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Biology > B6 - Exchange > Flashcards

B6 - Exchange Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What happens as the surface area and volume of an organism increase?

A

The surface area : volume ratio decreases

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2
Q

What is metabolic rate?

A

The amount of energy expended by an organism in a given time

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3
Q

How can metabolic rate be measured?

A

Oxygen consumption
Carbon dioxide production
Heat production

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4
Q

What is the basal metabolic rate?

A

Metabolic rate of an organism at rest
Very low, as energy is only requires for vital organs

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5
Q

What does a large surface area allow?

A

max. absorption of nutrients and gases, and secretion of waste products

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6
Q

What does a small volume allow?

A

Short diffusion distances to organelles

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7
Q

How have larger, multicellular organisms adapted to having a low SA:V ratio?

A

Specialised cells, tissues, organs and systems

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8
Q

What do effective exchange surfaces have?

A

A large surface area → to maximise the rate of diffusion
Thin walls →Short diffusion distance
Good/rich blood supply → maintain a concentration gradient

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9
Q

What is the structure of fish gills?

A

Series of gills on each side of the head
A gill arch is attached to two stacks of filaments
Each filament contains rows of lamellae, which increases the surface area
Lamellae surface consists of a single layer of flattened cells that cover many capillaries

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10
Q

What is the counter current system in fish gills?

A

Blood flow in the capillaries flows in the perpendicular to the flow of water

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11
Q

What does the counter current system in fish gills allow?

A

This system ensure the concentration gradient is maintained along the whole length of the capillary
E.g., water with the lowest oxygen concentration will be found adjacent to the most deoxygenated blood → oxygen will diffuse INTO the blood (vice versa for carbon dioxide)

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12
Q

What is the structure of a trachea of an insect?

A

Rigid exoskeleton
Spiracle
Trachea
Tracheoles
Cells

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13
Q

What are the adaptations of a trachea of an insect?

A

Insects have a rigid exoskeleton that is impermeable to gases
Spiracle: opening in the exoskeleton that has valves - allows air to enter the insect, and flow into tracheae
Tracheae: tubes that lead to tracheoles
Highly branched tracheoles are in contact with cells (increases SA and short diffusion distance) - this is where gas exchange occurs

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14
Q

What is the structure of plant leaves?

A

Cuticle
Upper epidermis
Palisade mesophyll
Xylem and phloem
Spongy mesophyll
Lower epidermis
Guard cells and stomata

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15
Q

What are the adaptations of a plant leaf?

A

Guard cells become turgid, keeps the stoma open, allowing air flow into the leaf
Air spaces in the spongy mesophyll layer allow rapid diffusion of carbon dioxide
Carbon dioxide is used up in photosynthesis
Thinness of the plant & presence of stomata allows for a short diffusion pathway
Upper epidermis is transparent
Cuticle is impermeable

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16
Q

How do plants that live in areas of limited freshwater (xerophytic) reduce water loss?

A

Very few stomata
Sunken stomata
Hairs surrounding stomata
Needle-shaped or small leaves
Waxy cuticle

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17
Q

What are the adaptations of a cacti?

A

Their leaves have spines
Stems have a thick cuticle - stores & prevents water loss
Possesses shallow and deep roots - more access to water
Can expand to store more water

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18
Q

What is a negative of adaptations that reduce water loss?

A

Negatively affects gas exchange (and vice versa)
E.g.Terrestrial insects have a waterproof exoskeleton
(due to a waxy coating on the surface), so therefore have to haves spiracles & the tracheal system ensure all tissues and cells receive oxygen

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19
Q

What are adaptations of marram grass?

A

Leaves can roll up → reduces the exposure of surfaces to the wind & protects the stomata
The exposed surface has no stomata and a thick cuticle
The inner surface contains a large number of hairs
Both adaptations cause water vapour to be trapped near stomata → reduces the water potential gradient → less water is lost through evaporation

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20
Q

What is the order of the human gas exchange pathway?

A

Trachea
Bronchi (one in each lung)
Bronchioles
Alveoli (surrounded by many capillaries)

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21
Q

What are features of the trachea?

