Monthly Archives: October 2012

6.5a: Homeostasis – Thermoregulation

Data-based question: wind-chill nomogram 

1. 7 MJ m^-2h^-1

2. The person would feel very cool.

3. wind chill of 0.9 MJ m^-2h^-1 X 2= 18. Therefore about 1.8 MJ m^-2h^-1 lost.

4. The increase in wind-speed causes an increase in wind-chill as well. However, the increase in temperature causes the decrease in wind chill.



6.4: Gas Exchange

1. The oxygen concentration in the alveoli is not as high as in fresh air that is inhaled because some of the oxygen has diffused to capillaries surrounding the alveoli.

2a. (105-40)/40   X 100= 163%

2b. The process caused by this concentration diference is diffusion.

2ci. (27-2.5)/2.5   X 100= 980%

2cii. This means that the carbon dioxide concentration has increased by 980% in the air exhaled from the air inhaled. This is caused by the diffusion of carbon dioxide from the blood into the alveoli, causing the carbon dioxide concentration to increase in the alveolus.

2d. The body doesn’t use nitrogen therefore it does not diffuse from the air to the blood, causing no difference to appear in the concentration.

6.2b: The Transport System

Blood Vessels

The walls of the blood vessels consist of a series of layers, the tunica intima, tunica media, and tunica adventitia. These layers vary in thickness and are not always present in blood vessels. A relationship does exist between the structure of the blood vessel wall and its function.

The Structure of Blood

The fluid between blood cells in the plasma. It is mostly water and also contains other substances such as glucose, oxygen, and carbon dioxide, waste products such as urea, hormones, mineral salts and plasma proteins such as antibodies. Mineral salts and plasma proteins are continuously present in the blood while other substances move from one part of the body to another. In addition to this, blood also takes heat from warmer to cooler parts of the body.

The remainder of the tissue contains blood cells and platelets. Most of the cells are red blood cells that contain hemoglobin while the remaining are while blood cells, or leucocytes whose job is to fight against diseases. Leucocytes are classified as phagocytes which engulf foreign material adn lymphocytes which produce antibodies.

Questions about Art

What is art?

Where is art found?

Can music be art?

Can writing be art?

When did art start?

Who started art?

Is art important?

Why is art important?

How do you do art?

Is art creative?

Is art real?

Is art personal?

What forms of art are there?

Can art ever end?

What does art include?

Who can do art?

Are you born with art?

Do you have to learn art?

What do you use for art?

Do you use visuals?

Does art include books?

Are there any rules for art?

Is there a specific way to do art?

Is color part of art?

What is used in visual arts?

What is the most used art form?

Is there a most used art form?

Does art vary for different cultures?

6.2a The transport system

Data-based question: heart action and blood pressures

1. Blood is pumped from the atrium to the ventricle from 0 to 0.1 seconds.

2. The ventricle starts to contract from 0.1 seconds

3. The atrioventricular valve is closes from 0.1, the same time as the arterial pressure falls below the ventricle pressure.

4. The semilunar valve opens at 0.15 seconds as the ventricle pressure rises above the arterial pressure.

5. The semilunar valve closes at 0.4 seconds as the ventricular pressure falls blow arterial pressure.

6. The blood is being pumped from the ventricle to the artery from 0.15 to 4 seconds.

7. Blood in the ventricle is at a maximum at 0.1 seconds. Blood in the ventricle is at a minimum at 0.35 seconds.

6.1 Digestion

Data-based question: the wall of the esophagus

2. The difference occurs because the esophagus transport food to the stomach but since the food transported to the mouth is insoluble, friction will occur in the walls of the oesophagus. Since there is no absorption in the oesophagus multiple layers are not a problem. However, in the intestine and stomach absorption is important therefore one layer is advantageous.

3. X contains the circular muscle fibers while Y are the longitudinal fiber.

4. The mucus would be useful for the small glands to secrete and move food to the stomach.

5. The esophagus wall needs a supply of blood to provide oxygen for respiration and support the growth of the tissue.


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D.4: Hardy-Weinberg Equilibrium

Hardy-Weinberg equilibrium

A population is either evolving or is in genetic equilibrium, also known as the Hardy-Weinberg equilibrium. For genetic equilibrium to exist, there can be no mutations, no migration, no natural selection, and random mating to have a sufficient sample size. If a population is in genetic equilibrium, predictions can be made about the frequencies of alleles, genotype and phenotype. The frequency of dominant alleles is usually represented by p while the frequency of recessive alleles are represented by q. The probability of an individual having the homozygous recessive is q X q and the probability of an individual having the homozygous dominant genotype is p X p. The probability of having the heterozygous genotype is 2 X p X q. This is because both the dominant allele and recessive allele can come from either parent.

D.5b: Phylogeny & systematics

Data-based question: inferring evolutionary relationships

1a. Cytochrome C is identical in all three animals.

1b. The ancestors of she eps diverged more recently compared to pigs. This is because sheep have fewer base substitutions therefore these species are more closely related.

1c. The percentage of base substitutions can be used as a molecular clock. If there are more mutations, it shows that more time has passed for the mutations to accumulate therefore, we can see that pigs diverged earlier than sheep.

2. Knowing the morphology or protein structure can help construct a better tree as we can then create a phylogeny tree that fits the data best.


D.5a: Phylogeny & systematics

Phylogeny and systematics

Taxonomy is the classification of organisms that allows for effective communication between scientists as there is more consensus of the names. Initially, taxonomy was done used morphology by examine the form and structure. However, convergent organisms can lead to morphological similarities which suggests that there is a closer evolutionary relationship which may not be the case. Similarities between species can be homologous or analogous. Homologous structures are similar due to ancestry while analogous structures are similar due to convergent evolution. Classifications are increasingly becoming based on theories or evidence of evolutionary relationships. The advantage of this is that it gives a greater power to predict. If several members of a group have a characteristic it suggest that it is likely to be present in a relative.

A cladogram is a tree-like structure that divides in a binary pattern. A clade is a group that includes an ancestral species and all the descendants of that species. Members of a clade share a set of features which were not present in more distant ancestors but are shade by members of a clade. If the shared characteristics are homologous, the cladogram can be the basis of a phylogenetic tree. A phylogenetic tree also includes a time scale which is not included in a cladogram.