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.

Amino acids, glucose and Cl are absorbed by simple diffusion.

1. Since humans form two sets of teeth during their life time, the milk teeth and permanent teeth, dentition is diphyodont.
2. Since human teeth are of different types, dentition is heterodont.

Mucosa of the small intestine is adapted for the absorption of food by having villi and brush-bordered epithelium.

Caecum.

Appendix is a vestigial organ and plays no role in digestion in human beings.

Parotid gland.

To convert complex substances into simple absorbable substances digestion is necessary.

Liver, abile.

Goblet cells; they secrete mucus.

1. Pancreas is located between the two limbs of the “U”-shaped duodenum.
2. Since pancreas contains both endocrine part (to secrete hormones) and exocrine part (to secrete digestive enzymes), it is called a compound gland.

Fat is digested by bile juice and pancreatic lipases.

The type of attachment where teeth are embedded in the socket of jaw bone is called the codont.

Provision of separate socket for separate tooth, in the jaw bone is called thecodont.

Mucus of saliva helps in lubricating and adhering the masticated food particles into a bolus.

Mesothelium refers to the epithelium of visceral organs.

An enzyme enterokinase, secreted by the intestinal mucosa activates proenzyme trypsinogen into active trypsin, which in turn activates the other enzymes in the pancreatic juice.

Excess dehydration leads to loss of salts from the body. This disturbs the electrolyte balance of the body.

Pancreatic juice and bile are released through hepato-pancreatic duct.

As soon as the drug comes in contact with mucosa of mouth and lower side of the tongue, it is absorbed by the blood capillaries. Some drugs are also absorbed in large intestine.

Dipeptidase.

It is due to these waves of contraction of the circular muscle that passes along the stomach and oesophagus that the food is pushed into the relaxed portion.

1. Salivary amylase catalyses the breakdown of starch into maltose.
2. Lysozyme acts as an antibacterial agent and prevents infection.

pH range should be alkaline.

• Digestion is the process of conversion of complex food substances into simple absorbable forms.
• The complex biomacromolecules cannot be absorbed by our body cells in their original form; so they have to be digested into simple forms for absorption.

The three major parts of stomach are:

1. Cardiac.
2. Fundus.
3. Pylorus.

Epiglottis prevents the entry of food into the trachea, by closing its opening called glottis.

Deglutition is the process in which the food bolus from the buccal cavity is conveyed through the pharynx into the oesophagus.

• Lipases digest fats.ba
• Glycerol and fatty acids are the end products.

1. Caecum, colon and rectum.
2. Caecum harbours the symbiotic microbes.

If the bile duct is blocked completely, the bile will fail to reach the small intestine and the digestion of fats gets affected.

NO, bile is secreted by hepatic cells (liver cells) and is stored and concentrated in the gall bladder.

Condition is known as jaundice in which discoloration of the skin and white portion of eye takes place.

Sublingual.

Alcohol, simple sugars.

Two anatomical adaptations that can increase absorption in small intestine are:

1. Long size of small intestine.
2. Presence of villi and microvilli.

Absorption of amino acids and glycerol takes place in the small intestine.

The absorption of water, simple sugars, alcohol and some lipid soluble drugs take place by the stomach wall.

Lacteal.

In reflux oesophagitis, the oesophagus does not function properly?

1. Anus helps in eliminating the unabsorbed food.
2. Anal sphincter regulates the unabsorbed food, which releases it in small amounts into the small intestine.

Amylase.

When liver does not function properly, it is unable to metabolise bilirubin and biliverdin which get accumulated in blood thus, causes jaundice.

If goblet cells are non-functional for some reason, this will adversely affect smooth movement of food down the intestine due to the absence of mucin. These glands secrete mucus which along with succus entericus which helps in digestion and movement of food material in the alimentary canal.

Enterokinase activates pancreatic gland to secrete digestive enzymes.

Only emulsified fat can be absorbed by intestinal wail.

• Liver is affected.
• Due to deposition of bile pigments, the eyes and skin become yellow.

Between the bases of villi in the mucosa of intestine.

The sequence of organic food to be digested by the body after a prolonged fasting will be: Carbohydrates → Fats → Proteins.

Taste buds are located in the papillae on the upper surface of the tongue.

Dipeptides, disaccharides and glycerides are broken down into simple substances in the region of small intestine called duodenum.

70% of faeces is water, while other 30% are solids in nature.

Small nutrients are absorbed by active transport, some are absorbed by the facilitated transport and simple diffusion.

Because of the acidic pH in the stomach.

Ileocaecal valve is present where an ileum of small intestine enters the caecum of the large intestine. It helps in preventing the backflow of faecal matter from caecum into ileum.

Pancreatic juice contains proenzymes trypsinogen, chymotrypsinogen and procarboxy peptidases.

Salivary amylase would not be able to digest starch into simple sugar e.g., iso maltose.

Salivary gland and pancrease. It digests complex carbohydrates.

• The mucosa is folded into finger-like projections, called villi.
• The cells lining the villi bear microvilli and form the brush-bordered epithelium; these two features this increase the surface area for absorption.
• The villi are richly supplied with a network of blood capillaries and a large lymph vessel, lacteal, for easy absorption of nutrients.

The transport of water depends on the osmotic grandient across the intestinal (large) wall.

Tongue is attached to the floor of the buccal cavity by the frenulum.

Presence of villi (finger-like projection).

Skin and eyes turn yellow in liver infection.

The act of swallowing is called deglutition.

Metabolism of sugar.

The mucus and the bicarbonates of the gastric juice protect the gastric epithelium.

Buccal cavity performs the following functions:

1. Mastication of food.
2. Mixing of saliva.

These are found in small intestine part of alimentary canal.

The faeces in the rectum initiate a neural reflex causing an urge for its removal.

It is present where the ileum enters the caecum - It prevents the backflow of faecal matter from caecum into ileum.

Diarrhoea and constipation are the conditions in which abnormal frequency of bowel movement occurs.

Human teeth are heterodont.

When bile from the liver get crystallised, person suffers because of the stone formation in kidney or urinary bladder in the body.

Goblet cells are located in the intestinal mucosal epithelium and secrete mucus.

Fatty acids and glycerols are not absorbed directly Chylomicrons Micelles into the bloodstream. Thus, they are absorbed in the form of small droplets called micelles.

Enterokinase is protease enzyme of small intestine, which does not directly take part in the protein digestion.

Pepsin.

1. Vomiting is the reflex action of ejection of the stomach contents through the mouth.
2. It is controlled by the vomit centre in the medulla of the brain.
3. Nausea precedes vomiting.

Parotid glands (a type of salivary gland) is situated in: the upper palate on either side of the cheek.

The secretions of the brush-bordered epithelium and the goblet cells of intestinal mucosa, constitute succus entericus.

Glucose, a monosaccharide is absorbed by simple diffusion.

1. Bolus.
2. Chyme.

Hydrochloric acid (HCI) is the chemical substance that changes pepsinogen into pepsin.

Epiglottis prevents the entry of food into the trachea, by closing its opening called glottis.

Protection from HCI.

Oxyntic cells (parietal cells) are present in the epithelial lining of stomach that secretes gastric acid, i.e., HCI.

Cystic duct.