what is the building block of dna

ATI TEAS 7

ati teas 7 science

1. What is the building block of DNA?

A. Amino acid
B. Nucleotide
C. Phosphate group
D. Fatty acid

Correct answer: B

Rationale: - Amino acids are the building blocks of proteins, not DNA. - Nucleotide is the correct building block of DNA. A nucleotide consists of a sugar (deoxyribose in DNA), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). - The option 'C) Phosphate group' is incorrect as it is only part of a nucleotide, not the complete building block of DNA. - Fatty acids are not the building blocks of DNA; they are a type of lipid molecule.

2. What is the main function of the small intestine?

A. To store food and break it down into smaller pieces
B. To absorb nutrients into the bloodstream
C. To produce enzymes that help digest food
D. To eliminate waste products from the body

Correct answer: B

Rationale: The small intestine is a crucial part of the digestive system responsible for absorbing nutrients into the bloodstream. This absorption primarily occurs through the villi lining the small intestine, which increases the surface area available for nutrient absorption. Nutrients like carbohydrates, proteins, fats, vitamins, and minerals are absorbed into the bloodstream to support various bodily functions such as energy production, growth, and repair. Choices A, C, and D are incorrect as they do not accurately depict the primary function of the small intestine, which is nutrient absorption.

3. Which statement about white blood cells is true?

A. B cells are responsible for antibody production.
B. White blood cells are produced in the bone marrow before entering the bloodstream.
C. Platelets, a specialized class of blood cells, function to clot blood and stop bleeding.
D. The majority of white blood cells are active throughout life, providing immunity across all age groups.

Correct answer: A

Rationale: The correct answer is A: B cells, a type of white blood cell, are responsible for producing antibodies in response to pathogens. Antibodies play a crucial role in identifying and neutralizing foreign substances like bacteria and viruses in the body, aiding in the immune response and protecting against infections. This function is essential for maintaining a healthy immune system. White blood cells, including B cells, are produced in the bone marrow before entering the bloodstream. Platelets, not white blood cells, are a specialized class of blood cells that function to clot blood and stop bleeding. While white blood cells provide immunity, not all of them are active throughout life as some have specific lifespans and functions.

4. Which organ helps break down food by grinding it with your teeth?

A. Stomach
B. Esophagus
C. Liver
D. Mouth

Correct answer: D

Rationale: The correct answer is D: Mouth. The mouth is the organ that helps break down food by grinding it with your teeth. The process of chewing, also known as mastication, breaks down food into smaller pieces, making it easier to swallow and digest. The teeth in the mouth play a crucial role in this initial stage of digestion by physically breaking down food into smaller particles. The other options listed, such as the stomach, esophagus, and liver, do not directly participate in the mechanical breakdown of food through chewing. The stomach is responsible for further digestion through chemical processes, the esophagus is a muscular tube that helps transport food to the stomach, and the liver is primarily involved in metabolic functions and bile production.

5. What is the primary function of lymph nodes, small, bean-shaped structures found along lymphatic vessels?

A. To store excess lymph fluid
B. To produce red blood cells
C. To filter lymph and fight infection
D. To transport lymph to the heart

Correct answer: C

Rationale: Lymph nodes primarily function to filter lymph and fight infection. They contain immune cells that help to remove pathogens and foreign particles from the lymph fluid as it passes through the nodes. This process helps to activate the immune response and defend the body against infections. Choice A is incorrect as lymph nodes do not store excess lymph fluid; they filter lymph. Choice B is incorrect as the production of red blood cells primarily occurs in the bone marrow, not in lymph nodes. Choice D is incorrect as lymph nodes do not transport lymph to the heart; they filter and process lymph to remove impurities and activate the immune response.