ati teas 7 science

Correct Answer: B

Rationale: Peristalsis is the correct answer. It is the term for the involuntary muscle contractions that move food through the digestive tract. These contractions help propel food along the digestive system. Segmentation is the process of breaking down food by mixing it with digestive juices. Chyme is the semi-fluid mass of partly digested food in the stomach and intestines. Emulsification is the breakdown of fats into smaller droplets for easier digestion. But none of these terms specifically refer to the muscle contractions that move food through the digestive tract like peristalsis does.

Correct Answer: B

Rationale: The primary function of red blood cells is to transport oxygen. They contain hemoglobin, which binds to oxygen in the lungs and delivers it to tissues throughout the body. This process is essential for cellular respiration and energy production. Choice A is incorrect because while red blood cells do transport nutrients, their main role is oxygen transport. Choice C is incorrect because fighting infection is primarily the role of white blood cells. Choice D is incorrect as red blood cells do not produce antibodies; that is the function of specialized white blood cells called B cells.

Correct Answer: A

Rationale: The correct answer is A: Nucleosome. Nucleosomes are the basic units of DNA packaging in eukaryotic cells, consisting of DNA wrapped around histone proteins. This structure helps in compacting the DNA to fit inside the nucleus. Choice B (Chromatin) is a broader term for DNA and associated proteins, not a specific packaging structure. Choice C (Histone) refers to the protein component of nucleosomes, not the packaging structure itself. Choice D (Centromere) is a region on a chromosome where the kinetochore forms during cell division, not involved in DNA packaging.

Correct Answer: B

Rationale: The correct answer is B: Nucleotide. Nucleotides are the building blocks of DNA, consisting of a sugar molecule, a phosphate group, and a nitrogenous base. They are linked together in a specific sequence to form the DNA molecule's double helix structure. Amino acids (choice A) are the building blocks of proteins, not DNA. Phosphate groups (choice C) are components of nucleotides but are not the sole building blocks of DNA. Fatty acids (choice D) are not involved in the structure of DNA at all. Therefore, the correct answer is nucleotide as it accurately represents the basic components that make up DNA.

Correct Answer: A

Rationale: The correct answer is A because the atomic number represents the number of protons in the nucleus of an atom, which determines the element's identity. The mass number is the total number of protons and neutrons in the nucleus, indicating the atom's mass. The number of electrons is not directly related to either the atomic or mass number, eliminating choices B and D. Choice C is incorrect because the atomic number specifically refers to the number of protons, not neutrons. Thus, choice A is the only accurate explanation of the difference between the atomic number and the mass number.