Nokea
Which process allows for the movement of large molecules, such as proteins and polysaccharides, across the cell membrane?
- A. Endocytosis
- B. Exocytosis
- C. Active transport
- D. Facilitated diffusion
Correct Answer: A
Rationale: Endocytosis is the process by which cells engulf large molecules or particles by wrapping the cell membrane around them to form a vesicle that is brought into the cell. This mechanism facilitates the movement of large molecules like proteins and polysaccharides across the cell membrane. Exocytosis involves the release of large molecules or particles from the cell, opposite to the scenario described in the question. Active transport requires energy to move molecules against their concentration gradient and is not primarily used for transporting proteins and polysaccharides. Facilitated diffusion entails the movement of molecules aided by transport proteins but is not the primary mechanism for transporting large molecules such as proteins and polysaccharides.
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Which of the following is NOT a source of genetic variation in a population?
- A. Mutations in genes
- B. Genetic drift (random fluctuations in allele frequencies)
- C. Gene flow (movement of genes between populations)
- D. Blending inheritance (traits of parents are averaged in offspring)
Correct Answer: D
Rationale: Rationale:
A) Mutations in genes: Mutations are changes in the DNA sequence that can introduce new alleles into a population, leading to genetic variation.
B) Genetic drift (random fluctuations in allele frequencies): Genetic drift refers to random changes in allele frequencies in a population, which can lead to genetic variation through chance events.
C) Gene flow (movement of genes between populations): Gene flow occurs when individuals move between populations, bringing new alleles with them and increasing genetic variation within populations.
D) Blending inheritance (traits of parents are averaged in offspring): Blending inheritance was a historical theory that suggested offspring inherit a blend of traits from their parents, leading to a reduction in genetic variation over time. However, this concept has been disproven by the understanding of Mendelian genetics, where traits are inherited independently and do not blend together.
Therefore, blending inheritance does not contribute
Which of the following represents a form of potential energy?
- A. A moving car
- B. A spinning top
- C. A raised hammer
- D. A rolling ball
Correct Answer: C
Rationale: A raised hammer represents potential energy as it possesses stored energy due to its position above the ground. When the hammer falls, this potential energy is converted into kinetic energy as it moves. In contrast, options A, B, and D involve objects already in motion, representing kinetic energy. Choice A, a moving car, is in motion and has kinetic energy. Choice B, a spinning top, is also in motion and exhibits kinetic energy. Choice D, a rolling ball, is already moving and thus has kinetic energy. Therefore, only choice C, a raised hammer, is the correct representation of potential energy among the given options.
What is the role of DNA in heredity?
- A. Provides energy for the cell
- B. Determines the structure and function of proteins
- C. Stores and transmits genetic information
- D. Controls cell division
Correct Answer: C
Rationale: DNA (deoxyribonucleic acid) is a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all living organisms. It stores genetic information in the form of a code made up of four chemical bases: adenine (A), thymine (T), cytosine (C), and guanine (G). This genetic information is passed down from parents to offspring and is responsible for determining an organism's traits and characteristics. DNA's primary role is to store and transmit genetic information, making option C the correct answer. DNA does not provide energy for the cell (option A), determine the structure and function of proteins (option B), or control cell division (option D).
Which hormone plays a key role in stimulating the release of milk from breast tissue after childbirth?
- A. Follicle-stimulating hormone (FSH)
- B. Luteinizing hormone (LH)
- C. Prolactin
- D. Estrogen
Correct Answer: C
Rationale: Prolactin is the hormone responsible for stimulating the release of milk from breast tissue after childbirth. It is produced by the pituitary gland and plays a crucial role in lactation. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are involved in the menstrual cycle and reproductive processes, not milk production. Estrogen is a female sex hormone with various functions but is not directly involved in milk production.
Which of the following is NOT a function of the skeletal system?
- A. Support and structure
- B. Production of red blood cells
- C. Storage of minerals like calcium
- D. Insulation of the body
Correct Answer: D
Rationale: The skeletal system's primary functions include support and structure, protection of internal organs, movement facilitation, production of blood cells, and storage of minerals like calcium. Insulation of the body is not a function of the skeletal system. Insulation, typically involving fat under the skin, helps regulate body temperature but is not a direct function of the skeletal system. Choice B, the production of red blood cells, is a function of the skeletal system as it occurs in the bone marrow within the bones. Choices A and C are also correct functions of the skeletal system.