when the genotype consists of a dominant and a recessive allele the phenotype will be like the allele

HESI A2

HESI A2 Biology Practice Test

1. When the genotype consists of a dominant and a recessive allele, the phenotype will be like the _ allele.

A. Dominant
B. Recessive
C. Both
D. Neither

Correct answer: A

Rationale: When the genotype consists of a dominant and a recessive allele, the phenotype will be like the dominant allele. This is because dominant alleles typically mask the expression of recessive alleles. Therefore, the dominant allele will be expressed in the phenotype in most basic cases. The recessive allele will only be expressed phenotypically if the individual is homozygous recessive. Choice B, 'Recessive,' is incorrect because the phenotype will not be like the recessive allele in this case. Choice C, 'Both,' is incorrect because in simple dominant-recessive inheritance, the dominant allele will overshadow the recessive allele. Choice D, 'Neither,' is incorrect as the phenotype will resemble the dominant allele.

2. What happens to messenger RNA when it reaches the cytoplasm?

A. It attaches to a ribosome.
B. It unzips, exposing nitrogen bases.
C. It pairs with the DNA bases.
D. It pulls free of the DNA strand.

Correct answer: A

Rationale: Messenger RNA (mRNA) carries genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm. When mRNA reaches the cytoplasm, it attaches to a ribosome. The ribosome functions as the site for protein synthesis through translation, where the genetic code carried by mRNA is read and translated into a specific sequence of amino acids. Choices B, C, and D are incorrect because mRNA does not unzip, expose nitrogen bases, pair with DNA bases, or pull free of the DNA strand in the cytoplasm. The primary function of mRNA in the cytoplasm is to serve as a template for protein synthesis by binding to ribosomes.

3. Which of the following describes how a bacterium reproduces?

A. Mitosis
B. Meiosis
C. Binary fission
D. Cytokinesis

Correct answer: C

Rationale: Bacteria reproduce through a process called 'binary fission.' During binary fission, a bacterium duplicates its DNA and then divides into two identical daughter cells. This method is the primary way bacteria replicate. Choice A, 'Mitosis,' is incorrect because mitosis is a process specific to eukaryotic cells, where the nucleus divides to produce two identical nuclei. Choice B, 'Meiosis,' is incorrect as meiosis is a specialized type of cell division that produces gametes with half the chromosome number. Choice D, 'Cytokinesis,' is not the correct answer as cytokinesis is the physical process of cell division, which occurs after the genetic material has been divided in mitosis or meiosis.

4. The force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere is the ______.

A. Atmospheric pressure
B. Barometric density
C. Aneroid pressure
D. Barometric pressure

Correct answer: A

Rationale: Atmospheric pressure is the correct term for the force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere. It is commonly measured in units such as pascals, millibars, or inches of mercury. Barometric density and aneroid pressure are not accurate descriptions for this phenomenon. Barometric density refers to the density of the atmosphere at a particular location, while aneroid pressure is linked to a type of barometer but not a comprehensive term for the force exerted by the weight of air.

5. Why is the nucleus important in a cell?

A. It stores the DNA
B. It supports the cell
C. It makes protein
D. It makes energy out of food

Correct answer: A

Rationale: The nucleus is important in a cell because it stores the DNA, which contains the genetic information necessary for the cell's function and replication. This genetic material controls the cell's activities and characteristics. Choices B, C, and D are incorrect because supporting the cell, making proteins, and producing energy are functions typically associated with other cell organelles like the cytoskeleton, ribosomes, and mitochondria, respectively.