Answer:
E. They decrease the rate at which Ras hydrolyzes GTP.
Explanation:
Activated Ras has GTP bound to it, this propagates an intracellular signal to the nucleus where cell proliferation is induced. Thereafter proliferation is switched off by the hydrolysis of the bound GTP to GDP.
Therefore decreasing the rate of GTP hydrolysis causes Ras to remain active, ultimately leading to uncontrollable proliferation characteristic of cancer.
<span>1. is exothermic
2. is current electricity
3. is static electricity
4. is outer ear
5. is compression</span>
Answer:
Crossing two chickens heterozygous for the trait feather color, when brown feathers are dominant over red feathers, will produce offspring with brown and red feathers in a brown:red phenotypic ratio of 3:1.
Explanation:
Knowing that in chickens brown feathers are the expression of the dominant allele (B) and the recessive allele is red (b), crossing two heterozygous individuals (Bb) will result in offspring that are likely to have brown or red feathers.
The cross can be represented by a Punnett Square:
<u>Bb X Bb cross
</u>
alleles B b
B BB Bb
b Bb bb
Where the result is:
<u>Genotypes</u>:
<u>Phenotypes</u>:
- Brown feathers, 75%
- Red feathers, 25%.
In this case, the probability of having brown or red feathers is 3:1.
Answer:
B (active transport using ATP)
Explanation:
Movement of substances normally occur in the direction of concentration gradient/difference i.e. the difference in concentration of a substance across a membrane. Letting molecules diffuse or pass down their concentration gradient does not require energy but pumping those molecules against gradient requires energy in form of Adenosine triphosphate (ATP). This process is called Active transport.
In order to perform certain cellular processes, cells need to move substances from their surroundings into the cell across their cell membrane. Moving this substances against the concentration gradient between the cell membrane and its extracellular fluid requires energy (ATP).
An example is the sodium-pottasium pump employed by animal cells in which they expend energy to move K+ molecules into the cell and Na+ molecules outside the cell against the concentration gradient of their cell membrane and extracellular solution.
