Nutrition Questions in English

(B) The process of digestion begins in the mouth (buccal cavity).
Salivary glands secrete saliva,which contains the enzyme salivary amylase (also known as ptyalin).
This enzyme is the first to mix with food and it starts the breakdown of complex carbohydrates (starch) into simpler sugars like maltose.

(C) Salivary amylase is an enzyme present in the saliva that initiates the chemical digestion of carbohydrates.
It specifically acts on starch (a complex carbohydrate) and breaks it down into simpler sugars like maltose.
If salivary amylase is absent,the breakdown of starch into sugars in the mouth cavity will be significantly affected or inhibited.

(D) The stomach wall secretes gastric juice,which contains hydrochloric acid $(HCl)$,pepsin,and mucus.
$HCl$ creates an acidic medium necessary for the activation of the enzyme pepsin.
However,$HCl$ can be corrosive to the stomach lining.
Mucus is secreted by the goblet cells in the stomach lining to form a protective layer.
This layer prevents the acid from damaging the stomach wall,thus protecting it from erosion and ulcers.

(A) The liver produces bile,which is stored in the gallbladder. Bile is released into the duodenum,which is the first part of the small intestine. This bile helps in the emulsification of fats,breaking down large fat globules into smaller ones to facilitate digestion by enzymes.

(B) The iodine test is a chemical test used to detect the presence of starch in a sample.
When iodine solution ($I_2$ in $KI$) is added to a substance containing starch,it forms a starch-iodine complex,which results in a characteristic blue-black colour.
Since the rice water turned blue-black upon the addition of iodine,it confirms the presence of starch in the rice water.
Therefore,the correct option is $B$.

(C) The process of digestion begins in the mouth and continues in the stomach.
However,the final digestion of food,including carbohydrates,proteins,and fats,is completed in the small intestine.
The small intestine receives secretions from the liver (bile) and the pancreas (pancreatic juice),and its walls secrete intestinal juice.
These enzymes break down complex food molecules into their simplest absorbable forms,such as glucose,amino acids,and fatty acids,which are then absorbed into the bloodstream.

(D) Pancreatic juice contains several enzymes that play a crucial role in digestion.
$1$. $Trypsin$ is a proteolytic enzyme that breaks down proteins into smaller peptides.
$2$. $Lipase$ is an enzyme that acts on emulsified fats and breaks them down into fatty acids and glycerol.
Therefore,the correct function is that $trypsin$ digests proteins and $lipase$ digests emulsified fats.

(A) The statement is $True$. Bile is a digestive juice produced by the liver cells (hepatocytes). It is alkaline in nature due to the presence of bile salts,which help in the emulsification of fats. It is temporarily stored and concentrated in the gall bladder before being released into the small intestine.

(A) The stomach secretes gastric juice,which contains hydrochloric acid $(HCl)$.
This acid creates an acidic environment with a low $pH$ (typically between $1.5$ and $3.5$).
Pepsin is a digestive enzyme that breaks down proteins into smaller peptides.
It is secreted in its inactive form,pepsinogen,and requires this low $pH$ environment to be converted into its active form,pepsin,to function effectively.

(B) Biochemical catalysts are substances that increase the rate of chemical reactions occurring within living organisms without being consumed in the process.
These biological catalysts are known as $Enzymes$.
Most $Enzymes$ are proteinaceous in nature and are essential for metabolic processes such as digestion,respiration,and $DNA$ replication.

(A) The conversion of milk into curd is a biological process carried out by lactic acid bacteria,commonly known as $Lactobacillus$.
These bacteria produce lactic acid,which coagulates the milk protein called casein,resulting in the formation of curd.
$Lactase$ is an enzyme that breaks down lactose (milk sugar),$Sucrase$ breaks down sucrose,and $Zymase$ is involved in fermentation.
Since the question asks for the agent responsible for this conversion,$Lactobacillus$ is the correct biological agent.

(D) Green plants are autotrophs that perform photosynthesis. During this process,they capture solar energy (sunlight) and convert it into chemical energy stored in the form of glucose (organic compounds). Therefore,the correct answer is chemical energy.