Adaptations For Nutrition

Question 1

What type of nutrition do some protists such as the amoeba use?

Answer 1

Holozoic

Question 2

How do amoeba obtain nutrients such as oxygen and glucose?

Answer 2

Diffusion, facilitated diffusion and active transport

Question 3

How do amoeba take in large food molecules such as bacteria?

Answer 3

By endocytosis, where the food molecules are surrounded by membranes forming vacuoles

Question 4

How are indigestible remains excreted in amoeba?

Answer 4

By exocytosis

Question 5

How are food vacuoles digested in amoeba?

Answer 5

The food vacuoles fuse with lysosomes containing hydrolysis enzymes which digest the contents of the food vacuoles. The products of digestion are then absorbed into the cell cytoplasm

Question 6

What are hydra?

Answer 6

Multicellular fresh water animals who are in the same phylum as jellyfish

Question 7

Do hydra have a differentiated or undifferentiated immune system?

Answer 7

Undifferentiated

Question 8

How does digestion work in hydra?

Answer 8

Tentacles move paralysed prey in through the mouth and into a body cavity where it is digested, and the products are absorbed into body cells and the indigestible remains are egested through the mouth.

Question 9

What is a tube gut?

Answer 9

A digestive system that is a tube with two openings, where food is ingested at the mouth and indigestible waste is egested at the anus

Question 10

Why must food be digested?

Answer 10

-So we can absorb all the nutrients out of it
-Molecules must be soluble to be transported into blood
-Waste can be excreted easily
-Food molecules are too big to cross membranes

Question 11

What is ingestion?

Answer 11

Taking food into the body through the mouth

Question 12

What is digestion?

Answer 12

The breakdown of large insoluble molecules into soluble molecules that are small enough to be absorbed into the blood

Question 13

What are the two types of digestion?

Answer 13

1.Mechanical digestion, where food is cut up and crushed by teeth and muscle contractions of the gut wall, which increases the surface area over which enzymes can act
2.Chemical digestion, where food is broken down using digestive enzymes, bile and stomach acid

Question 14

What is absorption?

Answer 14

The passage of small soluble molecules and ions through the gut wall and into the blood

Question 15

What is egestion?

Answer 15

The elimination of indigestible waste

Question 16

What is the gut?

Answer 16

A long, hollow, muscular tube, where digestion and absorption occur. It allows movement of contents in one direction only. Each section is specialised and forms particular steps in digestion

Question 17

What is peristalsis?

Answer 17

The wave of muscular contractions and relaxations of the gut wall which propel the contents along the whole length of the gut. Circular muscles contractions behind the bolus of food and then relax after the wave of contraction has passed

Question 18

What is the function of the mouth?

Answer 18

Ingestion, mechanical digestion of food by teeth and chemical digestion of starch by salivary amylase

Question 19

What is the function of the oesophagus?

Answer 19

Carriage of food to the stomach by peristalsis

Question 20

What is the function of the stomach?

Answer 20

Contraction of stomach muscles to mechanically digest food. Secretion of hydrochloric acid. Chemical digestion of proteins by enzymes

Question 21

What is the function of the duodenum?

Answer 21

Receives pancreatic juice from the pancreas and bile from the gall bladder. Chemical digestion of carbohydrates, fats and proteins by enzymes

Question 22

What is the function of the ileum?

Answer 22

Chemical digestion of carbohydrates, fats and proteins by enzymes, and absorption of digested food

Question 23

What is the function of the large intestine?

Answer 23

Absorption of water

Question 24

What is the function of the rectum?

Answer 24

Storage of faeces

Question 25

What is the function of the anus?

Answer 25

Site of egestion

Question 26

What are the four tissue layers surrounding the lumen of the gut?

Answer 26

The serosa, muscularis, submucosa and mucosa

Question 27

What is the function of the serosa?

Answer 27

It is the outermost layer. It contains tough connective tissue which protects the gut wall, and helps to reduce friction with other abdominal organs during peristalsis

Question 28

What is the function of the muscularis?

Answer 28

Composed of two layers, the inner circular muscles and the outer longitudinal muscles. They make coordinated waves of contraction (peristalsis) pushing the bolus of food along the alimentary canal

Question 29

What is the function of the submucosa?

Answer 29

Consists of connective tissue containing blood and lymph vessels which remove the absorbed products of digestion. This layer also contains the nerves which coordinate peristalsis

Question 30

What is the function of the mucosa?

Answer 30

It lines the gut wall and is the inner-most layer. The epithelium secretes mucus which lubricates and protects the mucosa. In some regions of the gut it secretes digestive juices and in others it absorbs digested food