Exchanges of Substances with the Environment

Category: Exchanges of Substances with the Environment

In this unit we get our first taste of Physiology in A Level biology - and start to look at how the body functions and systems with-in organisms.

We pick up from GCSE looking at Surface Area to Volume ratio, and adaptations of this that allow organisms to survive; for example,  at different temperatures. Surface area also links into the gaseous exchange systems in humans, insects, fish and plants. Understanding of the human gaseous exchange system also requires understanding and interpreting data on diseases which affect it.

Mass Transport means the movement of substances around a multicellular organism. In many organisms this takes the form of a circulatory system. In this unit, we look at Haemoglobin, and  oxygen dissociation curves. You need to be able to describe the effect of partial pressure of oxygen on haemogoblin’s affinity for oxygen. You also need to be able to describe the Bohr effect, and apply your knowledge to what may be unfamiliar species such as lugworms.

In terms of gross anatomy, at A level several major arteries such as the aorta, pulmonary and renal arteries need to be identified, and more importantly the structural differences between arteries, veins and capillaries. The structures of the heart also need to be identified, all be it in much the same level as higher GCSE. The cardiac cycle is extended from GCSE, looking at interpreting pressure changes , and calculating cardiac output and stroke volume. Cardiovascular disease data must be interpreted, including; atheroma, and thrombus formation.

Mass transport in plants has two separate routes:transpiration for water via xylem, and mass flow for organic substances via phloem.  Once again, GCSE is extended to looking at cohesion -tension in the xylem, and translocation via mass flow hypothesis in plants. In the Mass Flow  Hypothesis, changes in water potential caused by the formation of soluble substances (like glucose) cause pressure changes, which push the solutes towards ‘sinks’ where the solute concentration is lowered.

124

Surface Area to Volume Ratio and Adaptations to Exchange

1 / 20

The surface area in biology often refers roughly to how much skin an organism has, or how much cell membrane a cell has. Which of the following will have the biggest surface area, if they are all approximately the same length and width?

2 / 20

A Palisade cell is rectangular, and measures 100 µm by 40 µm. What is its surface area?

3 / 20

What is the volume of the same palisde cell measuring 100 µm by 40 µm?

4 / 20

What is the surface area to volume ratio of a palisade cell with a volume of 120,000 µm 3 and a surface area of 6500 µm2?

5 / 20

If we assume a spongy mesophyll cell is approximately a sphere. Using the formula 4 pi r 2 , what is its surface area if its diameter is 80 µm?

6 / 20

What is the volume of the same roughly spherical spongy mesophyll cell with a diameter of 80 µm, using the formula Volume=4/3 pi r 3?

7 / 20

What is the surface area to volume ratio of a spongy mesophyll cell with the surface area of 24,000 µm 2, and a volume of 110,000µm 3?

8 / 20

Is it important which way round the numbers go when writing a ratio?

9 / 20

Cresol red is an indicator which goes clear at a low pH. A plate of agar jelly with cresol red added was made, and two blocks were cut out. Block A measured 10mm x 10mm x 10mm. Block B measured 20mm x 7mm x 7mm. Are they a similar volume (within 5% difference)?

10 / 20

Cresol red is an indicator which goes clear at a low pH. A plate of agar jelly with cresol red added was made, and two blocks were cut out. Block A measured 10mm x 10mm x 10mm. Block B measured 20mm x 7mm x 7mm. Are the two agar blocks a similar surface area (within 5% difference)?

11 / 20

Cresol red is an indicator which goes clear at a low pH. A plate of agar jelly with cresol red added was made, and two blocks were cut out. Block A measured 10mm x 10mm x 10mm. Block B measured 20mm x 7mm x 7mm. Which one will decolourise quickest when placed in an acidic solution ?

12 / 20

Cresol red is an indicator which goes clear at a low pH. A plate of agar jelly with cresol red added was made, and two blocks were cut out. Block A measured 10mm x 10mm x 10mm. Block B measured 20mm x 7mm x 7mm. You have chosen one which will decolourise the quickest, why did you choose that block?

13 / 20

Why can single celled organisms exchange many substances by simple diffusion over the plasma membrane?

14 / 20

Multicellular organisms cannot absorb enough substances by diffusion. Why is this?

15 / 20

How have multicellular organisms adapted to not being able to absorb everything via diffusion over their surface?

16 / 20

Some animals are adapted to higher temperatures in their environment. Which of the following is an example of this ?

17 / 20

Some animals are adapted to a lower environmental temperature. Which of the following is an example of this?

18 / 20

Other than surface area to volume ratio, which is an example of a physiological adaptation, which allows an animal to live at colder temperatures?

19 / 20

Other than surface area to volume ratio, which is an example of a physiological adaptation, which allows an animal to live at hotter temperatures?

20 / 20

Which is an example of a behavioural adaptation which allows an animal to live at hotter temperatures?

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194

Human Gaseous Exchange & Lung Disease

1 / 25

Which letter represents the trachea?

