Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology > Topic 3 > Flashcards

Topic 3 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is the relationship between the size of an organism or structure and its surface area to volume ratio?

A

As the size of an organism or structure increases, its surface area to volume ratio decreases.

This means that larger organisms have relatively less surface area compared to their volume,

which can limit the rate of exchange of substances like oxygen, nutrients, and waste products between the organism and its environment..

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is the surface area to volume ratio important for organisms?

A

The surface area to volume ratio is crucial because it influences the rate of exchange of materials

(e.g., oxygen, carbon dioxide, nutrients, and waste products) between the organism and its environment.

A higher ratio means more surface area relative to volume, facilitating efficient exchange,

which is particularly important for smaller organisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do larger organisms adapt to a reduced surface area to volume ratio?

A

Larger organisms adapt to a reduced surface area to volume ratio through changes in body shape and the development of specialized systems:

Flattened shapes: Such as flatworms or leaves, increase surface area without significantly increasing volume.

Internal transport systems: Such as circulatory and respiratory systems, help distribute substances efficiently throughout the organism.

Folding and branching structures: Such as alveoli in lungs, villi in intestines, and root hairs in plants, increase surface area for exchange.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give an example of a body shape adaptation that increases surface area.

A

An example is the flattened body shape of flatworms,

which increases their surface area relative to their volume,

allowing for more efficient diffusion of gases and nutrients directly across their body surface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some specialized systems in larger organisms that facilitate exchange?

A

Some specialized systems in larger organisms include:

Circulatory system: Transports blood, nutrients, oxygen, and waste products throughout the body (e.g., humans, animals).

Respiratory system: Facilitates gas exchange (e.g., lungs in mammals, gills in fish).

Digestive system: Enhances nutrient absorption through structures like villi in the intestines.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why do larger organisms need to develop internal transport systems?

A

Larger organisms need internal transport systems

because the decreased surface area to volume ratio limits the direct diffusion of substances across their surfaces.

Internal transport systems (like the circulatory system) ensure that all cells receive necessary nutrients and oxygen and that waste products are efficiently removed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How do alveoli in the lungs adapt to the reduced surface area to volume ratio in larger organisms?

A

Alveoli in the lungs increase the surface area available for gas exchange.

Their numerous tiny, balloon-like structures create a large total surface area,

which enhances the efficiency of oxygen and carbon dioxide exchange between the lungs and the bloodstream in larger organisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do villi in the intestines facilitate nutrient absorption in larger organisms?

A

Villi in the intestines are small, finger-like projections

that increase the surface area for nutrient absorption.

Their structure ensures that digested food has a large area to be absorbed into the bloodstream,

compensating for the decreased surface area to volume ratio in larger organisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the adaptations of gas exchange surfaces in single-celled organisms?

A

Single-celled organisms exchange gases directly across their body surface by diffusion.

Their large surface area relative to volume, thin cell membrane, and moist surface facilitate efficient gas exchange.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the tracheal system of an insect function in gas exchange?

A

Insects use a tracheal system consisting of tracheae, tracheoles, and spiracles.

Spiracles open to allow air in, tracheae transport air, and tracheoles deliver oxygen directly to cells.

This system minimizes water loss while maximizing gas exchange efficiency.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the gas exchange process in fish gills.

A

Fish gills have gill lamellae and filaments that increase surface area for gas exchange.

They use a counter-current exchange principle,

where water flows over gills in one direction and blood flows in the opposite direction,

maximizing oxygen absorption.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do leaves of dicotyledonous plants facilitate gas exchange?

A

Leaves of dicotyledonous plants have mesophyll cells with large surface areas and stomata that open to allow gas exchange.

Stomata can close to reduce water loss, balancing gas exchange and water conservation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the structural and functional compromises between gas exchange and water loss in terrestrial insects?

A

Terrestrial insects minimize water loss through the closing of spiracles and a waxy cuticle.

They also limit the time spiracles are open, reducing water loss while ensuring sufficient gas exchange.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do xerophytic plants balance gas exchange and water loss?

A

Xerophytic plants have adaptations
such as:

thick cuticles, - reduced evaporation

sunken stomata, - humid air is trapped reducing water potential gradient between inside leaf and humid trapped
air

reduced leaf surface area. - for transpiration

These features limit water loss while allowing gas exchange necessary for photosynthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the gross structure of the human gas exchange system.

