50 percent of the offspring would be expected to have the ability to roll their tongues If a heterozygous male is crossed with a homozygous recessive female.
Explanation:
Information given:
the ability to roll tongue is dominant, the genotype would be RR, Rr
the inability to roll tongue is recessive trait the genotype = rr
Given that heterozygous male is crossed with homozygous recessive female, the genotype is
Rr X rr
Punnet square shows that:
R r
r Rr rr
r Rr rr The genotype ratio is 1:1
phenotype ratio is 1:1
There are chances of 50 % offspring having the ability to roll their tongues as they are heterozygous and have the dominant allele for rolling of tongues.
The Ras protein found in tumors usually cause which of the following events to occur excessive cell division.
<h3>How does Ras oncogene contribute to cancer?</h3>
Ras genes codes for proteins that can drive cancer when mutated.
All Ras proteins are GTPases which work as molecular regulators in the cell, controlling signaling pathways and other interactions.
Thus, option "A" is correct.
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The four laws or principles that are involved with the study of Stratigraphy are the following:
1. Principle of original horizontality
2. Law of superposition
3. Law of crosscutting relationships
4. Principle of Lateral Continuity
5. Principle of Faunal Succession
6. The Law of inclusions
Therefore, the correct answers would be 1, 2 and 4. Hope this answer helps.
The EMB (Eosin Methylene Blue) agar is a selective and differential agar medium. It contains sucrose and lactose as fermentable substrates together with Eosin Y and methylene blue dyes which in combination gives the agar its characteristic color when prepared and serves as a pH indicator as well as an inhibitor of growth of Gram-positive bacteria. Hence, it is primarily used to isolate Gram-negative fecal coliforms while some positive fecal coliforms such as Staphylococci are also able to grow.
These coliforms are of two types:
- Lactose or sucrose fermenting coliforms form metallic sheens on the agar as a result of acid production and the response of the indicator to the increased acidity.
- Non-lactose/sucrose fermenters are only able to produce acid by protein deamination. Hence they either form colorless or pinkish colonies on the agar
On the other hand, Mannitol salt agar is a selective and differential agar medium that is primarily used to isolate Staphylococcal bacteria. The presence of sodium chloride in the medium makes it a partial or complete inhibitor of other bacteria.
Hence, an unknown bacterium that forms colorless colonies on EMB will either be a non-lactose fermenting, Gram-negative coliform that will hardly grow on Mannitol salt agar, or a Gram-positive fecal Staphylococcus.
Staphylococci bacteria are of two types:
- Coagulase-positive will form yellow colonies on the Mannitol salt agar.
- Coagulase-negative will form red colonies on the Mannitol salt agar.
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