Topic 6: Human Physiology
Salivary amylase digests:
Starches
What are the two types of tissue in vascular plants?
Xylem and Phloem.
What are the two forms of nuclear division?
Mitosis and Meiosis
After ingestion by humans, the first category of macromolecules to be chemically digested by enzymes in the mouth is:
Carbohydrates
How can plants limit the water vapour lost in transpiration?
Closing of Stomata
The F2 phenotypic ratio is ?:?:?:? for a dihybrid cross between two heterozygous parents if the two genes involved are unlinked and show independent assortment.
9:3:3:1
Following the completion of digestion of starch in the small intestine, the dissolved products are absorbed and transported to the:
Liver
Describe the properties of water involved in transpiration:
Cohesion: water molecules form weak hydrogen bonds with each other due to their polarity. This allows transpiration pull to extend, unbroken, through long columns of water in xylem vessels.
Adhesion:the polarity of water also interacts with the hydrophilic cellulose in the cell walls of the leaf. This helps create the pull that draws water out of the xylem and into the leaf cells.
Explain the 3 types of stabilization (regarding natural selection)?
Stabilizing selection is widespread. It occurs when the existing variations that are beneficial are already common. Stabilising selection acts against extremes of a trait.
Directional selection occurs when one extreme of a trait offers a survival or reproductive advantage. Directional selection increases allele frequencies at one phenotypic extreme and reduces them at the other.
In disruptive selection, the most frequent phenotype becomes a disadvantage, and individuals at both extremes have better rates of survival and reproduction.
Distinguish between the structure and function of an artery and a vein.
An artery carries blood at high pressure from the heart to the body or lungs, a vein carries blood at low pressure from the body or lungs to the heart. Due to the pressure difference, artery walls are thick with large amounts of muscular tissue and collagen; vein walls are thinner with less collagen and little muscle but do have valves to prevent backflow of blood. Arteries have a small lumen with rapidly flowing blood whereas veins have a large lumen with slow-flowing blood.
Name 3 internal and external (environmental) factors that could effect the rate of transpiration:
Some internal factors include:
Some external (environmental) factors include:
What is reproductive isolation?
the failure of individuals from two populations to mate and produce fertile offspring, resulting in the reduction or elimination of gene flow between the populations.
What hormones are involved in blood glucose homeostasis and how do they effect blood sugar concentration?
If higher than normal: Insulin – produced and secreted by β-cells. Levels will fall: insulin stimulates glucose uptake into muscles and liver cells, where it is converted into glycogen.
If lower than normal: Glucagon – produced and secreted by α-cells. Levels will rise: Glucagon stimulates glycogen hydrolysis to glucose in the liver, which in turn releases glucose into the blood.
In the shoot, auxin controls:
How does a home pregnancy test work?
The test works as follows:
(a) The test stick is dipped into the woman’s urine.
(b) The test stick contains anti-hCG antibodies with attached blue dye. If hCG is present it will bind to the antibodies.
(c) Monoclonal antibodies are attached to the membrane within a window on the test stick. If hCG is present in the urine and bound to the anti-hCG antibodies, the hCG will also bind to the monoclonal antibodies as it travels up the stick. This complex also contains the blue dye which shows a blue line within the window. This blue line indicates the presence of hCG and therefore a positive result.
(d) The urine continues to move up the test stick. As it reaches the top there is another line of monoclonal antibodies. These antibodies are a complementary shape to the anti-hCG. The anti-hCG is always present therefore this line will always turn blue as a result of the blue dye. This line acts as a control and allows the user to check if the test is working. This line does not indicate whether the user is pregnant or not.