A

The human gas exchange system includes the alveoli, bronchioles, bronchi, trachea, and lungs.

Air travels through the trachea, bronchi, and bronchioles to reach the alveoli, where gas exchange occurs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the essential features of the alveolar epithelium?

A

The alveolar epithelium is thin, moist, and has a large surface area to facilitate gas exchange.

It is lined with capillaries to ensure close proximity between air and blood for efficient oxygen and carbon dioxide exchange.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Explain the mechanism of breathing in humans.

A

Breathing involves the diaphragm and the antagonistic interaction between the external and internal intercostal muscles.

The diaphragm contracts and flattens, while external intercostal muscles contract to expand the thoracic cavity, reducing pressure and drawing air in.

Relaxation of these muscles and contraction of internal intercostals decrease the thoracic cavity volume, increasing pressure and expelling air.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does ventilation and gas exchange occur in the lungs?

A

Ventilation moves air in and out of the lungs through the process of inhalation and exhalation.

Gas exchange occurs in the alveoli, where oxygen diffuses into the blood and carbon dioxide diffuses out, driven by concentration gradients.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens to large biological molecules during digestion?

A

They are hydrolysed to smaller molecules that can be absorbed across cell membranes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which enzymes are involved in the digestion of carbohydrates in mammals?

A

Amylases and membrane-bound disaccharidases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the role of amylase in carbohydrate digestion?

A

Amylase hydrolyses glycosidic bonds between starch into maltose.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the function of membrane-bound disaccharidases?

A

They hydrolyse disaccharides into monosaccharides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which enzymes are involved in the digestion of lipids?

A

Lipases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do bile salts aid in lipid digestion?

A

They emulsify fats, increasing the surface area for lipase action.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which enzymes are involved in the digestion of proteins?

A

Endopeptidases, exopeptidases, and membrane-bound dipeptidases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the role of endopeptidases in protein digestion?

A

hydrolise peptide bonds within the protein molecule, creating smaller peptide chains.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What do exopeptidases do in protein digestion?

A

hydrolyse peptide bonds terminal amino acids from peptide chains, producing dipeptides or single amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the function of membrane-bound dipeptidases?

A

hydrolyse peptide bonds between dipeptides into individual amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How are the products of digestion absorbed by cells lining the ileum?

A

Through various mechanisms, including co-transport and micelles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe the co-transport mechanism for the absorption of amino acids and monosaccharides.

A

The active transport of sodium ions from the epithelial cell into the blood lowers the sodium ion concentration inside the cell and generates a sodium ion concentration gradient between the ileum and the epithelial cell

Sodium ions move into the cell from the ileum by facilitated diffusion, carrying glucose molecules along with them via a cotransport protein

The glucose concentration inside the epithelial cell increases, and glucose molecules enter the blood via facilitated diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the role of micelles in the absorption of lipids?

A

Micelles transport fatty acids and monoglycerides to the surface of epithelial cells for absorption

Monoglycerides and fatty acids are lipid soluble so diffuse directly into cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is haemoglobin and what’s its role?

A

Haemoglobin is a protein with a quaternary structure found in many different organisms.

It is responsible for the transport of oxygen in the blood.

33
Q

What is the role of haemoglobin and red blood cells in the transport of oxygen?

A

Haemoglobin in red blood cells binds to oxygen in the lungs,

transports it through the bloodstream, and releases it in tissues where it is needed.

34
Q

Describe the loading, transport, and unloading of oxygen by haemoglobin.

A

Oxygen binds to haemoglobin in the lungs (loading),

is transported through the bloodstream, and is released in tissues (unloading).

35
Q

What does the oxyhaemoglobin dissociation curve represent?

A

The curve shows the relationship between the partial pressure of oxygen and the saturation of haemoglobin with oxygen.

It illustrates how haemoglobin’s affinity for oxygen changes with different oxygen concentrations.

36
Q

Explain the cooperative nature of oxygen binding to haemoglobin.

A

The binding of one oxygen molecule to haemoglobin causes a conformational change that makes it easier for additional oxygen molecules to bind.

This is known as cooperative binding.

37
Q

What is the Bohr effect?

