Nokea
What is the building block of RNA?
- A. Amino acid
- B. Nucleotide
- C. Protein
- D. Fatty acid
Correct Answer: B
Rationale: Nucleotide: Nucleotides are the building blocks of RNA. A nucleotide consists of a nitrogenous base (adenine, guanine, cytosine, or uracil in RNA), a sugar (ribose in RNA), and a phosphate group. A) Amino acid: Amino acids are the building blocks of proteins, not RNA. C) Protein: Proteins are made up of amino acids, not nucleotides. D) Fatty acid: Fatty acids are components of lipids, not RNA.
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What is the process by which a fertilized egg implants itself in the lining of the uterus?
- A. Fertilization
- B. Implantation
- C. Gestation
- D. Parturition
Correct Answer: B
Rationale: Implantation is the correct answer. It is the process where a fertilized egg attaches itself to the lining of the uterus to establish a pregnancy. Fertilization is the initial step where the sperm and egg fuse to form a zygote. Gestation refers to the period of fetal development within the uterus. Parturition is the process of giving birth and is not related to the implantation of the fertilized egg, which occurs earlier in the reproductive process.
Which structure, located between the pons and the spinal cord, plays a crucial role in coordinating movements, maintaining balance, and posture?
- A. Thalamus
- B. Medulla oblongata
- C. Cerebellum
- D. Hypothalamus
Correct Answer: C
Rationale: The correct answer is the cerebellum. The cerebellum, located between the pons and the spinal cord, is responsible for coordinating movements, maintaining balance, and posture. The thalamus functions in relaying sensory and motor signals to the cerebral cortex, the medulla oblongata controls vital autonomic functions such as breathing and heart rate, and the hypothalamus regulates various bodily functions like temperature and hunger. Therefore, the cerebellum is the structure that specifically handles coordination, balance, and posture.
Which of the following statements is true regarding a supersaturated solution?
- A. It is unstable and tends to crystallize
- B. It contains more solute than it could dissolve
- C. It has a higher concentration than a saturated solution
- D. It is rarely encountered in everyday solutions
Correct Answer: A
Rationale: A supersaturated solution is unstable and tends to crystallize because it contains more solute than it could dissolve at a given temperature. This excess solute is in a metastable state and can precipitate out if disturbed, leading to the formation of crystals. Option B is incorrect because a supersaturated solution does contain more solute than it could normally dissolve, but it becomes unstable due to this excess solute. Option C is incorrect because while a supersaturated solution does have a higher concentration than a saturated solution, the defining characteristic related to its instability is the excess solute. Option D is incorrect as supersaturated solutions can be encountered in various everyday scenarios, such as certain sugar solutions used in cooking or rock candy production.
Which organelle is responsible for packaging and secreting proteins into the extracellular space?
- A. Golgi apparatus
- B. Mitochondria
- C. Ribosomes
- D. Endoplasmic reticulum
Correct Answer: A
Rationale: A) Golgi apparatus: The Golgi apparatus is responsible for modifying, sorting, and packaging proteins into vesicles for secretion outside the cell or for use within the cell. It acts as a distribution and shipping department for the cell, ensuring proteins are properly processed and sent to their correct destinations like the extracellular space. Golgi apparatus is the correct answer because it directly handles the packaging and secretion of proteins.
B) Mitochondria: Mitochondria are known as the powerhouse of the cell and are responsible for generating energy in the form of ATP through cellular respiration. They are not involved in packaging and secreting proteins into the extracellular space.
C) Ribosomes: Ribosomes are responsible for protein synthesis, where they translate mRNA into proteins. They are not involved in packaging and secreting proteins into the extracellular space.
D) Endoplasmic reticulum: The endoplasmic reticulum (ER) plays a role in protein synthesis and folding, but it is the rough ER specifically that is involved in synthesizing proteins that are then transported to the Golgi apparatus for further processing and packaging. The Golgi apparatus is primarily responsible for packaging and secreting proteins, making it the correct answer for this question.
What happens to the acceleration of an object when the force acting on it is increased, assuming the mass remains constant?
- A. Acceleration increases
- B. Acceleration decreases
- C. Acceleration remains constant
- D. Acceleration becomes zero
Correct Answer: A
Rationale: According to Newton's second law of motion, acceleration is directly proportional to the force acting on an object when the mass is constant. Therefore, if the force acting on an object is increased while the mass remains constant, the acceleration of the object will also increase. This relationship is described by the formula F = ma, where F is the force applied, m is the mass of the object, and a is the acceleration. When force increases, acceleration increases, and vice versa, as long as the mass stays the same. Choice B (Acceleration decreases) is incorrect because acceleration and force have a direct relationship. Choice C (Acceleration remains constant) is incorrect because acceleration changes in response to changes in force. Choice D (Acceleration becomes zero) is incorrect because increasing force does not make acceleration zero; it actually increases it.