2 / 25

Which two letters would be held open by C shaped cartilage rings?

3 / 25

Which letter represents the diaphragm?

4 / 25

Which term best describes breathing?

5 / 25

What shape is the diaphragm when it is contracted?

6 / 25

Which muscles are contracted when you inhale?

7 / 25

Which of the following is the correct sequence for inhalation?

8 / 25

True or False - Air moves into the lungs because the internal pressure in the lungs drops below the atmospheric pressure?

9 / 25

Which muscles contract when you exhale at rest?

10 / 25

Which muscles contract during forced expiration?

11 / 25

As oxygen diffuses from the alveolar air space into the blood, how many layers of cells does it pass over?

12 / 25

What is the correct term for the cells which make up the alveolar wall?

13 / 25

How is a concentration gradient maintained between the alveolar space and the blood?

14 / 25

What does Pulmonary Ventilation Rate (PVR) mean?

15 / 25

Pulmonary Ventilation Rate ( PVR) -= Tidal Volume x breathing rate. If someone take 60 breaths over 5 minutes, and takes in 230 cm3, what is their PVR?

16 / 25

Pulmonary Ventilation Rate ( PVR) -= Tidal Volume x breathing rate. If the breathing rate is 7, and the PVR is 1.4 dm3 min -1, what is the tidal volume?

17 / 25

If someone's PVR is 1.5dm3 min -1, and their tidal volume is 150 cm 3, how many breaths do they take in a minute?

18 / 25

Forced Expiratory Volume (FEV) is the maximum volume of air that can be breathed out in 1 second. What is the FEV for person B?

19 / 25

Why might the FEV be lower for person B?

20 / 25

Why would someone with Pulmonary Fibrosis have a reduced rate of oxygen diffusion?

21 / 25

Tuberculosis (TB) is caused by bacteria infecting the lungs, where amongst other effects it reduces tidal volume. What happens to the ventilation rate of sufferers?

22 / 25

Emphysema is caused by what?

23 / 25

What effect does emphysema have on the alveoli?

24 / 25

Sufferers of emphysema also have reduced elastin in the alveolar walls. What effect does this have on breathing?

25 / 25

What is 'Tidal Volume'?

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191

Fish, insect and Plant Gaseous Exchange

1 / 25

Why do some xerophytes have hairs over the stomatal pits?

2 / 25

Why do some xerophytes have their stomata in pits?

3 / 25

What is a xerophyte?

4 / 25

Why do the guard cells become 'curved' when they swell up?

5 / 25

How does water move into the guard cells?

6 / 25

Which term describes that guard cells when the plant has plenty of water available?

7 / 25

Why are there large gaps between the mesophyll cells ?

8 / 25

How is a concentration gradient maintained inside the leaf?

9 / 25

Which number represents a layer which is 2 or 3 times thicker in desert plants?

10 / 25

Which number represents cells that can control water loss?

11 / 25

Which number represents a stoma?

12 / 25

Which number represents the layer where gaseous exchange happens in plants?

13 / 25

What maintains the concentration gradients for gaseous exchange in the tracheoles?

14 / 25

Oxygen diffuses out of the tracheoles directly into what?

15 / 25

Which letter represents the part that can control water loss?

16 / 25

Which letter is the tracheae?

17 / 25

Which letter is the spiracles?

18 / 25

The diagram shows an insect respiratory system. Which letter represents the tracheoles?

19 / 25

Why does the blood flow in an opposite direction the the water?

20 / 25

The blood and water flow in opposite directions, what is this called?

21 / 25

What is the function of the lamellae?

22 / 25

Using the diagram, which part is a lamella?

23 / 25

Using the diagram, which part is a gill filament?

24 / 25

Many species of fish have developed a technique to allow a constant flow of oxygenated water over the gills, even when stationary. This is called Buccal Pumping, how does it work?

25 / 25

The Great White Shark and Black-tipped Reef Shark are two species which must keep swimming to stay alive. Why is this?

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181

Haemoglobin and Circulatory System

1 / 25

Haemoglobin is a quaternary protein, how many polypeptide chains make up a single molecule of haemoglobin?

2 / 25

Why is haemoglobin described as being 'Quaternary'?

3 / 25

What term describes the haem groups which contain iron?

4 / 25

How many oxygen molecules can each haem group carry?

5 / 25

What unit do we use to measure the concentration of oxygen in the tissue?

6 / 25

Where in a human, is the affinity of haemoglobin for oxygen the highest?

7 / 25

Where in a human, is the saturation of haemoglobin with oxygen the lowest?

8 / 25

On the graph, which letter shows where it is hardest for oxygen to associate?

9 / 25

If Carbon Dioxide concentration increases, which letter shows the direction the curve will shift?

10 / 25

What is it called, when Carbon Dioxide causes the dissociation curve to shift?

11 / 25

During the Bohr Effect, what happens to the affinity of haemoglobin for oxygen?