A

The Bohr effect describes how increased carbon dioxide concentration and decreased pH lower haemoglobin’s affinity for oxygen,

promoting oxygen release in tissues.

38
Q

How are animals adapted to their environments in terms of haemoglobin?

A

Animals possess different types of haemoglobin with varying oxygen transport properties to suit their specific environmental conditions.

39
Q

Describe the general pattern of blood circulation in a mammal.

A

Blood circulates from the heart to the lungs for oxygenation (via pulmonary arteries),

back to the heart (via pulmonary veins),

and then throughout the body (via systemic circulation).

Blood returns to the heart from the body via the venae cavae.

40
Q

What are the coronary arteries?

A

Coronary arteries supply oxygen-rich blood to the heart muscle itself.

41
Q

Name the major blood vessels entering and leaving the heart, lungs, and kidneys.

A

Heart: Venae cavae (entering), aorta (leaving)

Lungs: Pulmonary arteries (leaving), pulmonary veins (entering)

Kidneys: Renal arteries (entering), renal veins (leaving)

42
Q

Describe the gross structure of the human heart.

A

The human heart has four chambers: two atria and two ventricles.

It has valves that regulate blood flow and ensure unidirectional movement.

semi lunar and atrioventricular valves

43
Q

What changes occur during the cardiac cycle to maintain unidirectional blood flow?

A

Pressure and volume changes in the heart chambers cause valves to open and close,

ensuring blood flows in one direction from the atria to the ventricles and out to the body.

44
Q

How are arteries, arterioles, and veins structured in relation to their function?

A

Arteries have thick, elastic walls to handle high pressure from the heart.

Arterioles control blood flow to capillaries via smooth muscle.

Veins have thinner walls and valves to prevent backflow and assist return of blood to the heart.

45
Q

Describe the structure and function of capillaries.

A

Capillaries have thin walls to facilitate exchange of gases, nutrients, and waste between blood and tissues.

Capillary beds enhance this exchange due to their large surface area.

46
Q

What is tissue fluid and how is it formed and returned to the circulatory system?

A

Tissue fluid forms when there’s a high pressure at the start of the capillary

fluid is forced out of the capillary

due to the fluid loss, and increasing conc of proteins, the water pressure is lower at the venule end

so some water re-enters by osmosis

any excess fluid is drained into the lymphatic system which transports this excess fluid and dumps it back into the circulatory system

47
Q

How do the semi-lunar valves differ from the AV valves in their function?

A

Semi-lunar valves control blood flow from the ventricles into the arteries (pulmonary and aorta),

whereas AV valves control blood flow between the atria and ventricles

48
Q

how do semi lunar valves open

A

The pressure is higher in the ventricles compared to the atria,

which forces the atrioventricular valves closed and causes the semi-lunar valves to open.

49
Q

how do the atriaventricular valves open

A

as the volume decreases.

The pressure is higher in the atria compared to the ventricles and there is a pressure gradient across the atrioventricular valves.

These valves therefore open.

50
Q

formula for cardiac output

A

cardiac output = stroke volume x heart rate

51
Q

What is the function of xylem tissue in plants?

A

Xylem tissue transports water from the roots to the stems and leaves of plants.

52
Q

Describe the cohesion-tension theory of water transport in the xylem.

A
  1. Water lost from leaf because of transpiration / evaporation of water (molecules) / diffusion from mesophyll / leaf cells;
    OR
    Transpiration / evaporation / diffusion of water (molecules)through stomata / from leaves;
  2. Lowers water potential of mesophyll / leaf cells;
  3. Water pulled up xylem (creating tension);
  4. Water molecules cohere / ‘stick’ together by hydrogen bonds;
  5. (forming continuous) water column;
  6. Adhesion of water (molecules) to walls of xylem;
53
Q

What is the role of phloem tissue in plants?

A

Phloem tissue transports organic substances, such as sugars, amino acids, and hormones, throughout the plant.

54
Q

describe the mass flow hypothesis in the phloem

A
  1. in source, sucrose is actively transported into the phloem
  2. By companion cells;
  3. Lowers water potential of sieve cell / tube and water enters by
    In source / leaf sugars actively transported into phloem;
    osmosis;
  4. Increase in pressure causes mass movement (towards sink /
    root);
  5. Sugars used / converted in root for respiration for storage.
    Accept starch
55
Q

What are tracers and ringing experiments used for in plant biology?

