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Biology AS Unit 2 - Organisms And Biodiversity > Topic 2 - Gaseous Exchange > Flashcards

Topic 2 - Gaseous Exchange Flashcards

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1
Q

What must the surface over which gas exchange takes place be

A

Permeable to oxygen and carbon dioxide

Moist, since gases must dissolve in water before diffusing into tissue cells

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2
Q

What is Ficks Law

A

Surface area x difference in concentration
Rate of diffusion = ——————————————————————-
Length of diffusion pathway

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3
Q

According to Fick’s Law, how is gas exchange increased

A

The exchange surface has a large surface area
There is a big difference in the concentration of gases on each side of the surface
The exchange surface is thin, with a short diffusion distance

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4
Q

What are the 2 processes in flowering plants that involve gas exchange

A

Respiration and photosynthesis

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5
Q

Where and when does Respiration take place

A

Where - in all times

When - all the time

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6
Q

Where and when does Photosynthesis take place

A

Where - in green tissues

When - only during the daylight hours

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7
Q

When does Maximum photosynthesis occur

A

When the light intensity is highest

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8
Q

What is the compensation point

A

The time of day when the rate of photosynthesis equals the rate of respiration, therefore the next exchange of oxygen is 0

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9
Q

What can increase the surface area-to-volume ratio in plants

A

The root hairs in epidermal cells

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10
Q

In plants, where does diffusion of respiratory gases take place

A

Through the cell wall and cell membrane of root hairs

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11
Q

Where are the most active cells in a plant cell

A

Those under the surface

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12
Q

In a stems outer covering, what is provided to increase diffusion

A

There are small pores to allow oxygen in and carbon dioxide out

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13
Q

Why do large plants lack specialised respiratory surfaces

A

They lack tissues with a high energy demand and so have low respiration rates

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14
Q

What is the major photosynthetic organ in a flowering plant

A

The leaf

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15
Q

Why do leaves need specialised gas exchange surfaces

A

A high rate of photosynthesis is generated

The concentration of carbon dioxide in air is low

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16
Q

Give the path of gaseous exchange, from Carbon Dioxide to Oxygen, in a leaf

A

Carbon dioxide is taken in by the opening of the stomata, by guard cells
The carbon dioxide is then diffused into the air space system in the spongy mesophyll
The spongy mesophyll cells then absorb the carbon dioxide, and is exchanged with oxygen
Oxygen produced is then diffused out the mesophyll cells into the air spaces and out through the stomata

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17
Q

What are some adaptations of hydrophytes in aquatic flowering plants that facilitates the uptake and movement of oxygen and carbon dioxide

A

Air spaces in the stem, so that it’s easier for oxygen to diffuse to all tissues, including the root
Air spaces in the leaf, so that it’s easier for diffusion of gases and aids the flotation of the leaf
Stoma on the upper epidermis, which allows gas exchange without the leaf becoming flooded, transpirational loss of water is not a problem

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18
Q

What is the difference between the inside of an animal cell and the outside, in terms of Carbon Dioxide and oxygen concentration

A

Outside- low CO2 concentration, high O2 concentration

Inside - high CO2 concentration, low O2 concentration

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19
Q

What are the 4 stages of movement of oxygen to cells, and of carbon dioxide out in mammals

A

Diffusion of gases between respiring tissues and blood
Transport of gases in blood
Diffusion of gases across the gas exchange surface between alveolar air and blood
Ventilation of the lungs with fresh air

20
Q

What is the trachea

A

The place where air enters or leaves the lungs

21
Q

What is the thorax

A

The place where the lungs are situated within

22
Q

What is the bronchi

A

What the trachea is branched into

23
Q

What are bronchioles

A

A fine series of cells within the bronchi that contain alveoli

24
Q

Where are alveoli located

A

In the bronchioles

25
Q

What is the structure and function of each alveolus

A

Each individual alveoli is tightly wrapped in blood capillaries and it is here that gas exchange takes place

26
Q

What occurs in the lungs when the volume of the thorax is increased

A

The pressure in the lungs is decreased, becoming lower than atmospheric pressure, so that air moves into the lungs

27
Q

What occurs in the lungs when the volume of the thorax is decreased

A

The pressure in the lungs is increased, becoming higher than atmospheric pressure so that air moves out of the lungs

28
Q

What is the difference between respiration and breathing

A

Respiration occurs in cells and is the release of energy from food to make ATP
Breathing refers to the movement of the ribs and diaphragm that causes air to enter and leave the lungs

29
Q

Describe the process of Inhalation

A

Muscular region of diaphragm contracts, external intercostal muscles contract
Diaphragm flattens and ribs move up and our
Volume of thorax increases
Pressure around lungs decreases
Pressure in alveoli decreases
Air enters lungs

30
Q

Describe the process of exhalation

A

Muscles of diaphragm and external intercostal muscles relax
Diaphragm returns to dome shape while ribs move down and in
Volume of thorax decreases
Pressure around lungs increases and recoil of elastic lungs
Pressure in alveoli increase
Air exits lungs

31
Q

What occurs in the lungs during forced exhalation

A

The volume of the thoracic cavity is further reduced by the contraction of the internal intercostal muscles depressing the rib cage

32
Q

How is a short diffusion distance maintain in lungs

A

The distance between alveolar air and the Erythrocytes are very short due to the squamous epithelial cells lining each of the alveolus
The Erythrocytes have to squeeze their way through the mare capillaries, ensuring that they are in contact with the endothelial wall, which further rescues the diffusion pathway

33
Q

How is a large surface area maintained in the lungs

A

There are 350 million alveoli situated in the lungs, totalling to a 70m2 surface area

34
Q

How is a steep concentration gradient maintained in the lungs

A

The ventilation of lungs and blood flow through pulmonary capillaries

35
Q

What are septal cells, and what are their function

A

Surfactant-secreting cells, they produce a detergent-like substance that reduces surface tension in the fluid coating the alveoli, and without which the alveoli would collapse due to cohesive forces between the water molecules lining the air sacs

36
Q

What are the role of macrophages in the lungs

A

They protect the lungs from a broad spectrum of microbes and particles by ingesting them through phagocytosis

37
Q

What is the role of the elastic fibres that are associated with the alveolar wall

A

They help to force air out during exhalation

38
Q

What does Tar do in the lungs

A

It brings about an inflammatory response in which airways narrow and excessive amounts of mucus are produced

39
Q

What is Tar

A

The collection of thousands of toxic substances found in tobacco smoke

40
Q

What causes the build up of mucus and pathogens in the lungs

A

Tar paralyses the cilia that sweep mucus and bacteria away from the lungs

41
Q

What are symptoms of pathogen and mucus build up

A

Phlegm production, breathlessness and coughing

42
Q

What is Emphysema

A

The inflammatory response to smoke inhalation which leads to the breakdown of the alveolar walls

43
Q

How does Emphysema affect Gas exchange

A

It reduces the area available for gas exchange so it becomes difficult to get enough oxygen. There is also a loss of elastic fibres in the alveolar walls

44
Q

What are carcinogens

A

Substances in tobacco smoke that can induce cancer

45
Q

How does Carcinogens damage DNA

A

They can damage DNA in the cells lining the bronchial tubes. Cells with DNA damage may divide in a modified and uncontrolled way, producing a mass of unspecialised cells known as a tumour

Biology AS Unit 2 - Organisms And Biodiversity (6 decks)

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