Biology 1 Marks Question

2. Intestinal juice.

​​​​​​​Solution:
Succus entericus is another name for intestinal juice. It is secreted by the intestinal gland. Intestinal juice contains a variety of enzymes such as maltase, lipases, nucleosidases, dipeptidases, etc.

1. pepsin, lipase and rennin.

​​​​​​​Solution:
Gastric juice contains pepsin, lipase, and rennin. Pepsin is secreted in an inactive form as pepsinogen, which is activated by HCl. Pepsin digests proteins into peptones. Lipase breaks down fats into fatty acids. Rennin is a photolytic enzyme present in the gastric juice. It helps in the coagulation of milk.

• Amylase is secreted by the salivary glands into the buccal cavity and also by pancreas, into duodenum.
• Amylase acts on starch and breaks it into maltose.

Pancreatic juice is the source of trypsin which hydrolyses proteins into peptides.

The outermost layer in the wall of the stomach is Serosa.

The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall the food at this stage is called chyme.

Mucous membrane of stomach provides protection from HCI.

Rennin is a proteolytic enzyme found in infants gastric juice.

The two sets of teeth are:

1. Milk teeth/ deciduous teeth.
2. Permanent/ adult teeth.

As bread is full of starch, the enzyme secreted in our mouth for digesting starch starts breaking down carbohydrates present in starch converting into simple sugars. Hence, it tastes sweeter after some time.

Human beings get two sets of teeth during their life. This phenomenon is called diphyodont.

The pH of the mouth becomes alkaline for the activity of salivary amylases. Its value is near 6.5 for best amylase activity.

• Three pairs.
• Parotid, sub-mandibular or submaxillary and sublingual.

Brunner's glands; their secretion helps in providing an alkaline medium for enzyme actions in the duodenum.

It regulates the opening of the hepato-pancreatic duct into the duodenum.

Hepatopancreatic duct helps in bringing secretions from gall bladder and pancreas to the duodenun.

Gastro-oesophageal sphincter.

Saliva contains enzymes that digest starch.

The amount of heat liberated from complete combustion of lg food in a bomb calorimeter is its gross calorific value or gross energy value.

Epiglottis is a flap-like structure, that closes the wind pipe during swallowing of food.

Hepato-pancreatic duct.

1. Rugae.
2. Villi.

Certain herbivores possess large size caecum, so that it can host large number of bacteria that aid in easy enzymatic breakdown of plant materials such as cellulose which they take as a food.

• Enamel is the substance.
• The hard surface helps in mastication.

Inflammation of the intestinal tract.

Pancreas.

In the thecodont type of dentition, separate sockets are provided for tooth in the jaw bone.

Mastication of food and facilitation of swallowing.

Bilirubin and Biliverdin.

• PEM refers to dietary deficiencies of proteins and total food calories.
• Kwashiorkar and marasmus are its two forms.

Fat + Lipase → Diglycerides Monoglycerides. Di/ Monoglycerides + Lipase → Fatty acids + Glycerol.

1. Micelles.
2. Chylomicron.

Carbohydrate → Glucose Protein → Amino acid

Glisson's capsule.

Absorption of water, some minerals and drugs takes place in the large intestine.

1. pH 6.8
2. pH 1.8

1 joule is the amount of energy required to raise the temperature of 1g of water by 1°C.

Duodenum, jejunum, ileum.

Small intestine.

Fats are broken down into di- and monoglycerides with the help of lipases.

The process of making food absorbable by mechanically and enzymatically breaking it down into simpler chemical compounds in the digestive tract.

Nucleotides and nucleosidases.

Peristalsis.

Fructose is absorbed in small intestine by the facilitated diffusion.

1. It is activated by the hydrochloric acid secreted by gastric glands, into its active form, pepsin.
2. It acts on proteins.

The actual amount of energy from combustion of 1g of food is the physiological value of food.

Oesophagus opens into the stomach.

Gastric glands of stomach mucosa have oxyntic cells which secrete HCL.

This means that the digestion of proteins is not taking place in the person's stomach due to the absence of enzyme rennin and pepsin in gastric juice.