known as emulsification.
This increases the surface area of the fat,thereby significantly increasing the efficiency of lipase enzyme action.

(N/A) Paramecium is a unicellular organism that follows holozoic nutrition.
It possesses a specific region known as the cytostome or oral groove for food ingestion.
The entire surface of the Paramecium is covered with hair-like structures called cilia.
These cilia beat in a coordinated rhythmic motion,creating water currents that sweep food particles (like bacteria) towards the oral groove.
Once the food enters the oral groove,it is engulfed into a food vacuole,where digestion occurs.

(N/A) The saliva present in the mouth contains an enzyme called salivary amylase,which breaks down the starch present in the bread into simple sugars. This is why a piece of bread tastes sweet when chewed for some time.
$(b)$ Cellulose is a complex carbohydrate that requires specific enzymes and a longer time for digestion. Herbivorous animals like cows possess a specialized stomach (rumen) and a longer small intestine,which allow for the fermentation and digestion of cellulose by symbiotic bacteria. In contrast,human beings lack the necessary enzymes and the specialized digestive tract to break down cellulose. Therefore,it remains undigested in humans and acts as roughage,which helps in bowel movement.

(N/A) Mucus protects the inner lining of the stomach from the action of the acid under normal conditions.
$(b)$ The exit of food from the stomach is regulated by sphincter muscles,which release it in small amounts into the small intestine.
$(c)$ From the stomach,food enters the small intestine.

(N/A) The food coming from the stomach is acidic in nature due to the presence of $HCl$.
$(b)$ $(i)$ The inner lining of the small intestine has numerous finger-like projections called villi,which significantly increase the surface area for the absorption of digested food.
$(ii)$ The small intestine is a long,highly coiled tube,which ensures that the food stays in the intestine for a longer duration,allowing for maximum absorption of nutrients.

(N/A) The extensively coiled structure of the alimentary canal is the small intestine.
$(b)$ The length of the small intestine varies in different animals depending on the type of food they consume. Herbivores,which feed on grass,require a longer small intestine to facilitate the digestion of cellulose. In contrast,carnivores possess a shorter small intestine because meat is comparatively easier to digest.

(N/A) The chemical equation for photosynthesis is: $6CO_2 + 6H_2O \xrightarrow[\text{Chlorophyll}]{\text{Sunlight}} C_6H_{12}O_6 + 6O_2$.
The three main events that occur during photosynthesis are:
$(i)$ Absorption of light energy by chlorophyll.
$(ii)$ Conversion of light energy into chemical energy and the splitting of water molecules into hydrogen and oxygen.
$(iii)$ Reduction of $CO_2$ into carbohydrates.
In desert plants,the process is adapted to conserve water. They take up $CO_2$ at night and prepare an intermediate product. During the day,when chlorophyll absorbs sunlight,this energy is used to act upon the intermediate product to synthesize carbohydrates.

(A) The glands associated with the digestion of starch are:
$1$. Salivary glands: Secrete salivary amylase,which breaks down starch into simpler sugars in the mouth.
$2$. Pancreas: Secretes pancreatic amylase,which digests starch in the small intestine.
$3$. Intestinal glands: Secrete intestinal amylase,which completes the digestion of starch into glucose.
Maintenance of $pH$:
- In the stomach: The gastric glands secrete Hydrochloric acid $(HCl)$,which creates an acidic medium (low $pH$) necessary for the activation of the enzyme pepsin.
- In the small intestine: The acidic food coming from the stomach is made alkaline by bile juice (from the liver) and pancreatic juice (from the pancreas),which is necessary for the action of pancreatic enzymes.

(N/A) $(i)$ Liver.
$(ii)$ Pancreas.
$(iii)$ Small intestine.
$(b)$ Villi are numerous finger-like projections present in the inner lining of the small intestine.
Function: They increase the surface area for the absorption of digested food.

(N/A) The digestive system in humans is associated with several glands that produce secretions essential for digestion. Three such glands and their secretions are as follows:

Name of the gland	Secretions produced
Salivary glands	Saliva (contains salivary amylase/ptyalin)
Gastric glands	$HCl$, mucus, and pepsin
Liver	Bile juice
Pancreas	Pancreatic juice (contains trypsin, lipase, and amylase)
Intestinal glands	Intestinal juice

(N/A) $(i)$ Gall bladder
$(ii)$ Liver
$(b)$ Pancreatic juice contains several enzymes. One such enzyme is Trypsin,which digests proteins into amino acids. Another is Lipase,which breaks down emulsified fats into fatty acids and glycerol.
$(c)$ Peristaltic movements are the rhythmic contraction and relaxation of the muscles in the lining of the alimentary canal,which push the food forward through the digestive tract.

(A) The shape of guard cells is regulated by the turgor pressure within them.
When water enters the guard cells through osmosis,they become turgid and swell,causing the stomatal pore to open.
Conversely,when water leaves the guard cells,they become flaccid and shrink,causing the stomatal pore to close.
Therefore,the change in the shape of guard cells is primarily due to the amount of water present in the cells.

(B) Green plants are called 'producers' because they possess chlorophyll,which allows them to capture solar energy.
They use this energy to convert inorganic substances like $CO_2$ and $H_2O$ into organic food (glucose) through the process of photosynthesis.
Since they synthesize their own food,they are known as autotrophs or producers.

