Questions 2 - Levels of organization

Past paper questions

Some questions may have been modified to fit this blog format. 

1.a) Match the correct level of organization with an example of it. One has been done for you.

Answer:

Organelle → mitochondria

Tissue → phloem

Organ → heart

System → circulation

b) What level of organization does a chloroplast belong to?

Answer: it is an organelle. This is because it is found in the cytoplasm of a cell :)

2. a) Figure 1.2 shows structures that produce urine and excrete it from the body of a mammal. Label and name one organ.

Answer: the little bean shaped things at the sides are the kidneys.

b) Explain the difference between the terms organ and organ system.

Answer: An organ is made up of tissues with the same function. This organ carries out a particular function. An organ system is made up of many different organs with a common function and a type of link or communication between them.

Questions 1 - Living Organisms

Past Paper Questions

Note that some may have been reworded to fit this blog format

1.a) A student was asked to write a list of the characteristics shared by all living organisms. The list is shown below, but it is not complete. Complete the list by writing down the missing characteristics. (2 marks)

• Growth
• Excretion
• Movement
• Respiration
• Sensitivity
• ____________
• _____________

Answer: A simple way to do this would be to spell out Mrs Gren(c):

M - Movement, done!

R - Respiration, done!

S - Sensitivity, done!

G - Growth, done!

R - Reproduction, not done

E - Excretion, done!

N - Nutrition, not done

C - Control of internal conditions, not done but probably isn't included in this list anyway.

So you would complete the list by adding reproduction and nutrition! :)

b) Suggest why excretion is important to living organisms. (2 marks)

Answer : Waste produced from biological reactions can be toxic, and excretion is the removal of these products. This is necessary so the organism is not poisoned by its own toxic waste!

2. a) Living organisms can be put into major groups based on common features that they share. The table below shows some of the main groups of organisms, their features and examples of each. Complete the table to show the correct groups, two features of each group and an example of an organism in each group. (5 marks)

Answer: For an example of animals, you could literally write any animal you know. I'm going to say "mammoth" because I feel like it now, but I feel like it's better to talk about an animal that ISN'T extinct, so in an exam, I'd write something like "elephant". Features of bacteria include the fact that they are unicellular (are only made up of 1 cell) and do not contain a nucleus, only a chromosome of DNA. An example of a bacterium is pneumoccus, which is responsible for causing pneumonia. The third group is a virus. This can be seen from the fact that it is always parasitic and only reproduces inside living cells.

b) Organisms that cause disease are known as pathogens. Give two groups of organisms that include pathogens. (2 marks)

Answer: The safest things you can write are bacteria and viruses. Viruses are nearly always pathogenic and some bacteria are. I guess you could also write "protoctists" but that might be a little risky, though some are in fact pathogenic (like plasmodium).

2.37 Describe experiments to investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms

Experiment would be set up as follows to investigate release of carbon dioxide:

• Put x grams of germinating seeds in a test tube.
• Cover it with a bung/cork with a tube through it
• Have one end of the tube in limewater
• If it turns cloudy, carbon dioxide has been given off
• See figure 1

Figure 1: Apparatus

To investigate the release of heat:

• Put seeds in a test tube
• Seal it with a cotton puff
• Place a thermometer in it
• Place the setup in a cold room (no less than 15ºC)
• Measure initial temperature
• Measure temperature after x amount of time (eg 20 mins)
• Have another test tube, in the same room, with the same amount but have the seeds boiled. Leave it for the same amount of time.
• Compare test tube 1 and 2. :)

Figure 2: Apparatus

Note that all images used in this post were created by me.

2.48 Describe experiments to investigate the effect of exercise on breathing in humans.

When you exercise, sometimes you end up respiring anaerobically as the body cannot get oxygen around quickly enough. Of course, this depends on the intensity of the exercise. This could be investigated as follows:

• Ask a friend to volunteer 
• At rest, have them lie down on the ground (belly up) and count how many times their chest rises in one minute. Record the result.
• Now, ask them to walk 100m (or any other given distance). Measure their breathing rate the same way as before. 
• Then ask them to run 100m. Measure breathing rate again.
• Finally, ask them to sprint 100m. Measure their breathing rate again.
• Wait until the person's breathing rate has returned to normal. Repeat the experiment from the start 3 times.
• Take an average of the results
• Plot a graph of your results
• Remember to keep the person, distance run, and environment the same.

Dependent variable: Breathing rate (breaths per minute)

Independent variable: Intensity of exercise

Control variables: Distance (100m), person doing the exercise (fitness must be the same), environment (i.e not have one in super hot conditions and another in freezing cold)

Note: results that differ by more that 0.2 should be ignored and should thus not be taken into consideration when taking an average.

An example graph can be seen below. THIS GRAPH DOES NOT EXPRESS THE RESULTS OF THE EXACT EXPERIMENT DESCRIBED but it does express the same idea.

Conclusion: As exercise intensity increases, the breathing rate increases as well.

Sometimes, the image doesn't show up, so the link to it can be found here

2.46 Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries

The alveoli are adapted to the job of making gas exchange quick and effective because (they have...) :

• Walls one cell thick make diffusion quick and easy
• There are a lot and they look a bit like bunches of grapes, meaning an enormous surface area - this means the blood stream is in contact with a large surface, and gas exchange happens quickly
• Moist lining helps gases dissolve and diffuse into it
• Constant blood flow allows all the blood to be oxygenated effectively

Figure 1: Diagram :)

2.45 Understand the role of the intercostal muscles and the diaphragm in ventilation

Intercostal Muscles
As you breathe in...

• The muscles contract
• The ribs move up and outward

As you breathe out...

• The muscles relax
• Ribs move in and down

Diaphragm

As you breathe in...

• The diaphragm contracts, moving down
• Low pressure is created inside the lungs,  forcing air in
• Diaphragm pulls down

As you breathe out...

• The diaphragm relaxes 
• Pushes upwards
• High pressure is created inside the lungs, forcing air out

Source: BBC BitesizeFigure 1: A diagram of the respiratory system

2.44 Describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes

How air travels...
Mouth/nose→Trachea→Bronchi→Bronchioles→Alveoli→Gas exchange occurs and then the process happens in reverse (i.e. from alveoli to bronchioles)

The functions of each of these parts:

Ribs - These are curved bones that embrace and protect the lungs from damage. They are linked together by intercostal muscles.

Intercostal muscles - Located between the ribs and expand and contract as the lungs fill or deflate. They keep the ribs in place too.

Trachea - Lined with C shaped (or U shaped, depends how you think of it) rings of cartilage, these protect it from being crushed. This is the pipe that air travels down from the mouth or nose.

Bronchi - The two tube like structures that divide the trachea, one leading into each lung. 

Bronchioles - Smaller tube like structures that contain alveoli at the tips and lead the air in and out of them

Alveoli - Tiny, grape-like air sacs surrounded by capillaries where gaseous exchange occurs

Pleural membranes - The outer lining of the lungs, which would feel kind of wet, and stops the lungs sticking to the ribs, as well as reducing friction. 

Figure 1: A diagram of the human thorax