Biology- Year 10- Animal Nutrition

Question 1

By which mode of nutrition do animals feed? Explain

Answer 1

Animals feed by holozoic nutrition. Holozoic nutrition is when an organism goes through 5 stages to eat their food;
Ingestion, Digestion, Absorption, Assimilation and Egestion.

Question 2

How does Holozoic nutrition happen in humans?

Answer 2

Ingestion- through the mouth
Digestion- in the mouth, stomach and intestines.
Absorption- into the blood and lymphatic systems
Assimilation- Around the body
Egestion- through the Anus.

Question 3

How does holozoic nutrition happen in the amoeba?

Answer 3

Ingestion- through cell membrane
Digestion- food vacuole
Absorption- in the cytoplasm
Assimilation- Around the cell
Egestion- through cell membrane

Question 4

What are the systems of organs called that digest food in humans and what is it made up of?

Answer 4

The digestive system. It is made up of a 9m long alimentary canal also called the gut together with the associated organs the pancreas and liver. ( Contents within the gut is considered to be outside the human body)

Question 5

Give the function of the digestive system and how food is broken down. (The 2 ways)

Answer 5

The function of the digestive system is to break down solid food into small and soluble food molecules. Food can be broken down mechanically or chemically.

Question 6

Describe the mechanical breakdown of food.

Answer 6

Mechanical breakdown occurs in the form of chewing ( in the mouth) and churning (in the stomach). Mechanical breakdown increases the foods surface are to facilitate enzyme action.

Question 7

Describe the chemical breakdown of food.

Answer 7

Chemical breakdown of food involves digestive enzymes- biological catalysts that break down large food molecules into small and soluble ones.

Question 8

What is the alimentary canal made up off and what is there to protect it?

Answer 8

The alimentary canal is made up of epithelium tissue. The epithelium tissue produces slimy mucus to protect its cells from excessive wear and tear. Mucus also helps lubricate the food moving along the gut.

Question 9

What is the first part of the human digestive system? Explain and describe it.

Answer 9

The buccal cavity or mouth cavity. ingestion takes place here. At the back of the mouth cavity there is the pharynx or the throat. Teeth inside the mouth chew the food. This is were the mechanical breakdown of food occurs by chewing.

Question 10

Give the four types of teeth their shape, function and where they are found in the buccal cavity.

Answer 10

Molars- Behind premolars, flattened+ 4 cusps, to crush and grind.
premolars- Behind canines, flattened, 2 cusps, to crush or grind.
Incisors- at the front, chisel, to cut
canines- behind incisors, pointed, to hold and pierce. (teeth are found in the skull)

Question 11

Where does saliva come from? What does it contain, when is it triggered?

Answer 11

Saliva comes from the three pairs of salivary glands (under the tongue). It contains salivary amylase which breaks down starch into maltose. It also contains mucin which lubricates the food into a bolus. It is triggered by the presence of food in the mouth or by thinkin of food.

Question 12

What are the steps of swallowing?

Answer 12

1. Tongue rises upwards- the bolus is forced to the back of the mouth.
2. soft palate rises- to close connection to the nasal cavity.
3. Larynx cartilage rises- so that glottis lies under the back of the tongue.
4. Epiglottis covers the glottis- to prevent choking.

Question 13

what is the function of the oesophagus and what are the muscular contractions called.

Answer 13

Its function is to transfer food from the buccal cavity to the stomach. It has circular and longitudinal muscles. to move the food down to the stomach the muscles contract. This is called peristalsis.

Question 14

What happens in the stomach and what are its adaptations?

Answer 14

The stomach is a muscular bag that can hold up to two liters of food.
Its functions are for it to store food and to break down food into chyme.
Chyme is released into the small intestines slowly through the pyloric sphincter.
the stomach walls contain gastric glands and release gastric juice once food enters the stomach.
Gastric juice contains HCl and pepsin. Pepsin turns proteins in the stomach to peptides.
The stomach has a pH of 2 due to the HCl. HCl- kills most bacteria and provides an ideal pH for pepsin to work.
In babies the enzyme renin is found so as to solidify milk and get absorbed better.
The stomach contains mucus to prevent self-digestion.
Churning happens in the stomach.

Question 15

What are the two parts of the small intestine called?

Answer 15

The first part- duodenum
The second part- ileum

Question 16

What happens in the duodenum?

Answer 16

Chyme is released from the stomach through the pyloric sphincter into the duodenum. It receives bile from the liver and pancreatic juice from the pancreas.

Question 17

What is bile? Explain.

Answer 17

Bile is a green pigment made by the liver and stored in the gall-bladder. It is secreted into the duodenum via the bile duct so it emulsifies fats. Emulsification is the process of breaking down fats into smaller parts for more surface area for the enzyme lipase to act in them. Biles green colour comes from bilirubin. ( formed when worn out red blood cells are formed in the liver).

Question 18

What does pancreatic juice contain? Explain.

Answer 18

Pancreatic juice contains pancreatic amylase- it acts on remaining starch that was not broken down in the mouth into maltose.
Trypsin- it breaks down proteins into peptides and amino acids.
Lipase- breaks down lipids into 3 fatty acids and glycerol.

Question 19

What happens in the ileum? explain.

Answer 19

In the ileum the completion of digestion occurs as well as absorbing small food products. Enzymes are found bound to cell membranes of epithelial cells lining the ileum.

Question 20

What does the enzyme Maltase act upon?

Answer 20

Maltose- glucose

Question 21

What does the enzyme Sucrase break down?

Answer 21

Sucrose- glucose and fructose

Question 22

What does the enzyme lactase Break down?

Answer 22

Lactose- glucose and galactose

Question 23

What does the enzyme peptidase break down?

Answer 23

peptides- amino acids.

Question 24

What do pepsinogen and trypsinogen do? how are they activated?

Answer 24

Pepsinogen and trypsinogen are the inactive forms of pepsin and trypsin. They are secreted in an inactive form so as to prevent self-digestion. Pepsinogen is activated by HCl and trypsin is activated by the enzyme enterokinase.

Question 25

What parts make up the large intestine?

Answer 25

the caecum, appendix, colon and the rectum.

Question 26

What is the function of the caecum and appendix?

Answer 26

have no use

Question 28

What happens in the colon?

Answer 28

The colon retains water. The undigested part of the food is moves to the colon to absorb water and the remaining become faeces.

Question 29

what is the function of the rectum?

Answer 29

Faeces are stored in the rectum until egestion or defecation takes place through the anus.

Question 30

Where is the site where the most food absorption happens?

Answer 30

Food absorption happens mostly in the small intestine the ileum. t contains a very large surface area- it contains villi and microvilli, it is folded and it is very long. It has a very thin epithelium and a dense network of blood capillaries.