Arteries, Veins, Capillaries

Feature	Arteries	Veins	Capillaries
Physiology	Thick, muscular walls Diameter of lumen is smaller than vein Smooth muscle layer and connective tissue layer is thicker than vein. (not important to compare the ephithelial tissue between arteries and veins.	Muscular walls but thinner than arteries Diameter of lumen is larger than arteries. However smooth muscle layer and connective tissue layer is thinner than arteries.	Walls are made of epithelial/endothelial tissue that is 1-cell thick, absence of smooth muscle. This enables rapid diffusion of oxygen and carbon dioxide between red blood cells and the surrounding tissue. Lumen of capillaries are so small that red blood cells travel in a single file, slow enough for gaseous exchange to occur.
Functionality	Carry blood away from heart Carry oxygenated blood (except pulmonary artery)	Carry blood to the heart Carry de-oxygenated blood (except pulmonary vein)	Allow exchange of gases between red blood cells in the blood and the surrounding tissue and cells.
Presence of valves	Absence of valves (except pulmonary artery and aorta)	Presence of valves	Absence of valves.
		Skeletal muscle contractions squeeze blood in veins to allow it to flow through the veins at low pressure and velocity.
Pressure	High	Low	Lowest
Elasticity	More elastic	Less elastic

Components of blood
Plasma	Red blood cells	White blood cells	Platelets
Almost transparent liquid.	Circular biconcave shape (no nucleus) More flexible to squeeze through walls of capillaries and no nucleus = more haemoglobin to bind with oxygen = more efficient transport.	Irregular shaped nucleus (bilobed, trilobed etc.) Largest cells in blood	Smallest cells in blood.
90% water +blood electrolytes etc. help maintain osmotic balance and buffer at pH 7.4	Contains haemoglobin which binds reversibly to oxygen	Defends the body against invading pathogens. (produces antibodies,
A medium of transport.	Each haemoglobin binds with 4 molecules of oxygen so 1 red blood cell can transport up to a billion molecules	When present in large quantities, white blood cells will start destroying the body’s own cells etc. (leukemia)
	Short live span Destroyed in the liver/spleen after 100? days because the body cannot break down iron properly.

Evolution

Evolution

Black – FALSE

Red - TRUE

1.     The evolution of major groups of animals and plants is not an observed fact.

2.     Evolution is not something you should either believe in, or not believe in.

3.     Evolution is a not a process which involved the origin of life.

4.     Evolution is not primarily concerned with the origin of humans.

5.     According to evolution, people did not come from monkeys a long time ago.

6.     Evolution was not first proposed and explained by Charles Darwin.

7.     Evolution is not also known as ‘natural selection’.

-Natural selection is the pressure exerted by the environment/community for the species to adapt.

8.     Evolution is something which happened only in the past, it is not happening now.

9.     Evolution is something which happens to individual organisms.

10. Evolution is a totally random process, a series of ‘accidents.

11. Evolution is only a theory.

-It is not! (molecular evidence)

12. There is actually very little evidence for evolution.

13. Fossils reveal many problems which evolution cannot explain.

14. Biological, medical and agricultural research is increasingly based on the assumption that evolution occurs.

15. Evolution has been tested and challenged many times, but has always been supported by the results.

16. Dinosaurs lived during the time of early humans.

17. Evolution involves individuals changing in order to adapt to the environment.

-Evolution is over many generations, not suddenly develop the desired characteristics. ADAPTATION =/= EVOLUTION!

18. There is considerable observed evidence against evolution.

19. Science can productively study the past, based on evidence, so evolution is a proper subject for science.

20. The formation of complex structures, like the eye, can be readily explained by evolution.

21.  21. A volcano erupted on an island. The ash released from the volcano changed the acidity (pH) of the soil from the level it had been for hundreds of years. This significant change resulted in new environmental pressures on species in the soil. Which of the following is a likely outcome of these pressures?

-Some species will disappear from the soil because they do not have individuals with traits that allow them to survive in more acidic soil.

-Only some species will generate the needed mutations to adapt to the change in pH; other species will become extinct.

-Most species gain additional genetically-based traits, and this increase in complexity allows them to live in the more acidic soil.

-Individuals in each species will evolve the traits necessary to survive under these new conditions.

22. Bacillus thuringienses (Bt) bacteria produce a natural insecticide. Widespread use of Bt has lead to Bt resistance among insects. Why is this occurring?

-Individual insects that have mutations providing resistance to Bt can survive in the presence of Bt. The survivors pass this Bt resistance on to their offspring.

-Bt-resistant insects increase in the population by chance. There are so many insects that some of them are resistant to each type of insecticide.

-In the presence of Bt, individual insects evolve to become Bt resistant.

-Natural selection causes insects to generate genes providing resistance to Bt.

23. A given plant population is pollinated exclusively by a particular bee. A wet spring leads to a disease that wipes out all of the bees in the plant’s habitat. What is the likely outcome for this plant population?

-A mutation will arise which will allow the plants to be pollinated by other insects.

-Because they need to change their pollinators, some plant individuals will adapt to be pollinated by other insects.

-This plant population will die off.

-Enough variation exists within the plant population to allow it to adapt to any environmental challenge.

24.

-A seal is more closely related to a horse than to a whale.

-A seal is more closely related to a whale than to a horse.

-A seal is equally related to a horse and a whale.

-A seal is related to a whale, but is not related to a horse.

Circulatory System

Why do people have redder faces after exercise?

During exercise, the heart would pump harder and more frequently to meet the body’s increase in oxygen and nutrient demands. This harder and more frequently pumping would increase the rate at which oxygen and nutrients are transported to other parts of the body as a faster rate. The increase in rate of respiration increases the amount of heat produced. The blood vessels at the skin surface would dilate to allow more heat to be loss into the environment. This dilatation of the blood vessels at the skin surface provides more space for the blood to flow. This would lead to an increase the amount of blood flowing through, thus giving someone a flushed look.  

The heart pumps harder so as to meet the body's increase demand for oxygen and nutrients to produce more energy through respiration. The harder the heart pumps, the harder the ventricular contractions to increase the rate of oxygen and nutrients being transported around the body. The blood vessels at the skin surface will dilate due to the increased frequency of blood flow. This increases frequency produces heat which is lost to the environment, causing flushed cheeks.

How does smoking affect the circulatory system?

The smoke from the cigarettes causes the platelets to become sticky and therefore more likely form blood clots. These blood clots will prevent blood from flowing through, thus diminishing the blood flow to the heart and various body parts. This results in a decreased amount of nutrients and oxygen reaching the different parts of the body, leading to potential heart attack. Also, the carbon monoxide in the smoke will bind irreversibly with the red blood cells, decreasing its oxygen carrying-capacity. This results in a decreased supply of oxygen being transported around the body and to the heart, thus also leading to potential heart failure.