Cell membranes are based on the framework of fit base molecules called phospholipids which physically prevent water loving So D
Complete question:
A female is born with attached earlobes, which is a recessive phenotype. Which of the following statements about her parents must be true?
a. neither has the codominant allele.
b. Her father has an inactivated allele.
c. Both parents have the recessive allele.
d. Her mother carries the dominant allele.
Answer:
c. Both parents have the recessive allele.
Explanation:
A recessive trait is expressed in homozygous recessive genotypes only. If a female expresses the attached earlobe phenotype, she should be homozygous for the allele since the attached earlobe is a recessive trait. If allele "a" gives attached earlobe phenotype in homozygous genotype, the genotype of the female would be "aa". This means that the female has got one copy of the allele "a" from her either parents. Therefore, both her parents should have at least one copy of the recessive allele "a".
Question:
A---enzyme A------>B----enzyme B------>C
Refer to the metabolic pathway illustrated above. If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme A would be able to grow on medium supplemented with _____.
A) nutrient A only
B) nutrient B only
C) nutrient C only
D) nutrients A and C
Answer:
B) nutrient B only
Explanation:
The mutant has a mutation in the gene that codes for the enzyme A. Therefore, this mutant would not be able to convert the substance A into B. Without the presence of substance B, the final product can not be formed. However, if the mutant is supplemented with the substrate "B", it can convert the B into the final product (substance C). Therefore, the mutant would be able to grow in the medium to which the already prepared substance B has been added.
A single mutation can have a large effect, but in many cases, evolutionary change is based on the accumulation of many mutations. Gene flow is any movement of genes from onepopulation to another and is an important source of genetic variation.
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C. Experimental
Explanation - The cause and effect of a process would be studied in experimental investigations. However, in descriptive studies, relationship between the factors are not studies rather the detail of the process is studied. In comparative investigation, several factors are compared and its effects are analyzed.
In experimental investigations, experiments are carried out based on the hypothesis and then it is validated accordingly. Validation is a must to prove and disprove the hypothesis. Therefore, experimental data and hypothesis are related.
