Digestion And Mass Transport

Question 1

What are the two types of digestion

Answer 1

physical
Chemical

Question 2

Explain physical digestion

Answer 2

Breakdown of food through mechanical movements in the body such as chewing to increase surface area for enzymes to work on

Question 3

Explain chemical digestion

Answer 3

Enzyme action via hydrolysis breaks down large insoluble molecules into smaller soluble ones

Question 4

What is the function of mouth and salivary glands in digestion

Answer 4

Teeth: physical digestion, mastication breaks up food creating large surface area for enzymes to act upon
Salivary glands: release amylase to hydrolyse starch into maltose

Question 5

Explain the function of the oesophagus in digestion

Answer 5

Uses muscle contractions to reduce volume and increase pressure to push food to back of mouth and down the oesophagus

Question 6

Explain the function of the stomach in digestion

Answer 6

Churns food- physical digestion
Releases peptidases for the digestion of proteins into amino acids
Produces HCl for destruction of microorganisms (mainly found in proteins so is used for meat mostly)

Question 7

What are the 3 types of peptidases

Answer 7

Exopeptidases
Endopeptidases
Dipeptidases

Question 8

What do exopeptidases do

Answer 8

Remove terminal amino acids (amino acids from the end of the polypeptide)

Question 9

What do endopeptidases do

Answer 9

Hydrolyse central central peptide bonds to produce shorter polypeptides

Question 10

What do dipeptidases do

Answer 10

Hydrolyse the peptide bond between 2 amino acids

Question 11

explain the function of the liver in digestion

Answer 11

The liver produces bile salts which are stored in the gall bladder, these emulsify lipids increasing the surface area for lipase to act upon, bile also neutralises acid

Question 12

explain the function of the pancreas in digestion

Answer 12

Releases ‘pancreratic juice’, a mixture of pancreatic amylase, protease, and lipase
also produces alkaline salts

Question 13

explain the function of the small intestine (ileum) in digestion

Answer 13

monomers of digestion are observed, wall is folded to form villi, each villus is coated with epithelial cells which have microvilli structures to increase surface area
ileum contains membrane bound disaccharides these digest maltose into glucose monomers

Question 14

explain the function of the large intestine in digestion

Answer 14

absorption of water via osmosis, contains many bacteria, faeces begins to form

Question 15

explain the function of the rectum and anus in digestion

Answer 15

rectum is where faeces is stored
anus is involved with egestion of the faeces

Question 16

explain the features for absorption in the ileum

Answer 16

1) Many villi which are coated with many microvilli increasing surface
2) The surface of epithelial cells have microvilli a single cell thick
3) Walls of the ileum are lines with muscle which contacts to move food inside the lumen maintaining a concentration gradient
4) each villus has good blood supply

Question 17

explain co transport of glucose/amino acids and sodium ions

Answer 17

Na+ ions are actively transported out of epithelial cells into the blood
Creates low concentration of Na+ in epithelial cells
Na+diffuses down gradient from the lumen of ileum into the epithelial cells
Glucose and amino acids are brought in with Na+ against their concentration gradient using cotransporter protein
Gluicose and amino acids then diffuse into blood by facilitated diffusion

Question 18

explain the process of lipid absorption

Answer 18

lipid droplets are emulsified by bile salts.
Lipases digest the triglyceride into 2 fatty acids and a monoglyceride which associate with bile salts forming micelles.
At the lining of the villi micelles dissasociate and release these products as they are non polar and lipid soluble and can diffuse across the membrane.
the monoglycerides and fatty acids are transported to ER to me recombined.
the triglycerides move to golgi where they are associated with cholesterol and lipoproteins to form chylomicrons
chylomicrons are exocytosed from cell

Question 19

Explain the structure of haemoglobin

Answer 19

Has a quaternary structure of 4 polypeptide chains (2 alpha 2 beta), each chain has a haem group containing a ferrous ion (Fe2+)

