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Which of the following demonstrates a chemical reaction involving water?

  • A. Water and oil separate when combined
  • B. Water boils to produce steam at 100 degrees Celsius
  • C. Water dissolves sugar
  • D. Water produces gas when reacting with sodium metal
Correct Answer: D

Rationale: The correct answer is D because when water reacts with sodium metal, it produces hydrogen gas, indicating a chemical reaction. Options A, B, and C involve physical changes or processes like separation, phase change, and dissolution, respectively, which do not involve a chemical reaction. In option A, oil and water separating is a physical change due to differences in polarity. Option B describes a physical change where water undergoes a phase change from liquid to gas. Option C involves a physical change as sugar dissolves in water through a physical process without a chemical reaction occurring.

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Which of the following correctly orders structures from simple to complex?

  • A. Cells, tissues, atoms, organs
  • B. Atoms, cells, tissues, organs
  • C. Atoms, organs, tissues, cells
  • D. Organs, tissues, cells, atoms
Correct Answer: B

Rationale: The correct order of structures from simple to complex is atoms, cells, tissues, and organs. Atoms are the fundamental units of matter. Cells are the basic units of life composed of atoms. Tissues are formed by groups of cells working together. Organs consist of different tissues functioning together for specific purposes. Therefore, the correct sequence goes from the simplest structure, atoms, to the most complex structure, organs.

Which of the following structures is a mass within the ovary that secretes hormones to maintain the uterine lining during pregnancy?

  • A. Oviduct
  • B. Umbilical cord
  • C. Oocyte
  • D. Corpus luteum
Correct Answer: D

Rationale: The correct answer is the corpus luteum. The corpus luteum is a temporary endocrine structure in the ovary that forms after ovulation. It secretes hormones, primarily progesterone, which are essential to maintain the uterine lining during pregnancy. The other options, such as the oviduct, umbilical cord, and oocyte, do not have the function of secreting hormones to support the uterine lining in pregnancy.

The covalent bonds between the monomers of an enzyme macromolecule are

  • A. phosphodiester bonds
  • B. glycosidic bonds
  • C. ester bonds
  • D. peptide bonds
Correct Answer: D

Rationale: Enzymes are proteins, and proteins are made up of amino acid monomers linked together by peptide bonds. Therefore, the covalent bonds between the monomers of an enzyme macromolecule are peptide bonds.

What is the atomic number of an atom that has 12 protons and 12 neutrons?

  • A. 1
  • B. 144
  • C. 12
  • D. 24
Correct Answer: C

Rationale: The atomic number of an element is determined by the number of protons in its nucleus. In this case, the atom has 12 protons, which directly corresponds to its atomic number. Neutrons have no impact on the atomic number; they contribute to the atomic mass. The atomic number uniquely identifies an element based on the number of protons in its nucleus. Therefore, the correct answer is 12, as it represents the number of protons in the nucleus and defines the element, regardless of the presence of neutrons.

In pea plants, green pod color (G)is dominant to yellow pod color (g). A cross was done between a plant with green pods and plant with yellow pods. Of the resulting offspring. 50% had green pods and 50% had yellow pods. Which of the following we the genotypes of both present plants?

  • A. GG X GG
  • B. Gg × gg
  • C. Gg × gg
  • D. Gg × Gg
Correct Answer: D

Rationale: The 50% green and 50% yellow offspring suggests that one parent was heterozygous (Gg) and the other was homozygous recessive (gg), leading to a 1:1 ratio of green to yellow.

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