Nokea
What enzymes do lysosomes contain, leading to their nickname as the cell's 'suicide bags'?
- A. Hydrolytic enzymes
- B. Ligases (bonding enzymes)
- C. Transferases (molecule transfer)
- D. Oxidoreductases (redox reactions)
Correct Answer: A
Rationale: Lysosomes are organelles filled with hydrolytic enzymes that break down proteins, nucleic acids, lipids, and carbohydrates. These enzymes aid in digesting cellular waste and foreign substances, hence the term 'suicide bags' due to their involvement in cell degradation and recycling. Ligases are enzymes that catalyze the joining of two large molecules by forming a new chemical bond, not present in lysosomes. Transferases are enzymes that catalyze the transfer of functional groups from one molecule to another, not found in lysosomes. Oxidoreductases are enzymes involved in oxidation-reduction reactions, which are not the primary function of lysosomes.
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Which property of matter refers to the force of gravity acting on an object?
- A. Mass
- B. Weight
- C. Density
- D. Volume
Correct Answer: B
Rationale: Weight is the property of matter that refers to the force of gravity acting on an object. Mass is the amount of matter in an object, not affected by gravity. Density is the mass per unit volume of a substance, not directly related to gravity. Volume is the amount of space that an object occupies, not a measure of gravity's force.
What does the concept of punctuated equilibrium suggest?
- A. Evolution occurs gradually through the continuous accumulation of small changes over long periods.
- B. Evolution is characterized by long periods of relative stasis punctuated by rapid bursts of evolutionary change.
- C. The fossil record is a complete and accurate representation of all past life forms.
- D. Natural selection primarily favors extreme phenotypes within a population.
Correct Answer: B
Rationale: Punctuated equilibrium suggests that evolution is characterized by long periods of relative stasis punctuated by rapid bursts of evolutionary change. This concept, proposed by Stephen Jay Gould and Niles Eldredge, implies that species remain relatively unchanged for extended periods, followed by sudden bursts of rapid evolution. Option A describes the gradualism model, which is different from punctuated equilibrium. Option C is inaccurate as the fossil record is incomplete and biased. Option D is unrelated to the concept of punctuated equilibrium.
What is the difference between homologous chromosomes and sister chromatids?
- A. Homologous chromosomes have the same genes but may have different alleles, while sister chromatids are identical copies of the same chromosome.
- B. Homologous chromosomes are only found in diploid cells, while sister chromatids are found in both haploid and diploid cells.
- C. Both homologous chromosomes and sister chromatids are genetically identical, but only sister chromatids separate during mitosis.
- D. Both homologous chromosomes and sister chromatids can separate during mitosis, but only homologous chromosomes have different alleles.
Correct Answer: A
Rationale: Rationale:
- Homologous chromosomes are pairs of chromosomes that have the same genes in the same order, one from each parent. While they carry the same genes, they may have different alleles (variants of a gene).
- Sister chromatids are exact copies of each other, formed during DNA replication. They are held together by a centromere and are produced during the S phase of the cell cycle.
- During meiosis, homologous chromosomes pair up and exchange genetic material through crossing over, leading to genetic variation. Sister chromatids separate during mitosis to ensure each daughter cell receives an identical copy of the genetic material.
How does an unbalanced force affect an object at rest?
- A. It maintains the object's state of rest
- B. It does not affect the object's rest
- C. It moves the object into motion
- D. It decreases the object's mass
Correct Answer: C
Rationale: An unbalanced force acting on an object at rest will cause the object to move into motion. This is in accordance with Newton's first law of motion, which states that an object at rest will remain at rest unless acted upon by an external force. Therefore, option C, 'It moves the object into motion,' is the correct answer. Choices A and B are incorrect because an unbalanced force disrupts the object's state of rest. Choice D is incorrect as force does not affect the mass of an object.
Scoliosis is a condition characterized by abnormal lateral curvature of the spine. Which part of the spine is most commonly affected?
- A. Cervical spine (neck)
- B. Thoracic spine (upper back)
- C. Lumbar spine (lower back)
- D. All of the above
Correct Answer: B
Rationale: Scoliosis most commonly affects the thoracic spine, which is the upper back region. While scoliosis can potentially affect any part of the spine, the thoracic spine is the most frequently involved area. This region is more commonly affected due to the natural structural curves of the spine and the biomechanics of the thoracic area. The cervical spine (neck) and lumbar spine (lower back) can also be affected by scoliosis, but the thoracic spine is the primary area of involvement in most cases. Therefore, the correct answer is B, as it is the part of the spine most commonly affected by scoliosis.