Question 20

Explain how many atoms and molecules of oxygen a haemoglobin molecule can carry

Answer 20

Each haem group can bind to an 02 molecule
4 molecules
8 atoms

Question 21

Organisms living in a low oxygen area have haemoglobin with low or high affinity

Answer 21

Low affinity so oxygen is readily released to respiring tissues

Question 22

What is a low affinity for oxygen

Answer 22

Haemoglobin that doesn’t bind to oxygen as readily

Question 23

Oxygen combining with haemoglobin results in

Answer 23

Oxyhaemoglobin

Question 24

What is the role of haemoglobin

Answer 24

Associate with oxygen at gas exchange surfaces
Dissociate oxygen readily to respiring tissues

Question 25

How come haemoglobin perform its role

Answer 25

Can change its affinity for oxygen in certain conditions

Question 26

How is oxygen loaded transported and unloaded in the blood

Answer 26

1. haemoglobin carries oxygen/ has high affinity for oxygen 2. loading/ uptake in the lungs 3. at high partial pressure of oxygen 4. unloads/ dissociates/ releases oxygen at respiring cells/tissues 5. at low partial pressures of oxygen 6. unloading linked to higher CO2 concentration at respiring tissues

Question 27

How does a high partial pressure increase affinity for oxygen

Answer 27

Increases affinity

Question 28

What happens to haemoglobin after an oxygen binds

Answer 28

Changes the tertiary structure and opens up another region for oxygen to bind (positive cooperativity)

Question 29

How does carbon dioxide effect haemoglobins affinity

Answer 29

CO2 is released from respiring tissues and dissolves in the blood which produces carbonic acid. This lowers pH which changes the tertiary structure of haemoglobin. This decreases oxygen affinity and oxygen is released to respiring tissues

Question 30

What does the shape of an oxygen dissociation curve show

Answer 30

More to the left: Haemoglobin has a higher affinity for oxygen at low partial pressures and so binds to it more readily More to the right: Haemoglobin has a lower affinity for oxygen at higher partial pressures and so dissociates more readily

Question 31

What is the Bohr effect

Answer 31

a decrease in the amount of oxygen associated with hemoglobin and other respiratory compounds in response to a higher partial pressure of co2 and so the curve shifts to the right

Question 32

How does car

Question 33

How is haemoglobin adapted to small animals

Answer 33

Small animals have a larger surface area to volume ratio and so they lose heat more easily they therefore have a higher metabolic rate to produce more heat to counter act the loss. They therefore require a higher oxygen concentration and so haemoglobin is adapted to have a lower affinity for oxygen at any given partial pressure allowing dissociation to occur more readily

Question 34

How is fetal haemoglobin adapted

Answer 34

The foetus gets oxygen form the mother through the placenta. Feral haemoglobin is adapted to have a higher affinity for oxygen than the mother and this allows the fetal haemoglobin to bind to oxygen at lower oxygen partial pressures

Question 35

Higher partial pressure means ______ affinity

Answer 35

High

Question 36

Where does haemoglobin bind

Answer 36

The lungs

Question 37

what are circulatory systems needed for

Answer 37

-Supply substances over a large distance -Larger animals -Metabolically active organisms

Question 38

what are the specialised features of transport systems

Answer 38

-Suitable meduim (most are water based as it is a solvent) -Mechanism of medium transport -Closed tubular systems (so reaches all cells) -Mass transport (moving medium in bulk)

Question 39

how do animals control these systems

Answer 39

muscular contractions and active processes

Question 40

how do plants control these systems

Answer 40

passive processes such as evaporation

Question 41

what is needed for mass flow to work

Answer 41

-Must be unidirectional (one direction) -Have mechanisms to control and change the mass flow to suit the needs of the organism -Have mechanisms to support mass flow of specific mediums

Question 42

how does the human body achieve whats needed for mass flow

Answer 42

1) Valves control unidirectional flow of blood 2) Muscular tissue in the blood vessels allow for constriction and dilation, changing pressure and thus flow 3) Intercostal muscle in thorax contracts and relaxes to change pressure

Question 43

what is an open circulatory system

Answer 43

the medium transporting the nutrients around the body is not always contained in vessles and may directly make contact with tissues (small organisms)

Question 44

what is a closed circulatory system

Answer 44

the medium transporting the nutrients is contained in vessels

Question 45

what is a single system

Answer 45

involves transport medium only passing through once

Question 46

what is a double system

Answer 46

involves transport medium passing through the heart twice