Digestion and Vaccination Year 10

Question 1

What are cells?

Answer 1

Cells are the basic building blocks of all living organisms

Question 2

What are tissues?

Answer 2

A tissue is a group of cells with a similar structure and function

Question 3

What are organs?

Answer 3

Organs are collections of tissues performing specific functions

Question 4

What are organ systems

Answer 4

Several organs work together to carry out a specific function, eg. the digestive system.

Question 5

Label the digestive system (see goodnotes)

Question 6

Describe what the mouth, oesophagus and stomach do in the digestive system

Answer 6

• mouth- has teeth to cut the food into tiny bits and produces saliva that contains amylase
• oesophagus - has rings of muscle to push the food down to the stomach
• stomach - has hydrochloric acid to kill bacteria on food, has protease to digest protein

Question 7

Describe what the pancreas, liver, and gall bladder do in the digestive system

Answer 7

• pancreas - produces amylase, protease and lipase to be secreted into the small intestine
• liver - makes bile and stores it in the gall bladder
• gall bladder - stores bile and the bile passes into the small intestine via the bile duct
• bile - emulsifies large fat droplets into smaller droplets to increase their surface area so that lipase enzymes can work faster and neutralises stomach acid to maintain the optimum pH for the enzymes in the small intestine.

Question 8

Describe what the small intestine, large intestine, and rectum do in the digestive system

Answer 8

• small intestine - has amylase, lipase, and protease to digest. The digested food molecules are absorbed here as well via villi and microvilli
• large intestine - reabsorbs water from food
• rectum - holding area for faeces, egestion (passing out remains of food through the anus) happens here

Question 9

What are enzymes

Answer 9

they are biological catalysts (catalysts speed up the rate of a reaction but are not used up in the reaction)

Question 10

What is the lock and key theory?

Answer 10

• enzymes have an area called the active site that has the correct shape to bind to one molecule
• the molecule is called substrate
• enzymes catalyse specific reactions according to the shape of their active site

Question 11

How do enzymes work

Answer 11

• they break down a substrate into smaller molecules
• convert food into small soluble molecules to be absorbed into the bloodstream (digestive enzymes)
• builds new carbohydrates, lipids and proteins as well, catalyse reaction to join small molecules to make larger ones

Question 12

What are enzymes made out of?

Answer 12

Proteins, folded into a ball-like shape
(held together by chemical bonds)

Question 13

What can cause an enzyme to become denatured?

Answer 13

extreme temperature, pH can change the active site’s shape and cause the enzyme to no longer fit the substrate. This means that the enzyme is denatured

Question 14

What is the effect of temperature on enzyme activity

Answer 14

• optimum temperature = 40 degrees (human enzymes
• works slowly in colder temperatures (less kinetic energy) while they denature and stop working entirely when it gets hotter (substrate can no longer fit into active site)

Question 15

What is the effect of pH on enzyme activity?

Answer 15

• each enzyme has an optimum pH where its activity is at its highest (stomach protease vs salivary amylase)
• at an extreme pH the enzyme will denature

Question 16

What does amylase break down starch into?

Answer 16

glucose

Question 17

What does protease break down protein into?

Answer 17

amino acids

Question 18

what does lipase break lipids (fat) into?

Answer 18

glycogen and fatty acids

Question 19

What does bile do?

Answer 19

it emulsifies fats and to form small droplets to increase the surface area and to neutralise the hydrochloric acid in the partly digested food coming from the stomach

Question 20

What does the Benedict’s solution test for and how does it test it?

Answer 20

sugar and you mix the food with a few cm^3 of Benedict’s solution and heat it. it should start as blue and if it is positive it should turn into anorange red colour

Question 21

What does the iodine solution test for and how does it test for it?

Answer 21

• starch and you add a few drops of iodine solution into the food
• it should start as an orange brown colour and turn into a blue-black solution

Question 22

What does the biuret reagent test for and how does it test it?

Answer 22

• protein, you mix the food with a few cm^3 of reagent
• it should turn from blue to purple if it is positive

Question 23

What does the ethanol test for and how does it test for it?

Answer 23

• lipids and you shake the food with ethanol and you pour it into water
• it starts as clear and if it is positive an emulsion forms as a cloudy white layer

Question 24

Why are water baths used for the Benedict’s test

Answer 24

to maintain a constant temperature

Question 25

How does continuous sampling measure the time taken for amylase to digest a starch solution at different pHs.

Answer 25

• Timer starts when amylase and starch solutions are added together
• idodine reagent is used to test for starch every 30s (positive result will show blue black colour instead of orange brown)
• the time taken for the starch to be digested is recorded

Question 26

What does the immune system do?

Answer 26

desetroys pathogens inside the body and defends against disease

Question 27

How do phagocytes do their job

Answer 27

• detects and engulf pathogens
• extends cell membrane to surround pathogen and is taken into the cytoplasm
• enzymes in the cytoplasm destroy it

Question 28

How do lymphocytes do their job?

Answer 28

• they target specific pathogens
• pathogens have antigens (proteins on surface) and lymphocytes can detect these to produce the right type of antibody
• antibodies bind to the pathogen and make it harmless
• phagocytes can engulf and destroy pathogens
• lymphocytes can also produce antitoxins that neutralise the toxins made by the antigen
• some lymphocytes remain after an infection as memory cells and provide immunity

Question 29

How does vaccination prevent illness

Answer 29

• introduct a small amount of dead or inactive form of the pathogen to the body (mRNA vaccines give instructions to cells to make a protein antigen found on the pathogen)
• stimulates the white blood cells (lymphocytes) to product antibodies specific to this antigen
• memory cells remain in the body
• the white blood cells react quickly when exposed to the diease and they produce large amounts of the correct antibodies and destroy the pathogen quickly

Question 30

How do vaccines prevent the spread of illness

Answer 30

• most people are immune (herd immunity) so they don’t get ill when they get exposed to the disease
• less people who can pass it on
• less vulnerable/ unvaccinated people get exposed to the pathogen