Biology topic 4

Question 1

What is endocytosis

Answer 1

Cell extensions called pilli engulf material to form vesicles and enter the cytoplasm

Question 2

What is exocytosis?

Answer 2

The vesicle fuses with cell membrane and release contents from the cell.

Question 3

Role of exo/endocytosis

Answer 3

To move large molecules across the cell membrane

Question 4

Role of ATP in active transport

Answer 4

Binds to carrier protein to provide it with energy for protein to change shape and carry substances in and out of the cell

Question 5

How is ATP energy released

Answer 5

When ADP is phosphorylated to ATP, energy is generated. When ATP is hydrolysed the energy is released

Question 6

What happens to haemoglobin affinity for oxygen and saturation when partial pressure increases

Answer 6

Haemoglobins affinity for oxygen increases, saturation increases

Question 7

What happens to haemoglobin affinity for oxygen and saturation when partial pressure decreases

Answer 7

Haemoglobins affinity for oxygen decreases, saturation decreases

Question 8

What factors affect haemoglobins affinity for oxygen?

Answer 8

Partial pressure of oxygen and carbon dioxide

Question 9

What effect does increased partial pressure of CO2 have on haemogobins affinity for O2

Answer 9

Presence of CO2 causes haemo’s affinity for O2 to decrease
Oxygen released, dissociates from haemo to be used in repairing tissues (Bohr effect)

Question 10

How many polypeptide chains does haemoglobin contain?

Answer 10

4 polypeptide chains

Question 11

How many polypeptide chains does myoglobin contain?

Answer 11

1 polypeptide chain

Question 12

Function of haemoglobin

Answer 12

Transport oxygen

Question 13

Function of myoglobin

Answer 13

Store oxygen

Question 14

Dissociation curves S shape

Answer 14

Due to cooperative binding of O2
After one O2 molecule binds, the shape of haemoglobin changes making it easier for other oxygen molecules to bind (steep part)
As haemo becomes highly saturated, harder for oxygen to bind (graph plateaus)

Question 15

Bohr effect

Answer 15

Curve shifts to the right due to increased CO2
Lowers pH causing haemo to change shape
Reduces affinity for O2
Increased O2 unloading in respiring tissues used for respiration.

Question 16

Dissociation curve shifts to the left?

Answer 16

Increased affinity
Increased loading in the lungs at lower O2
Good for organisms at high altitude

Question 17

Dissociation curve shifts to the right

Answer 17

Decreased affinity
Increased unloading in respiring tissues
Good for organisms with high metabolic rate

Question 18

Definition of hydrostatic pressure

Answer 18

Residual pressure from the heartbeat
Higher at arterial end of capillary

Question 19

Definition of oncotic pressure

Answer 19

Movement of fluid out of capillaries due to hydrostatic pressure
Water potential of capillaries become more -ve

Question 20

Features of the xylem

Answer 20

Transport of water and minerals
Dead cells, long cylinders with open ends to form continuous columns
Pits- Allows water to move sideways
Lignin- Structure and flexibility to structure

Question 21

Features of the phloem

Answer 21

Living cells
Movements of nutrients to storage, organs, and growing parts
Sieve tube elements- Form tube to transport sugars
Companion cells- ATP production, for active processes
Cytoplasm linked by plasmodesmata- gaps between cell walls allowing flow between cells

Question 22

Symplast pathway (xylem)

Answer 22

Water moves through cytoplasm via plasmodesmata

Question 23

Apoplast pathway (xylem)

Answer 23

Water moves through cell walls and intercellular spaces that are permeable

Question 24

Affect of air movement on transpiration

Answer 24

Increased air movement- increased transpiration
Removes still air around leaf
Increases conc gradient and diffusion rate

Question 25

Affect of humidity on transpiration

Answer 25

Increased humidity- decreased transpiration
Decreases conc gradient and diffusion rate

Question 26

Affect of temperature on transpiration

Answer 26

Increase temp- increases random motion, increases rate of evaporation- increases rate of transpiration
Warmer air holds more water vapour

Question 27

Light intensity on transpiration

Answer 27

Increased light intensity- increased transpiration
Increases no of stomata open for gas exchange
Plateaus when all stomata open

Question 28

Mass flow hypothesis summary

Answer 28

1. Sugar loaded into sieve tubes via active transport
2. Lowers H2O potential, H2O to move in from xylem
3. Hydrostatic pressure cause sugars to move

Question 29

Function of plasma

Answer 29

Transport nutrients, hormones, excretory products etc
Transfer heat around body

Question 30

Function of erythrocytes

Answer 30

Red blood cells
Transport O2
Biconcave shape + lack of nucleus
Contain haemoglobin

Question 31

Different types of leukocytes

Answer 31

Leukocytes- White blood cells
Neutrophils- Phagocytosis
Basophils- Histamine, inflammatory/allergic rxn
Eosinophils- Parasites, allergic, inflammatory, immunity

Question 32

2 types of agranulocytes

Answer 32

Monocytes
Lymphocytes

Question 33

Blood clotting process

Answer 33

1. Platelets attach to exposed collagen fibres
2. Thromboplastin (protein) released from platelets. Trigger inactive prothrombin to active thrombin (enzyme)
   Ca2+ and vit K present
3. Thrombin catalyses conversion of soluble fibrinogen to insoluble fibrin
4. Fibrin- network of fibres traps contents to form blood clot.

Question 34

How is tissue fluid formed

Answer 34

Formed from blood plasma
Hydrostatic pressure, moves out of the capillaries

Question 35

Function of tissue fluid

Answer 35

Provides nutrients to cells
Removes waste products

Question 36

What happens to the tissue fluid not reabsorbed?

Answer 36

Enters lymphatic system
Prevents swelling due to water retention
Formed lymph —> removes waste products
Lymph returns to the subclavian vein