Answer:
Methotrexate inhibits the synthesis of DNA, RNA, and protein synthesis of the cells in the experiment.
Explanation:
Methotrexate competitively inhibits the enzyme dihydrofolate reductase (DHFR) which is involved in the synthesis of tetrahydrofolate from the inactive dihydrofolate. The methotrexate blocks the enzyme by binding to its active site thereby preventing further reaction of the dihydrofolate reductase enzyme and dihydrofolate. Tetrahydrofolate is a useful material for the de novo synthesis of thymidine, a nucleoside. And without thymidine, DNA synthesis is hindered. Methotrexate therefore inhibits the synthesis of DNA, RNA, thymidylates and of course protein synthesis.
A decreased pH coupled with a decreased plasma concentration of bicarbonate ion indicates that acidosis is occurring and the respiratory system will compensate for this change.
<span>Acidosis (metabolic) is a state when increased acidity in the blood occurs and it usually refers when arterial pH falls below 7.35. Metabolic acidosis may result from increased production of metabolic acids (lactic, for example) and is characterized by low pH, low blood HCO3, and normal or low PaCO2. Metabolic acidosis is compensated with an increased exhalation of CO2 to reduce metabolic acid.</span>
Answer:
Limits to variation The most obvious limit to natural selection is that suitable variation may not be available. This may be because certain phenotypes cannot be built, being ruled out either by physical law or by the properties of biological materials.
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Answer:
Both A and B
Explanation:
True breed is a breed that is 100% identical with the parent, the traits inherited from that parents are 100% controlled by same allele of a gene hence they are exact copy.
A single gene can have several alleles, it is the allele that combines together that determines what is seen or expressed.
Allele for blue colour is dominant over allele for red color and that is what led to the phenotypic appearance of the offspring which is blue and the red color is masked. Also, because they are true breeds it means the genotype have the same allele e.g. AA
The producers convert <span>carbon into a form that is available to primary consumers.</span>
