Answer:
a. Heterozygous individuals may pass on their copy of the disease-causing allele to offspring.
Explanation:
Tay-Sachs, which is a recessive lethal disease ---- Let say the recessive lethal diseases is s
∴ it only results when an individual posses two copies of the diseases-causing allele i.e two copies of the disease will be ss.
Now, when two hetrozygous individuals crossed , it is obvious that each can pass on their copy of the disease-causing allele to the offspring.
Let show an illustration for the above statement.
Let the heterozygous individual be Ts, if Ts cross with another Ts;
we will have:
Ts × Ts
T s
T TT Ts
s Ts ss
the offspring are TT,Ts,Ts,ss
We can now see how the Heterozygous individuals pass on their copy of the disease-causing allele to the offspring (Ts).
Answer:
True
Explanation:
Some deviations from normal homeostasis activate the positive feedback loops to control the conditions which are otherwise regulated by negative feedback mechanisms.
For example, the blood levels of respiratory gases and H+ ions are regulated by a negative feedback system via chemoreceptors. The increased partial pressure of carbon dioxide gas and lowered pH or lowered partial pressure of oxygen in the blood are sense by central and peripheral chemoreceptors which in turn activate the neurons of the dorsal respiratory group (DRG).
The activated DRG triggers an increased in the rate and depth of the breathing to facilitate the inhalation of more oxygen and exhalation of CO2 to restore the normal levels.
However, hypocapnia inactivates the chemoreceptors and does not allow negative feedback to restore the normal CO2 levels in the blood.
Under such conditions, the positive feedback loop stimulates the DRG neurons more strongly in response to the increased partial pressure of CO2 above the normal levels than when the partial pressure of oxygen falls below the normal level. These dangerously lowered oxygen levels may also cause fainting.
Insulin causes blood glucose levels to drop, which signals the pancreas to stop producing insulin in a negative feedback loop. Hormonal stimuli refer to the release of a hormone in response to another hormone. A number of endocrine glands release hormones when stimulated by hormones released by other endocrine organs.
1. They are easy to raise.
2. Have many offspring during per mating.
3. It can fertilize itself.
4. It has varieties in genotype that is easy observable.
5. It has phenotype that is also easy observable.