what type of bond holds water molecules together

ATI TEAS 7

Practice TEAS Science Test

1. What type of bond holds water molecules together?

A. Covalent bond
B. Hydrogen bond
C. Ionic bond
D. Peptide bond

Correct answer: B

Rationale: The correct answer is B: Hydrogen bond. Hydrogen bonds are responsible for holding water molecules together. In a water molecule, the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive, creating a partial positive and negative charge. This polarity allows hydrogen bonds to form between adjacent water molecules. Covalent bonds involve the sharing of electrons, ionic bonds involve transfer of electrons between ions, and peptide bonds are specific to linking amino acids in proteins, which are not relevant to water molecule interactions.

2. Which of the following statements is NOT true about DNA?

A. DNA contains the nucleotides A, T, C, G and is read 5' to 3'.
B. DNA contains genetic information and is tightly coiled with proteins to form chromosomes.
C. DNA contains the nucleotides A, T, C, G and is read 3' to 5'.
D. DNA is a double-stranded molecule connected by hydrogen bonds.

Correct answer: C

Rationale: The correct answer is C because DNA is typically read from the 5' end to the 3' end, not from 3' to 5'. Choices A, B, and D are all true statements about DNA. DNA contains the nucleotides A, T, C, G and is read in a 5' to 3' direction. DNA also contains genetic information and is tightly coiled with proteins to form chromosomes. Additionally, DNA is a double-stranded molecule connected by hydrogen bonds.

3. Which of the following statements regarding the pericardium is not correct?

A. It allows for the heart to work in a relatively friction-free environment
B. It is a single-walled layer around the heart
C. It prevents overfilling of the heart with blood
D. It protects and anchors the heart

Correct answer: B

Rationale: The correct statement about the pericardium is that it is double-walled, not single-walled. Choice A is correct because the pericardium does allow the heart to work in a relatively friction-free environment, reducing friction during heartbeats. Choice C is correct as the pericardium helps prevent the overfilling of the heart with blood. Choice D is also correct as the pericardium serves to protect and anchor the heart in place within the chest cavity.

4. What is the body's primary defense against pathogens?

A. Phagocytes
B. Antibodies
C. Memory B cells
D. T lymphocytes

Correct answer: A

Rationale: The correct answer is A: Phagocytes. Phagocytes are the body's first line of defense against pathogens. They are innate immune cells that engulf and digest foreign particles like bacteria and viruses, preventing infections. Phagocytes act as the initial barrier to invading pathogens and are part of the innate immune response. Choice B, Antibodies, are produced by B cells in the adaptive immune response. Choice C, Memory B cells, are also part of the adaptive immune response and provide a faster and stronger response upon re-exposure to pathogens. Choice D, T lymphocytes, are part of the adaptive immune response, particularly involved in cell-mediated immunity.

5. When is work done by a force on an object?

A. Only when the object moves in the direction of the force
B. Only when the object moves against the force
C. Only when the object moves vertically
D. Only when the force is applied for a specific duration

Correct answer: A

Rationale: Work is done by a force on an object when the object moves in the direction of the force. This is because work is defined as the product of the force applied to an object and the distance over which the force is applied. When the object moves in the direction of the force, the force contributes to the displacement of the object, resulting in work being done. If the object moves perpendicular to the force, no work is done because the force does not contribute to the displacement. Moving against the force also results in work being done as the force is causing the displacement. The vertical movement of the object does not determine whether work is done; it is the alignment of the force with the object's displacement that matters. The duration of force application does not impact whether work is done; as long as the force causes the object to move in its direction, work is being done.