12 / 25

Why is it useful that the Bohr Effect reduces the percentage saturation of Haemoglobin with oxygen?

13 / 25

In which direction ( if any), would a curve be for humming bird haemoglobin?

14 / 25

In which direction ( if any), would a curve be for diving seal haemoglobin?

15 / 25

In which direction ( if any) , would the curve be for human foetal haemoglobin?

16 / 25

In the diagram of the human circulatory system, which letter represents the Vena Cava?

17 / 25

In the diagram of the human circulatory system, which letter represents the Pulmonary Vein?

18 / 25

What do we call the arteries which supply the heart muscle?

19 / 25

What do we call the arteries which supply the kidneys?

20 / 25

As blood moves away from the heart, it travels in which type of blood vessel?

21 / 25

Once blood leaves arteries, which type of blood vessel will it enter?

22 / 25

Which type of blood vessel has the widest lumen?

23 / 25

Which type of blood vessel has a folded endothelium?

24 / 25

Which type of blood vessel has the thickest muscular layer?

25 / 25

Capillaries are made only out of one layer of cells called endothelium. Why is this?

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124

Heart Structure and Heart Disease

1 / 25

Name the structures labelled A

2 / 25

Name the structures labelled B

3 / 25

When will the valves close?

4 / 25

One of the phases of the cardiac cycle is called Atrial Systole. During Atrial Systole, what is happening in the heart during this phase?

5 / 25

What happens to the heart during Diastole?

6 / 25

What happens during Ventricular Systole?

7 / 25

Cardiac Output ( CO) = Stroke Volume (SV) X Heart Rate ( HR). What is the cardiac output of an athlete with a SV of 95 cm3 , and a HR of 52 bpm?

8 / 25

What is the stroke volume of a patient if their cardiac output is 3500 cm3 min-1, and their heart rate is 70 bpm?

9 / 25

Which chamber do you think the green line represents?

10 / 25

Which chamber do you think the blue line represents?

11 / 25

What has happened at position A?

12 / 25

What has happened at position B?

13 / 25

What has happened at position C?

14 / 25

What has happened at position D?

15 / 25

Why are the Atrioventricular valves open at D?

16 / 25

What is Cardiovascular Disease?

 

17 / 25

What is an Atheroma?

18 / 25

What is a Thrombosis?

19 / 25

Which of the following IS NOT a way that smoking contributes to the risk of CVD?

20 / 25

Which of the following is a way a high salt content in your diet increases your risk of developing CVD?

21 / 25

Does this bar cart show a correlation between number of cigarettes smoked, and the risk of CVD?

22 / 25

This bar chart shows the risk of CVD with differing amounts of cigarettes smoked per day. Is there a significant difference in risk between smoking no cigarettes, and smoking 1 - 19 cigarettes a day?

23 / 25

Is there a significant difference between risk of CVD smoking -19 cigarettes a day and more than 20 cigarettes a day?

24 / 25

Does this chart show a causal relationship between Risk of CVD and smoking?

25 / 25

Why can we not state using this data, CVD is caused by smoking?

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89

Mass Transport in Plants

1 / 25

Xylem or Phloem ? - This type of cell is living, but with few organelles.

2 / 25

Xylem or Phloem ? - This type of cell is carries dissolved organic substances both up and down the plant

3 / 25

Xylem or Phloem ? - No end plates on these cells

4 / 25

What is transpiration the movement of?

5 / 25

Through which part does the water evaporate out of the leaf?

6 / 25

The evaporation of water molecules out of the leaf, 'pulls' the water molecules behind up. What is this 'pull' called ?

7 / 25

Water molecules stick together due to what type of bond?

8 / 25

What term is used to describe the 'sticking' together of water molecules?

9 / 25

Which of the following would decrease the rate of transpiration?

10 / 25

How does an increase in wind speed, increase the rate of transpiration?

11 / 25

What piece of equipment is used to measure transpiration ?

12 / 25

Which direction will the bubble move?

13 / 25

What is the tap and water reservoir above it for?

14 / 25

How do you calculate the rate of water transpired by the plant?

15 / 25

Which would not increase the volume of water transpired by the plant?

16 / 25

What is translocation the movement of?

17 / 25

In terms of translocation, what is an 'assimilate'?

18 / 25

Which of the following is an example of a 'source' ?

19 / 25

Which of the following is an example of a 'sink' ?

20 / 25

The Mass Flow Hypothesis, is the best explanation for translocation in plants. What does it suggest happens at 'sources'?

21 / 25

In the mass flow hypothesis, the water potential is reduced in the phloem near the sources. What will happen to water movement?

22 / 25

What happens to the solutes at the sink?

23 / 25

At the sink, solutes are removed from the phloem, what effect does this have on water movement?

24 / 25

Which of the following is evidence against the mass flow hypothesis?

25 / 25

If a small tube is inserted into the phloem through the bark of a tree, sap containing sucrose leaks out. Where on the tree will the most sap leak from due to the highest hydrostatic pressure?

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