Nursing Elites

1. Choose the two bases that have two carbon rings:

• A. Adenine
• B. Cytosine
• C. Thymine
• D. Guanine

Correct answer: A

Rationale: Adenine and guanine have two carbon rings and are known as purines. These bases are found in nucleic acids such as DNA and RNA. Adenine (option A) and guanine (option D) are the correct choices as they both have two carbon rings in their molecular structure. Cytosine (option B) and thymine (option C) have a single carbon ring each, making them incorrect choices for bases with two carbon rings.

2. Which of the following is true of heterozygous traits?

• A. They are haploid
• B. They are denoted AA
• C. They are denoted aa
• D. They are denoted Aa

Correct answer: D

Rationale: Heterozygous traits are denoted by having two different alleles for a particular gene, represented as Aa. This means that they are not haploid (A), not denoted AA (B), and not denoted aa (C). Therefore, the correct answer is D, as heterozygous traits are represented as Aa.

3. Which structure controls the passage of substances into and out of the cell?

• A. Vacuole
• B. Cell Membrane
• C. Nuclear Membrane
• D. Cytoplasm

Correct answer: B

Rationale: The correct answer is the Cell Membrane. The cell membrane acts as a barrier that controls the passage of substances into and out of the cell. It is selectively permeable, allowing only certain molecules to pass through. Vacuole (Choice A), Nuclear Membrane (Choice C), and Cytoplasm (Choice D) do not primarily regulate the passage of substances in and out of the cell. Vacuoles are responsible for storage, the nuclear membrane surrounds the nucleus providing protection, and the cytoplasm is the fluid where organelles are suspended.

4. Which of the following molecules is an important component of the plasma membrane?

• A. Phospholipids
• B. Steroids
• C. Sugars
• D. Amino acids

Correct answer: A

Rationale: Phospholipids are indeed a crucial component of the plasma membrane. They have a unique structure with hydrophilic heads and hydrophobic tails, which allows them to form the lipid bilayer of the membrane. Steroids, sugars, and amino acids are not primary components of the plasma membrane. Steroids are a different type of lipid, sugars are often found in glycoproteins on the membrane surface, and amino acids are the building blocks of proteins, some of which are membrane proteins, but not the membrane itself.

5. How are molecules of water bonded to each other?

• A. Ionic
• B. Covalent
• C. Hydrogen
• D. Molecular

Correct answer: C

Rationale: Water molecules are bonded to each other by 'hydrogen' bonds. These bonds are not as strong as covalent bonds, which hold the atoms within each water molecule together (Choice B). Ionic bonds (Choice A) involve the transfer of electrons between atoms, which is not the case in water molecules. The term 'molecular' (Choice D) is too general and doesn't specifically describe the type of bond between water molecules.

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