Answer:
A. decrease by half.
B. stay the same.
C. double.
Explanation:
Host-pathogen models resembels the host-parasite models and predator-prey which is used to evaluate the evolutionary strategies of pathogens.
The host-vector-pathogen system can be demonstarted as a change in the number of 4 types of people: healthy hosts, uninfected vectors, infected hosts, and infected vectors.
The threshold density should decrease by half, stay the same, or double, according to the standard host-pathogen model, if the combined death and recovery rate from a disease doubles, and the ability of the disease to spread from infected to uninfected persons.
Hence, the correct options are A. decrease by half, B. stay the same, and C. double.
To first dive into your question, here are some vocabulary terms that I will be using and will be helpful to you as well.
- Homozygous dominant (BB): <em>Is not affected by cystic fibrosis</em>.
- Homozygous recessive (bb):<em> Is affected by cystic fibrosis</em>.
- Heterozygous (Bb):<em> A carrier for cystic fibrosis</em>.
- Phenotype (Ex: Having cystic fibrosis): <em>The appearance of an allele pair</em>.
- Genotype (Ex: bb): <em>The genetic makeup of an allele pair</em>.
We know that if both of the parents are phenotypically normal, there is no way that they can be homozygous recessive (bb), or have cystic fibrosis. We also know that since they have a child with this disease, they can't be homozygous dominant (BB) either. This means that <u>both parents have to be carriers (Bb)</u> in order for them to have a child with cystic fibrosis.
Below I have attached a Punnett square with both of the heterozygous parents.
<em>Each child they have will have a </em><u><em>1/4</em></u><em> or </em><u><em>25%</em></u><em> chance of having cystic fibrosis.</em>
Answer: True
Explanation:
A cataract is a clouding of the lens of your eye. As one ages, proteins in the lens begin to break down and the lens becomes cloudy. One may not even realize they have a cataract because it usually grows very slowly and may not impede vision early on. While cataracts are rarely dangerous, after a number of years they will likely affect vision. Its important to note also that cataract is not caused by overuse of the eyes and it does not travel from one eye to the other.
Risk factors include aging, family history, high blood pressure, previous eye injury, smoking, obesity, heavy drinking and diabetes.
Therefore, from the above risk factors, we could expound that blood type (exposure) has no relationship with cataract.
The answer is a Gland.
It is a cell or organ that secretes substances for use elsewhere in the body, or for elimination as waste. Secretion being a product of gland if it's useful to the body and an excretion being a product of the gland if it's a waste product. Glands may be exocrine or endocrine; endocrine glands lose contact with surface; have no ducts; secretes products directly into the blood due to having a high density of blood capillaries while exocrine glands secretes to the body surface or lumen; and maintain contact with surface via a duct.