A

The epiglottis is present: a flap of cartilage that covers the trachea when we eat
Cartilage keeps the airways open, muscle & elastic layers allow for flexibility
Ciliated, gland secreting cells trap bacteria & dust particles, and ‘waft’ them away from the lungs

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22
Q

What contains more muscles, the bronchi or the smaller bronchioles?

A

Bronchi & large bronchioles = contain cartilage, muscle & elastic fibres

Smaller bronchioles = smaller muscle & elastic fibres (so can expand and contract easily during ventilation)

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23
Q

What are the features of the alveolar epithelium (the surface of alveoli)?

A

Covered with a network of blood capillaries
Alveolar wall cells & capillary walls cells from a very thin barrier between air in the alveoli, and the blood
A short diffusion distance for oxygen & carbon dioxide exchange
Moist surface
A concentration gradient is maintained by ventilation and the continuous flow of blood

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24
Q

What occurs during inhalation?

A

External intercostal muscles contract
Ribcage moves up and out
Diaphragm contracts and flattens
Volume of thorax increases
Pressure inside thorax decreases
Air is drawn in (down a pressure gradient)

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25
Q

What occurs during inhalation when exercising?

A

Diaphragm flattens AND the external intercostal muscles contract → FORCED inhalation

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26
Q

What occurs during exhalation?

A

External intercostal muscles relax
Ribcage moves down and in
Diaphragm relaxes and becomes dome-shaped
Volume of thorax decreases
Pressure inside thorax increases
Air is forced out

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27
Q

What occurs during exhalation when exercising?

A

The internal intercostal muscles contract → ribs are pulled down and back → FORCED exhalation

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28
Q

How do you work out Pulmonary Ventilation Rate (PVR)?

A

PVR = tidal volume x breathing rate

29
Q

How does lung cancer occur?

A

Mutations occur in the oncogenes or tumour-suppressor genes of the bronchial epithelial cells
Uncontrolled mitosis → mass of cells develop in the lumen of the airways
Tumour grows & develops its own blood supply

30
Q

What are symptoms of lung cancer?

A

Coughing up blood
Persistent cough
back/shoulder pain
Sudden weight loss

31
Q

How does Chronic obstructive pulmonary disease (COPD) occur?

A

Goblet cells become enlarged → produce more mucus
Destroys the cilia in the trachea → excess mucus blocks narrow bronchioles → coughing, scar tissue, infection
Alveolar walls are destroyed by the immune system

32
Q

What are symptoms of Chronic obstructive pulmonary disease (COPD)?

A

Shortness of breath
Persistent cough
Chest tightness
Wheezing

33
Q

How does smoking effect the lungs?

A

Contains tar, nicotine and carbon monoxide
Effects on air passages: Tar destroys cilia → build up of mucus → bronchitis
Effects on alveoli: destroys the walls of the alveoli (reduces SA) → emphysema (blood carries less oxygen)

34
Q

What is a risk factor?

A

A factor that correlates with an increased chance of suffering from a condition / disease

35
Q

What is incidence of a disease?

A

Number of cases of a disease that occur within a group of people in a given time

36
Q

What are prospective studies?

A

Collecting data as it becomes available
Tends to be more accurate
Can be time-consuming

37
Q

What are retrospective studies?

A

Collecting data from the past
Unreliable
Results can be obtained more rapidly

38
Q

What should be taken into consideration when analysing data from studies on health risk factors?

A

Sample size
Individuals in the sample e.g., age, gender
Levels of exposure (to the risk factor)
Control group (should be a similar age, background)
Statistical significance = p value
The influence of other factors/variables (e.g., genetics, secondary exposure to smoking, exercise, etc)

39
Q

What is the normal significance level for biology?

A

5% significance level
P-value of 0.05

40
Q

What is a causal relationship?

A

Causality is an influence by which one event contributes to the production of another event

41
Q

What is the role of the digestive system?

A

Break down large insoluble molecules into smaller, soluble food molecules

42
Q

What is the role of the mouth in the digestive system?

A

Break down food, increase surface area to volume ratio
Carbohydrate digestion begins
Salivary glands - lubricates food

43
Q

What is the role of the oesophagus in the digestive system?

A

Hollow tube
Contractions of smooth muscle within the walls moves food down, towards the stomach (peristalsis)

44
Q

What is the role of the stomach in the digestive system?

