2.59 Explain how adaptations of red blood cells, including shape, structure and the presence of haemoglobin, make them suitable for the transport of oxygen

ADAPTATIONS TO SHAPE
Have a biconcave shape (flat disk with a dip in the middle) which increases the surface area (this allows more oxygen to be absorbed more efficiently). Also, the fact that they are a flat disk allows them to pass through capillaries easily :)

NO NUCLEUS
This means the whole cell is full of haemoglobin

THIN OUTER MEMBRANE
Which lets oxygen diffuse through easily

HAEMOGLOBIN
(It's made from iron), and can bond with oxygen (very important for cell whose job is to carry around oxygen)

NO MITOCHONDRIA
Because the cells respire anaerobically so the cells don't use any oxygen.

2.64 Explain how the heart rate changes during excercise, and under the influence of adrenalin

EXERCISE

Basically, when we exercise our muscles need more energy to work. Energy is created during respiration, and we need oxygen for respiration. Carbon dioxide is produced during respiration, so if there is more respiration occurring, there will be more carbon dioxide produced, so the heart needs to increase its speed so that more blood, which is carrying oxygen which will be sent to the muscles (it will also carry away the deoxygenated blood). Carbon dioxide is no good for respiration!

WHAT IS ADRENALIN?
According to Hannah*, it is...
produced in the adrenal glands in top of the kidneys- stimulates adrenegic receptors in the heart which increase the rate that your heart cells work at.

MORE ABOUT ADRENALIN 
(this part is written by me)
Adrenaline is a hormone, so it is carried around in the plasma part of your blood (see post on plasma) which is yellow. As mentioned above, it is produced in the adrenal gland.

Figure 1 - Just because I wanted a picture

*There's a hyperlink on the word "hannah" to her blog, because it was written by her - full credit to her, no plagiarism intended :)

2.63 Structure of the heart and how it works

Structure of the heart:

HOW IT WORKS:

Blood enters the right atrium (from the vena cava) and the tricuspid valve is closed. 
The walls of the atrium squeeze, raising the blood pressure and forcing open the tricuspid valve, allowing the blood to flow into the right ventricle. 
The ventricle contracts, raising blood pressure which closes the tricuspid valve and forces open the semilunar valve, forcing the blood through the pulmonary artery where it is oxygenated at the lungs 
The pulmonary vein fills the left atrium with blood. 
A similar process forces the blood into the left ventricle (the valve is the bicuspid)
When the left ventricle contracts the blood is forced out through the aorta, which is then pumped around the body.

Things to remember:
Veins lead to the heart; arteries lead away.
Atrium means entrance hall in Latin; hence the atrium is where blood enters the heart.
The left side is bigger than the right as it has to pump blood through the whole body (therefor the aorta is found on the left side and the vena cava enters on the right).
You talk about the heart from right to left, as if you were examining someone's heart and using their own left and right.

2.58 Understand the role of plasma in the transport of carbon dioxide, digested food, urea, hormones and heat energy

Plasma is made up of mostly water and is pale yellow in color (though I'm pretty sure you don't need to know that). This is a solvent, so things dissolve into the plasma, which is how they are carried around This transports carbon dioxide,  digested food, urea (basically urine...lovely), hormones and heat. 

Digested foods = soluble sugars and amino acids :)

Heat is important to regulate body temperature.

Figure 1 (below) shows a sample of plasma and blood - the plasma is the (rather gross-looking) yellow stuff above the red.

Figure 1

2.57 Describe the composition of the blood: red blood cells, white blood cells, platelets and plasma

• 55% of the blood is plasma
• More red blood cells than white blood cells
• Platelets

Platelets are fragments of dead cells.

White blood cells can be lymphocytes or phagocytes.

I don't know if this is technically needed in this specification point, but I'll include it anyway because...well...it's good to know. :)

\/

Phagocytes are the white blood cells that swallow up the pathogen (which can be a bacterium, virus or protoctist). As can be seen below in figure 1, the cytoplasm forms little 'feelers' called pseudopodia. These surround the pathogen and form a vacuole. Then, digestive enzymes are released into the vacuole which digest and kill the pathogen.

Lymphocytes release antibodies which are complimentary to the antigens on the surface of a pathogen - that is how they (pathogens) are identified. Lymphocytes can cause the pathogens to stick together, leave a clearer chemical trail (so the phagocytes can follow them more easily) or explode.

Erythrocytes, aka red blood cells, have a bioconcave shape, no nucleus and have lots of haemoglobin. This allows them to carry oxygen around the body.

Plasma is used to transport stuff (see next posts(s))

Figure 1

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).