Nokea
During embryonic development, all tissues originate from
- A. Epithelial tissue only
- B. Muscle tissue only
- C. Connective tissue only
- D. Embryonic germ layers
Correct Answer: D
Rationale: During embryonic development, all tissues originate from the three primary germ layers: ectoderm, mesoderm, and endoderm. These germ layers give rise to various tissues and organs in the developing embryo through a process called gastrulation. Epithelial, muscle, and connective tissues are derived from these germ layers during development. Therefore, choices A, B, and C are incorrect as tissues do not originate from a single type of tissue but rather from the embryonic germ layers which differentiate into various tissues and organs.
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What tool helps scientists identify and classify organisms based on their shared characteristics?
- A. Binomial nomenclature
- B. Cladistics
- C. Dichotomous key
- D. Domain-based classification
Correct Answer: C
Rationale: A) Binomial nomenclature is a system used to give each organism a two-part scientific name (genus and species) but does not help in identifying or classifying organisms based on shared characteristics. B) Cladistics is a method of classification based on evolutionary relationships and shared characteristics, but it is not a tool used for identifying organisms. C) A dichotomous key is a tool that helps scientists identify and classify organisms based on their shared characteristics by presenting a series of choices leading the user to the correct identification. D) Domain-based classification is a system of grouping organisms into three domains (Bacteria, Archaea, Eukarya) based on molecular and genetic similarities, but it is not a tool used for identifying organisms based on shared characteristics.
During antibiotic use, bacteria can evolve resistance. This is an example of:
- A. Coevolution (two species influencing each other's evolution)
- B. Convergent evolution (unrelated organisms evolving similar traits)
- C. Macroevolution (large-scale evolutionary change)
- D. Artificial selection acting on a natural process
Correct Answer: D
Rationale: The process of bacteria evolving resistance to antibiotics due to the selective pressure exerted by the antibiotics is an example of artificial selection (human intervention selecting for certain traits) acting on a natural process (bacterial evolution). Antibiotic use creates a selective pressure that favors the survival and reproduction of bacteria with resistance traits, leading to the evolution of antibiotic-resistant strains.
- Coevolution (option A) refers to the influence of two species on each other's evolution, which is not the case in the scenario described in the question.
- Convergent evolution (option B) involves unrelated organisms evolving similar traits due to similar environmental pressures, which is not directly applicable to the situation of bacteria evolving resistance to antibiotics.
- Macroevolution (option C) refers to large-scale evolutionary changes over long periods, which is not specifically demonstrated in the context of bacteria evolving resistance during antibiotic use.
A ball is thrown horizontally off a cliff. Which of the following forces is responsible for its downward motion?
- A. The force of throwing
- B. Normal force from the air
- C. Tension force from the string (if used)
- D. Gravitational force
Correct Answer: D
Rationale: The gravitational force is responsible for the downward motion of the ball. When the ball is thrown horizontally off a cliff, the only force acting on it in the vertical direction is the force of gravity, which pulls the ball downward towards the ground. The other forces mentioned (force of throwing, normal force from the air, tension force from the string) do not contribute to the ball's downward motion in this scenario. The force of throwing initiates the horizontal motion, the normal force from the air opposes the ball's motion through air resistance, and tension force from the string would only be relevant if a string were attached to the ball. Therefore, gravitational force is the primary force responsible for the ball's downward motion in this situation.
What is the difference between a homozygous recessive genotype and a homozygous dominant genotype?
- A. Both have the same phenotype, but different genotypes.
- B. Both have the same genotype, but different phenotypes.
- C. Homozygous recessive has two dominant alleles, while homozygous dominant has two recessive alleles.
- D. Homozygous recessive has two identical recessive alleles, while homozygous dominant has two identical dominant alleles.
Correct Answer: D
Rationale: - Homozygous recessive genotype refers to an individual having two identical recessive alleles for a particular gene (e.g., rr for a trait where r represents the recessive allele).
- Homozygous dominant genotype refers to an individual having two identical dominant alleles for a particular gene (e.g., RR for a trait where R represents the dominant allele).
- The difference between the two genotypes lies in the specific alleles present in each case, with homozygous recessive having two recessive alleles and homozygous dominant having two dominant alleles.
- This genetic difference results in different phenotypes being expressed, as the dominant allele typically masks the expression of the recessive allele in heterozygous individuals.
Neurons, the functional units of the nervous system, belong to which tissue type?
- A. Epithelial tissue
- B. Connective tissue
- C. Muscle tissue
- D. Nervous tissue
Correct Answer: D
Rationale: Neurons are the functional units of the nervous system and are specialized cells that transmit nerve impulses. They belong to nervous tissue, which is the primary tissue type of the nervous system. Nervous tissue is composed of neurons and supporting cells called neuroglia. Choices A, B, and C are incorrect because epithelial tissue functions mainly in covering and lining body surfaces, connective tissue provides support and structure, and muscle tissue is responsible for movement. Neurons, being the basic functional units of the nervous system, are specifically classified under nervous tissue.