A

Protein digestion begins
Glandular tissue: produces stomach acid which destroys microorganisms & lowers the pH & enzymes with low optimum pH (pepsin)
Muscular tissue: churns food, mixing it with enzymes and acids

45
Q

What is the role of the small intestine in the digestive system?

A

It is divided into three sections: duodenum, jejunum & the ileum
Smooth muscle within the walls contract rhythmically (peristalsis) to move food along
Carbohydrate, protein and lipid digestion occurs mainly in the duodenum
Carbohydrate, protein and lipid absorption occurs mainly in the jejunum and ileum (lots of villi cells)
Water absorption starts here

46
Q

What is the role of the large intestine in the digestive system?

A

Remaining water is absorbed here, as well as vitamins and minerals

47
Q

What is the role of the rectum in the digestive system?

A

Where faeces is stored

48
Q

What is the role of the liver in the digestive system?

A

produces bile, which helps break down fats
(Stored in the gall bladder)

49
Q

Where does the digestion of carbohydrates take place?

A

In the mouth and small intestine

50
Q

What hydrolyses starch into maltose?

A

Amylase

51
Q

Where is amylase produced?

A

Salivary glands, the pancreas and the small intestine

52
Q

What hydrolyses maltose into glucose?

A

Maltase
(found in cell-surface membranes of the epithelial cells lining the small intestine)

53
Q

Why are enzymes found in the cell-surface membrane of the epithelial cells in the small intestine?

A

Allows the absorption of monosaccharides into epithelial cells of the small intestine →pass them into the bloodstream

54
Q

What hydrolyses lactose?

A

Lactase

55
Q

What hydrolyses sucrose?

A

Sucrase

56
Q

In the stomach what are solid lipids are turned into?

A

A fatty liquid consisting of fat droplets

57
Q

What does bile do to fatty liquids?

A

Breaks the fatty droplets into smaller ones via emulsification → increases the SA of the fatty droplets for lipase to work

58
Q

Where does the digestion of lipids occur?

A

In the lumen of the small intestine

59
Q

What does lipase do?

A

Breaks down lipids (fats) to glycerol and fatty acids

60
Q

Where is lipase produced

A

Lipase enzymes are produced in the pancreas

61
Q

Where is lipase secreted?

A

Lipase is secreted into the small intestine

62
Q

What does endopeptidase do?

A

Hydrolyses peptide bonds within proteins, creating smaller sized protein “chunks”
Secreted along hydrochloric acid - pH of stomach is low & acidic
Protein chunks then move from the stomach, to the small intestine

63
Q

What does Exopeptidase do?

A

Released in the small intestine, hydrolyses peptide bonds at the ends of polypeptide chains to produce dipeptides

64
Q

What does Dipeptidases do?

A

Hydrolyses dipeptides into amino acids → amino acids released into the cytoplasm of the cell

65
Q

Where are the products of digestion absorbed?

A

Through the intestinal lining

66
Q

How are amino acids absorbed?

A

Amino acid + Na+ ion transported through a sodium-dependent amino acid carrier protein via facilitated diffusion, into the epithelial cell
Amino acids then move across through a amino acid channel protein, into the capillaries via facilitated diffusion
The concentration gradient of sodium is maintained by the active transport of Na+ ions out of the cell, into the blood by sodium-potassium pumps

67
Q

How are monosaccharides absorbed?

A

Glucose molecules + Na+ ions are transported through a sodium-dependent glucose carrier protein via facilitated diffusion, into the epithelial cell
Glucose then moves across through a glucose channel protein, into the capillaries via facilitated diffusion
The concentration gradient of sodium is maintained by the active transport of Na+ ions out of the cell, into the blood via sodium-potassium pumps

68
Q

What are micelles used for?

A

Monoglycerides and fatty acids associated with phospholipids and bile salts → form micelles (very small droplets) - aid in transport, as they are more soluble in water

69
Q

How are lipids absorbed?

A

Micelles bring fatty acids/monoglycerides to cell of the iluem
Short fatty acid chains within the epithelial cells can move directly into the blood via diffusion
Longer chains are unable to do so → reform polar triglycerides in the smooth ER
Triglycerides then packed into chylomicrons
Chylomicrons then enter the blood via the lacteals (a lymph vessel) via exocytosis

Biology (17 decks)

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