A

Tracers, often radioactive isotopes, and ringing experiments (removing a ring of bark from a tree)

are used to investigate and demonstrate the mechanisms of transport in plants.

Tracers help trace the movement of substances, while ringing experiments can show the importance of phloem in transporting organic materials.

56
Q

How do tracers help in understanding plant transport mechanisms?

A

Tracers allow scientists to follow the movement of specific substances within the plant,

providing visual and measurable evidence of how and where materials are transported.

57
Q

what does a ringing experiment demonstrate about plant transport?

A

Ringing experiments, which involve removing a ring of bark and phloem from around a stem,

show that when phloem is removed, the transport of sugars is interrupted, demonstrating the essential role of phloem in translocation.

58
Q

How do ringing experiments provide evidence for the role of phloem in transport?

A

Ringing experiments involve removing a ring of bark (including the phloem) from a stem.

This interruption in phloem leads to the accumulation of sugars above the ring and a lack of sugar transport below it,

indicating phloem’s role in translocating organic substances.

59
Q

What evidence from tracer experiments supports the mass flow hypothesis?

A

Tracer experiments show that labeled substances move from source to sink regions within the phloem,

supporting the idea that substances are transported via pressure differences, as suggested by the mass flow hypothesis.

60
Q

What evidence from ringing experiments supports the mass flow hypothesis?

A

Ringing experiments demonstrate that when phloem is removed,

the downward movement of sugars is halted, causing accumulation above the ring and depletion below it,

which aligns with the mass flow hypothesis that phloem transports organic materials.

61
Q

What are some arguments against the mass flow hypothesis?

A

Arguments against the mass flow hypothesis include

observations that not all substances move at the same rate,

some substances move in different directions simultaneously,

and the energy requirements and role of active transport are not fully explained by the hypothesis.

62
Q

How do observations of varying transport rates challenge the mass flow hypothesis?

A

The mass flow hypothesis suggests a uniform flow driven by pressure differences,

but varying rates of substance movement suggest that additional mechanisms, possibly involving active transport, may be at play.

63
Q

How does the observation of bidirectional flow in phloem challenge the mass flow hypothesis?

A

The mass flow hypothesis predicts a unidirectional flow from source to sink,

but evidence of substances moving in both directions simultaneously suggests a more complex transport mechanism than mass flow alone.

64
Q

Explain three ways in which an insect’s tracheal system is adapted for efficient gas exchange

A
  1. Tracheoles have thin walls so short diffusion distance to cells;
  2. Highly branched/large number of tracheoles so short diffusion distance to cells;
  3. Highly branched/large number of tracheoles so large surface area (for gas exchange);
  4. Tracheae provide tubes full of air so fast diffusion (into insect tissues);
  5. Fluid in the end of the tracheoles that moves out
    (into tissues)
    during exercise SO faster diffusion through the air to the gas exchange surface;
    OR
    Fluid in the end of the tracheoles that moves out (into tissues) during exercise so larger surface area (for gas exchange);
  6. Body can be moved
    (by muscles)
    to move air
    so maintains diffusion/concentration gradient for oxygen/carbon dioxide;
65
Q

Describe the gross structure of the human gas exchange system and how we breathe
in and out. (6)

A
  1. Named structures – trachea, bronchi, bronchioles, alveoli;
  2. Above structures named in correct order
    OR
    Above structures labelled in correct positions on a diagram;
  3. Breathing in – diaphragm contracts and external intercostal muscles contract;
  4. (Causes) volume increase and pressure decrease in thoracic cavity (to below atmospheric, resulting in air moving in);
  5. Breathing out - Diaphragm relaxes and internal intercostal muscles contract;
  6. (Causes) volume decrease and pressure increase in thoracic cavity (to above atmospheric, resulting in air moving out);
66
Q

Use your knowledge of surface area to volume ratio to explain the higher metabolic rate of a mouse compared to a horse. [3 marks]

A

Mouse

  1. (Smaller so) larger surface area to volume ratio;
  2. More/faster heat loss (per gram/in relation to body size);
  3. (Faster rate of) respiration/metabolism releases heat;
67
Q

why do plants grown in soil with less water grow slowly (2)

