Unit 2 (2.3)

Question 1

Vascular systems of earthworms

Answer 1

Vascularisation, closed circulatory system and pumps, carriage of respiratory gases in blood

Question 2

Vascular systems of mammals

Answer 2

Double circulatory systems

Question 2

Vascular systems of fish

Answer 2

Single circulatory system

Question 3

Vascular systems of Insects

Answer 3

Open circulatory system, dorsal tube-shaped heart, lack of respiratory gases in blood

Question 4

What is a double circulatory system?

Answer 4

Circulatory system in which blood flows twice in two circuits, blood pumped from heart to lungs, returns to heart, pumped around body and returns to heart again.

Question 4

What is a single circulatory system?

Answer 4

Circulatory system where blood travels through heart once in one circuit, blood flows through the heart and is pumped around the body before returning to heart.

Question 5

Why is cardiac muscle describes as myogenic?

Answer 5

It initiates its own contraction without outside stimulation from nervous impulses.

Question 5

Four chambers of mammalian heart

Answer 5

Left Atrium
Right Atrium
Left Ventricle
Right Ventricle

Question 6

Five types of blood vessel

Answer 6

Arteries
Arterioles
Capillaries
Venules
Veins

Question 6

Structures of mammalian heart

Answer 6

Left atrium
Right ventricle
Bicuspid valve
tricuspid valve
Pulmonary vein
Vena cava
Semi-lunar valve
Aorta
Pulmonary artery

Question 7

What is the cardiac cycle?

Answer 7

The sequence of events involved in one complete contraction and relaxion of the heart

Three stages, atrial systole, ventricular systole and diastole

Question 8

What is plasma?

Answer 8

Main component of the blood (yellow liquid) that carries red blood cells

Contains proteins, nutrients, mineral ions, hormones, dissolved gasses, and waste.

Question 9

How does partial pressure of oxygen affect oxygen-haemoglobin binding?

Answer 9

Haemoglobin has variable affinity for oxygen depending on the partial pressure of oxygen, p(O2)

At high p(O2) oxygen associates for form oxyhaemoglobin
At low p(O2) oxygen dissociates to form deoxyhaemoglobin

Question 9

Role of haemoglobin

Answer 9

Present in red blood cells. Oxygen molecules bind to the haem groups and are carried around the body, then released where they are needed in respiring tissues.

Question 10

Why is the higher affinity of fetal haemoglobin important?

Answer 10

Enables the fetus to obtain oxygen from the mothers blood

Question 10

Why does fetal haemoglobin differ form adult haemoglobin?

Answer 10

Higher affinity for oxygen than adult haemoglobin due to the presence of two different subunits that allow oxygen to bind more readily .

Question 11

Compare the dissociation curves of adult and fetal haemoglobin

Answer 11

Fetal haemoglobin dissociation to the left. At the same partial pressure, % oxygen saturation is greater due to fetal haemoglobin having a higher affinity.

Question 12

What is the chloride shift?

Answer 12

Process by which chloride ions move into the erythrocytes in exchange for hydrogen carbonate ions which diffuse out of the erythrocytes.
One to one exchange

Question 13

Why is chloride shift important?

Answer 13

It maintains the electrochemical equilibrium inside the cell

Question 14

What is the Bohr effect?

Answer 14

The loss of affinity of haemoglobin for oxygen as the partial pressure of carbon dioxide increases.

Question 15

What is tissue fluid?

Answer 15

Fluid that surrounds the cells of animals
Same composition as plasma but does not contain red blood cells or plasma proteins.

Question 16

How is fluid tissue formed?

Answer 16

Blood pumped through increasingly smaller vessels, hydrostatic pressure is greater than oncotic pressure, fluid moves out of the capillaries. Then exchanges substances with the cells.

Question 17

Hydrostatic pressure

Answer 17

Higher at arterial end of capillary than venous end.

Question 18

Oncotic pressure

Answer 18

Changing water potential of the capillaries as water moves out, induced by proteins in the plasma.

Question 19

Structure of the dicotyledon root

Answer 19

Xylem arranged in x shape to provide resistance against force. Phloem found as patches between the arms. Surrounded by endodermis, aiding water passage.

Question 19

Which structure in plants is adapted for the uptake of root water and minerals?

Answer 19

Root hair cells

Question 20

Structure and function of endodermis

Answer 20

Innermost layer of the cortex of a dicot root Impregnated with suberin which forms the casparian strip Endodermal cells actively transport mineral ions into the xylem

Question 20

Three pathways which water moves through the root

Answer 20

Apoplast pathway Symplast pathway Vacuolar pathway

Question 21

Describe the symplast pathway

Answer 21

Water enters cytoplasm through the plasma membrane and moves between adjacent cells via, plasmodesma. Water diffuses down its water potential gradient by osmosis.

Question 21

Describe the vacuolar pathway

Answer 21

Water enters the cytoplasm through the plasma membrane and moves vacuoles of adjacent cells. Water diffuses down it's water potential gradient by osmosis.

Question 22

What is the transpiration steam?

Answer 22

The flow of water from the roots to the leaves in plants, where it's lost by evaporation to the environment.

Question 22

Describe the apoplast pathway

Answer 22

Water moves through intercellular spaces between cellulose molecules in the cell wall. It diffuses down water potential gradient by osmosis.

Question 23

How does water move up the stem?

Answer 23

Root pressure Cohesion tension theory Capillarity

Question 24

Explain cohesion-tension theory

Answer 24

Water molecules form H bonds with each other, so they stick together Surface tension of water creates this sticking effect Therefore as water is lost it loses its transpiration, more is drawn up the stem from the roots

Question 25

Factors that affect rate of transpiration

Answer 25

Light Temperature Humidity Air movement

Question 26

How does light affect rate of transpiration

Answer 26

High light increases rate of photosynthesis, causing more stomata to open for gas exchange, increasing rate of transpiration.

Question 27

How does temperature affect rate of transpiration

Answer 27

Higher temperature increases , so does random motion and rate of evaporation, therefore increasing rate.

Question 28

How does humidity affect rate of transpiration

Answer 28

Water content of the air next to leaf is high, reduces concentration gradient, decreases rate of transpiration

Question 29

How does air movement affect rate of transpiration

Answer 29

Large amounts of air blow moist air away from the leaves, creating a steep concentration gradient. Increases rate.

Question 30

What are cytoplasmic strands

Answer 30

Small extensions of cytoplasm between adjacent sieves tube elements and companion cells.

Question 31

Function of cytoplasmic strands

Answer 31

Allow communication and exchange of materials between sieve and tube elements, and companion cells. Hold nucleus in place

Question 32

Define translocation

Answer 32

The movement of organic compounds in the phloem, from sources to sinks.