AQA biology B3 - Organisation and the digestive system

Define + example of a cell

The smallest structural and functional part of an organism e.g. red blood cell

Define + example of a tissue

A group of cells with a similar structure and function that work together. e.g. muscular tissue

Define + example of an organ

A collection of tissues working together to preform a particular function e.g. Stomach

Define + example of an organ system

A collection of organs working together to preform specific functions e.g. Digestive system

List the tissues in the stomach and their functions (3)

Muscular tissue - To churn the food and digestive juices together
Glandular tissue - To produce enzymes
Epithelial tissue - covers inside and outside of organ, protecting it

List in order the organs in the digestive system along with their purpose

Mouth - breaks apart food and and begins digesting starch
Gullet - Transports food to stomach
Liver - produces bile
Gall bladder - stores bile
Stomach - Breaking down large insoluble molecules into small soluble ones
Pancreas - produces digestive enzymes
Small intestine - Further breaks down molecules and absorbs them
Large intestine - absorbs water
Rectum + Anus - gets rid of waste

How is the small intestine adapted to its function

It has an extremely large surface area and has a thin absorption lining allowing molecules to pass easily into the blood stream

Explain the process of digestion

The food is first broken into smaller pieces by the mouth, it is then sterlised by the stomach acid and is also is broken down by various enzymes. The food then goes into the small intestine and is broken down further and the nutrients are absorbed into the blood stream. The undigested material has its water extracted and released as waste

Describe the structure of starch

A polymer made up many glucose molecules

Describe the structure of proteins

A polymer made up of many amino acids arranged in different orders

Describe the structure of lipids

A non polymer made up of one glycerol and 3 fatty acids, what these fatty acids are dictates what lipid it will be

What do carbohydrates do

A relatively short term energy source

What do Lipids do

Long term and efficient energy store

What do proteins do

Build up cells and tissues in body

Food test for Starch

Turns yellow red iodine into blue black colour

Food test for sugar

Turns blue Benedict's solution brick red

Food test for protein

Turns blue biuret reagent purple

Test for Lipids

Turns ethanol cloudy

Define enzyme

A protein produced by the body that acts as a catalyst

How do enzymes work

They bind (a) specific substrate(s) to their active site and speed up the process of it breaking apart or joining togethe

What model do we use to represent enzymes

Lock and key model

How do enzymes control the metabolism

The faster the enzymes work and the more of the there are increase the amount of reactions happening in the body at any one time

How do changes in pH and temperature effect the speed at which an enzyme reacts

Enzymes have an optimum pH and temperature at which they work the best at. If these get too extreme the enzyme will get denatured and no longer work

What enzymes are used in digestion

Amylase
Protease
Lipase

Where is amylase formed

Salivery glands
Pancreas
Small intestine

Where is lipase produced

Pancreas
Small intestine

Where is protease produced

Stomach
pancreas
Small intestine

What does bile do

Increases the surface area of (emulsifies) lipids, making it easier for lipase to do its job

Why does acid in the stomach increase the efficiency of pepsin

Because the acid in the stomach is pepsin's optimum temperature and thus makes it speed up reactions more