(N/A) Autotrophs: Organisms that can synthesize their own food from simple inorganic substances like $CO_2$ and $H_2O$ using sunlight and chlorophyll are called autotrophs.
Example: All green plants.
Heterotrophs: Organisms that cannot synthesize their own food through photosynthesis and depend on other organisms for their nutritional requirements are called heterotrophs.
Example: All animals.
Decomposers: Organisms that break down complex organic matter present in dead remains of plants and animals into simpler substances are called decomposers.
Example: Bacteria and Fungi.

(N/A) Bile makes the acidic food coming from the stomach alkaline,which enables pancreatic enzymes to act. Bile salts emulsify large fat globules into smaller ones,which increases the surface area for enzyme action,thereby increasing the efficiency of digestion.
$(b)$ The products formed after complete digestion are:
Carbohydrates: Glucose
Proteins: Amino acids
Fats: Fatty acids and glycerol

(N/A) Refer to the provided diagram of the human alimentary canal.
$(b)$ Bile does not contain any digestive enzymes,yet it is essential for digestion due to the following reasons:
$(i)$ It makes the acidic food coming from the stomach alkaline,which is necessary for the action of pancreatic enzymes.
$(ii)$ It contains bile salts that help in the emulsification of fats,breaking down large fat globules into smaller ones to increase the efficiency of enzyme action.

(N/A) Enzymes are biological catalysts that accelerate the rate of biochemical reactions within living organisms. They are primarily proteinaceous in nature.
In humans,the enzyme $Lipase$ is responsible for the digestion of fats (lipids) into fatty acids and glycerol.

(N/A) Functions of bile juice:
$(i)$ It emulsifies large fat globules into smaller ones,thereby increasing the surface area for enzyme action.
$(ii)$ It makes the acidic food coming from the stomach alkaline,which is essential for the activity of pancreatic enzymes.
$(b)$ Differences between pepsin and trypsin:
$1.$ Pepsin: It acts on proteins in an acidic medium in the stomach.
$2.$ Trypsin: It acts on proteins in an alkaline medium in the small intestine.

(N/A) Liver: Produces bile juice. Bile salts present in it emulsify large fat globules into smaller ones,facilitating digestion. It also stores excess glucose in the form of glycogen.
Gall bladder: Stores and concentrates the bile juice produced by the liver until it is needed for digestion in the small intestine.
Villi: These are numerous finger-like projections present on the inner lining of the small intestine. They increase the surface area for the absorption of digested food. The villi are richly supplied with blood vessels that transport the absorbed nutrients to every cell of the body.

(N/A) Autotrophic organisms fulfill their energy requirements through a process called $Photosynthesis$.
In this process, autotrophs take in external substances like $CO_2$ and $H_2O$ and convert them into energy-rich carbohydrates in the presence of sunlight and chlorophyll.
The chemical reaction is: $6CO_2 + 12H_2O \xrightarrow[Chlorophyll]{Sunlight} C_6H_{12}O_6 + 6O_2 + 6H_2O$.
The carbohydrates that are not immediately used by the plant are stored in the form of $Starch$.

(N/A) The site of photosynthesis is the chloroplast,which is a green-coloured plastid found in plant cells.
$(b)$ The basic requirements for the process of photosynthesis are:
$(i)$ Carbon dioxide $(CO_2)$
$(ii)$ Water $(H_2O)$
$(iii)$ Sunlight (as an energy source)
$(iv)$ Chlorophyll (the photosynthetic pigment)

(N/A) $(i)$ Pepsin is secreted by the gastric glands present in the stomach wall.
$(ii)$ Salivary amylase is secreted by the salivary glands located in the mouth.
$(iii)$ Trypsin is secreted by the pancreas.
$(iv)$ Lipase is secreted by the pancreas.
$(b)$ $(i)$ The small intestine is the primary site for the absorption of digested food into the bloodstream.
$(ii)$ The large intestine is responsible for the absorption of water and salts from the undigested food material.

(N/A) $(i)$ Keep a potted plant in a dark room for $48-72$ hours to destarch its leaves. (Fig. $(a)$)
$(ii)$ Cover a portion of a leaf on both sides with strips of black paper using paper clips. This prevents sunlight from reaching the covered area. (Fig. $(b)$)
$(iii)$ Place the plant in bright sunlight for $4-6$ hours.
$(iv)$ Detach the leaf and remove the black paper strips. Perform a starch test by boiling the leaf in alcohol to remove chlorophyll and then adding iodine solution.
$(v)$ The part of the leaf that was covered with black paper does not turn blue-black,indicating the absence of starch. (Fig. $(c)$)
$(vi)$ The uncovered part of the leaf turns blue-black,indicating the presence of starch. This proves that sunlight is essential for photosynthesis.

(D) The opening and closing of the stomatal pore is regulated by the turgor pressure within the guard cells.
When water enters the guard cells,they become turgid and swell,causing the stomatal pore to open.
Conversely,when water leaves the guard cells,they become flaccid,causing the stomatal pore to close.
Therefore,the movement of water into and out of the guard cells is the primary factor determining the state of the stomata.

(A) Plants require nitrogen for the synthesis of proteins and other compounds.
Although nitrogen is abundant in the atmosphere,plants cannot absorb it directly in its gaseous form $(N_2)$.
Most plants absorb nitrogen from the soil primarily in the form of nitrates $(NO_3^-)$ and nitrites $(NO_2^-)$.
Some plants can also absorb nitrogen in the form of urea or ammonium compounds,which are converted into nitrates by soil bacteria.
Therefore,the forms in which most plants absorb nitrogen are nitrates and nitrites,and sometimes urea.