Transport In Animals

Question 1

Path of air in mammals

Answer 1

Trachea - bronchi - bronchioles - alveoli

Question 2

Alveoli adaptions

Answer 2

Large surface area provided by shape

Fluid lining allows gases to diffuse

Two cell layers thick - (endothelial capillary, epithelial alveolar )

Question 3

Inspiration

Answer 3

• External intercostal muscles contact
  Pulls ribcage up and out
• diaphragm muscles contract
  Pulls diaphragm down flat
• volume of thoracic cavity increases
• pressure decreases below atmospheric in lungs
• air drawn in

Question 4

Expiration

Answer 4

• External intercostal muscles relax
  Ribcage pulled down and in
• diaphragm muscles relax
  Diaphragm returns to dome shape
• volume of thoracic cavity decreases
• pressure increases above atmospheric
• elastic recoil forces air out

Question 5

Path of air in insects

Answer 5

Trachea - tracheoles - cells

Question 6

Adaptations for gas exchange in fish

Answer 6

Large surface area - provided by lots of gill filaments covered in lamellae

Short diffusion pathway - 2 cells thick endothelial capillary and epithelial lamellae

Countercurrent system - blood and water flow in opposite directions ensures blood meets water with a higher concentration of oxygen to concentration gradient is established along the entire lamellae

Question 7

Effect of CO2 on insects

Answer 7

CO2 levels rise due to respiration
Spiracles open wider
Increase rate of diffusion

During rest spiracles close to reduce water loss via evaporation

Question 8

Increased activity in insects

Answer 8

Leads to build up of lactic acid in cells from anaerobic respiration
Lowers water potential of cells
Water in tracheoles moves into cells by osmosis
Enables more air into tracheoles increasing rate of oxygen diffusion

Question 9

Where is endopeptidase found

Answer 9

The stomach

Question 10

Where does exopeptidase come from

Answer 10

The pancreas

Question 11

Endopeptidase function

Answer 11

Hydrolyses internal peptide bonds between amino acids

Question 12

Exopeptidase function

Answer 12

Hydrolyses peptide bonds at either end of a polypeptide

Question 13

Dipeptidase function

Answer 13

Hydrolyses dipeptides into two single amino acids

Question 14

Where is dipeptidase found

Answer 14

Microvilli of epithelial cells in the ileum

Question 15

Adaptations of ileum

Answer 15

Large surface area - long in length contains many villi and microvilli

High diffusion gradient - villi contain capillaries absorb monosaccharides, lacteals absorb digested lipids

Short diffusion pathway - each villi is one epithelial cell thick

Lots of mitochondria - ATP for active transport

Carrier and channel proteins - for absorption of specific molecules

Question 16

Absorption of lipids

Answer 16

• Bile salts emulsify lipid droplets
• Bile salts, fatty acids, and monoglycerides combine and form micelles
• Micelles break down next to epithelial cell releasing fatty acids and monoglycerides
• Fatty acids, monoglycerides and glycerol recombine in smooth endoplasmic reticulum
• triglyceride is formed and packaged in the Golgi body
• Forms Chylomicrons which are absorbed into lacteals

Question 17

Co transport (glucose)

Answer 17

• Na+ is actively transported out of the epithelial cell, concentration gradient is established
• Na+ can now diffuse in to the epithelial cell from the lumen of intestine
• glucose moves with them through carrier proteins
• glucose moves out the cell to the capillary by facilitated diffusion

Question 18

Path of blood

Answer 18

Body - vena cava - right atrium - right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium - left ventricle - aorta - body

Question 19

What happens when the atrium contracts

Answer 19

• Volume decreases and blood pressure increases
• Ventricle relaxed blood pressure is low
• pressure gradient from atria to ventricles
• forces atrioventricular valve open
• blood moves from atria to ventricle

Question 20

What happens when the ventricle contracts

Answer 20

• volume decreases and blood pressure increases
• atrioventricular valve forced closed preventing backflow of blood into the atria
• blood pressure in ventricles greater than in arteries
• semi lunar valve forced open
• blood flows from ventricles to arteries

Question 21

Cardiac output

Answer 21

Stroke volume x heart rate

Question 22

Arteriole capillary end

Answer 22

High hydrostatic pressure due to heart contraction
Hydrostatic pressure greater than osmotic pressure
Fluid and small molecules forced out
Forms tissue fluid
Large molecules remain in capillary lowering water potential
Water moves in via osmosis

Question 23

Venous capillary end

Answer 23

Low Hydrostatic pressure due to frictional resistance
Osmotic pressure is greater than hydrostatic pressure
Water from tissues fluid reabsorbed

Question 24

Haemoglobin

Answer 24

4 haem units
Each unit combines with one Oxygen
High affinity for oxygen at high partial pressure in lungs - O2 loaded
In tissues low partial pressure affinity decreases - O2 unloaded

Question 25

Explain the S shape of the dissociation curve

Answer 25

One molecule of oxygen binds to 1 of 4 haem units Causes change in tertiary structure of other haem units Increases their affinity for Oxygen Allows second oxygen to bind more easily

Question 26

Xerophyte adaptations

Answer 26

- Thick cuticle Long diffusion pathway reduces rate of evaporation - Hairs Trap still air reducing water potential gradient - SA:V Reduces surface area for water loss - Stomata Reduce exposure to air currents, traps air reducing water potential gradient - Rolled leaves Trap layers of still air reducing water potential gradient

Question 27

Xylem structure

Answer 27

Dead tissue - no cell content Hollow tubes - minimal resistance to flow of water and ions Cell wall strengthened by lignin - provides support and rigidity Transpiration stream - transports water and ions from roots to leaves

Question 28

Cohesion Tension

Answer 28

- Solar heat energy causes evaporation of water from leaves - Water moves from cell to cell across the leaf via osmosis - Water drawn from xylem causing tension - water column maintained by cohesive (attraction of water molecules to each other) and adhesive (attraction of water to xylem) forces - Upward movement of water maintains water potential gradient

Question 29

Transport in phloem

Answer 29

Sucrose actively transported into sieve tube by companion cell Water potential un sieve decreases Water from xylem moves un via osmosis High hydrostatic pressure un sieve In sink - sugar used for respiration Sucrose transported from sieve to sink Water potential in sieve increases Hydrostatic pressure in sink decreases