NCERT Class X Science Class: Chapter – 6. Life Processer – Part-13 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 76:

Explain the importance of soil for plant growth.


Soil is important for plants because it holds roots that provide support for plants and stores nutrients. Detective Le Plant is searching for secrets in the soil. Help him uncover the ingredients of soil that are important to plant growth.

Question 77:

Draw the diagram of alimentary canal of man and label the following parts.

Mouth, Oesophagus, Stomach, Intestine


Image the Alimentary Canal of Man

The digestion of carbohydrates (starch) starts in the mouth. The saliva has salivary amylase or ptyalin enzyme which acts on the starch and converts it into maltose sugar. The partially digested food reaches the stomach where the food gets mixed with gastric juice secreted by gastric glands. The gastric juice contains large quantities of mucus, and pepsin. The enzyme pepsin acts on proteins and coverts them into peptones and proteases. The gastric lipase emulsifies fats.

Bile juice secreted from liver lipids into small droplets.

Pancreas secretes pancreatic juice which contains the pancreatic amylase, trypsin and lipase. Pancreatic amylase digests the leftover starches into maltose. Trypsin converts peptones and proteases into small peptides. Lipase acts on small droplets and converts them into triglycerides.

The food reaches the small intestine where complete digestion of food takes place in the presence of an enzyme called stuccos entericus. The maltose converts into glucose, peptide emulsifies into amino acids and the triglycerides emulsifies into fatty acids and glycerol.

Question 78:

How do carbohydrates, proteins and fats get digested in human beings?


(1) Carbohydrates: The human saliva contains an enzyme called slivery amylase which digests starch (carbohydrate) present in food into sugar. Thus, the digestion of carbohydrate begins in the mouth itself.

In duodenum, pancreatic juice which contains digestive enzymes like pancreatic amylase, breaks down the starch (carbohydrate) . It is further digested in jejunum by intestinal juice.

Starch is digested in the mouth by salivary amylase. Other forms of carbohydrates are digested in the small intestine.

Starch + Salivary Amylase ⇾ Sucrose

Maltose + Maltase ⇾ Glucose

Lactose + Lactase ⇾ Glucose + Galactose

Image Digesion of Carbohydrates Occurs

(2) In stomach, proteins are digested by gastric juice, in duodenum by pancreatic juice and in jejunum by intestinal juice.

(3) In duodenum and jejunum fats are digested by pancreatic juice aided by bile salts. Infants it is digested in stomach.

Question 79:

Explain the mechanism of photosynthesis.


The process by which green plants make their own food in presence of sunlight, chlorophyll and water is known as photosynthesis. Chlorophyll the green coloured pigment present in plant is responsible for performing photosynthesis because it has the ability to absorb sunlight and convert it into food.

The three main steps of Mechanism of photosynthesis are:

1. Conversion of light energy into chemical energy and splitting water molecules into hydrogen and oxygen.

2. Reduction of carbon dioxide to carbohydrates.

3. Formation of