A
  1. Stomata close;
  2. Less carbon dioxide (uptake) for less photosynthesis/glucose production;
68
Q

Describe the role of micelles in the absorption of fats into the cells lining the ileum.
[3 marks]

A
  1. Micelles include bile salts and fatty acids;
  2. Make the fatty acids (more) soluble in water;
  3. Bring/release/carry fatty acids to cell/lining (of the ileum);
  4. Maintain high(er) concentration of fatty acids to cell/lining (of the ileum);
  5. Fatty acids (absorbed) by diffusion;
69
Q

Explain how the counter-current principle allows efficient oxygen uptake in the
fish gas exchange system. (2)

A
  1. Blood and water flow in opposite directions;
  2. Diffusion/concentration gradient (maintained) along (length of) lamella/filament;
70
Q

Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake. (2)

A
  1. Large(r) organisms have a small(er) surface area:volume (ratio);
    OR
    Small(er) organisms have a large(r) surface area:volume (ratio);
  2. Overcomes long diffusion pathway
    OR
    Faster diffusion;
71
Q

Describe the complete digestion of starch by a mammal.
[4 marks]

A
  1. Hydrolysis;
  2. (Of) glycosidic bonds;
  3. (Starch) to maltose by amylase;
  4. (Maltose) to glucose by disaccharidase/maltase;
  5. Membrane-bound (disaccharidase/maltase);
72
Q

Describe the transport of carbohydrate in plants.
[5 marks]

A
  1. Sucrose actively transported into phloem (cell);
    OR
    Sucrose is co-transported/moved with H+ into phloem (cell);
  2. (By) companion/transfer cells;
  3. Lowers water potential (in phloem) and water enters (from xylem) by osmosis;
  4. ((Produces) high(er) (hydrostatic) pressure;
    OR
    (Produces hydrostatic) pressure gradient;
  5. Mass flow to respiring cells
    OR
    Mass flow to storage tissue/organ;
  6. Unloaded/removed (from phloem) by active transport;
73
Q

Explain the importance of the xylem being kept open as a continuous tube. [3marks]

A
  1. (Allows unbroken) water column
    OR
    (So) no barrier to (water) movement;
  2. Cohesion from H bonds between (all) water (molecules)
    OR
    Cohesion from (polar) attraction between (all)
    water (molecules);
  3. Evaporation/transpiration creates tension (in
    column)
    OR
    Water moves from xylem (into cells) creates tension
    OR
    (To) pull up water creates tension (in xylem);
74
Q

Explain the importance of one adaptation of the gas exchange surface in the tracheal
system of an insect.
[2 marks]

A

EITHER
1. Tracheole (wall) thin/one cell thick;

  1. (So) rapid diffusion (into cells)
    OR
    (So) short diffusion pathway/distance;

OR

  1. Tracheoles enter/supply tissues/muscle fibres;
  2. (So) diffusion direct into cells
    OR
    (So) short diffusion pathway/distance
    OR
    (So) rapid diffusion (into cells);
    OR
  3. Tracheoles are highly branched;
  4. (So) short diffusion distance/pathway
    OR
    (So) large surface area for (rapid) diffusion;
75
Q

The rate of digestion of proteins is greatest when both enzymes are present.
Suggest why.
[2 marks]

A
  1. Endopeptidases create more ends / increases surface area;
  2. For exopeptidase to act on / hydrolyse / digest;
76
Q

What is digestion?
[2 marks]

A
  1. Hydrolysis (of);
  2. (Large / insoluble substances) to small(er) / soluble substances;
77
Q

Explain why oxygen uptake is a measure of metabolic rate in organisms.
[1 mark]

A

Oxygen used in) respiration, which provides energy / ATP;
OR
(Oxygen is used in) respiration, which is a metabolic process / chemical reaction;

78
Q

Suggest one practical advantage of measuring the masses of frog eggs, tadpoles and
adults, compared with measuring their volumes.
[1 mark]

A

More accurate / less error (in measuring mass);
OR
Causes less distress / damage to animal (to measure mass);
OR
Easier / quicker (to find mass) because
irregular shapes;
OR
Fewer measurements / calculations;

79
Q
A

A Level Biology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions