Nokea
How does the human eye focus light?
- A. Cornea
- B. Iris
- C. Lens
- D. Retina
Correct Answer: C
Rationale: The human eye focuses light by adjusting the shape of its lens. The lens changes shape to allow the eye to focus on objects at different distances, a process known as accommodation. The cornea is the transparent outer covering of the eye that helps to focus light but does not change shape like the lens. The iris controls the size of the pupil to regulate the amount of light entering the eye. The retina is the light-sensitive layer at the back of the eye that receives and processes images but does not adjust the focus of light.
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The patella, commonly known as the kneecap, is an example of a:
- A. Sesamoid bone
- B. Long bone
- C. Short bone
- D. Irregular bone
Correct Answer: A
Rationale: The patella, also known as the kneecap, is an example of a sesamoid bone. Sesamoid bones develop within tendons, such as the patellar tendon in this case. The patella is embedded in the tendon of the quadriceps muscle, enhancing the mechanical advantage of the muscle and protecting the knee joint. Long bones, like the femur, are characterized by their elongated shape with growth plates at the ends. Short bones, such as those in the wrist and ankle, are cube-shaped bones. Irregular bones, like vertebrae, do not fit into the other bone shape categories due to their unique shapes and functions.
A person pushes a box across a floor with a constant force. The box eventually comes to a stop due to friction. What happens to the work done by the person?
- A. It increases as the box moves further.
- B. It decreases as the box slows down.
- C. It remains constant throughout the motion.
- D. It becomes zero once the box stops.
Correct Answer: D
Rationale: Work done is defined as the product of the force applied and the distance moved in the direction of the force. In this scenario, when the box comes to a stop, the displacement becomes zero, leading to zero work done by the person. Choice A is incorrect as the work done is not increasing, but rather decreasing as the box slows down. Choice B is incorrect because the work done does not decrease as the box slows down; it becomes zero when the box stops. Choice C is incorrect as the work done is not constant but decreases to zero when the box stops.
Which of the following is the main organ responsible for producing bile?
- A. Liver
- B. Gallbladder
- C. Pancreas
- D. Stomach
Correct Answer: A
Rationale: The liver is the main organ responsible for producing bile. Bile, a greenish-yellow fluid, is produced by the liver and stored in the gallbladder. Its primary function is to aid in the digestion and absorption of fats in the small intestine. When needed, the gallbladder releases bile into the small intestine to facilitate fat digestion. The pancreas produces digestive enzymes and insulin, not bile, making choice C incorrect. The stomach's primary role is to digest food through gastric juice secretion, making choice D incorrect. Therefore, the correct answer is the liver, as it is the main organ responsible for bile production.
What is the importance of RNA splicing?
- A. Removes introns from the mRNA molecule
- B. Adds the poly-A tail to the mRNA molecule
- C. Activates the mRNA molecule for translation
- D. Modifies the structure of the protein
Correct Answer: A
Rationale: RNA splicing is a crucial process in gene expression where non-coding regions called introns are removed from the pre-mRNA molecule, and the remaining coding regions called exons are joined together to form the mature mRNA molecule. This process ensures that only the protein-coding sequences are retained in the mRNA for translation, allowing for the production of functional proteins. Therefore, option A is the correct answer as it accurately describes the importance of RNA splicing in generating mature mRNA molecules for protein synthesis.
B) Adding the poly-A tail to the mRNA molecule is a post-transcriptional modification that occurs after RNA splicing and is not directly related to the process of removing introns.
C) Activating the mRNA molecule for translation is typically achieved through the addition of a 5' cap and the poly-A tail, rather than through RNA splicing.
D) Modifying the structure of the protein is not directly related to the process of RNA splicing, which primarily focuses on mRNA maturation by removing non-coding introns.
During micturition, the process involves a combination of:
- A. Gravity alone
- B. Voluntary muscle contractions only
- C. Involuntary muscle contractions only
- D. Both voluntary and involuntary muscle contractions
Correct Answer: D
Rationale: During micturition, which is the process of urination, both voluntary and involuntary muscle contractions are involved. Voluntary muscle contractions include the relaxation of the external urethral sphincter, allowing the release of urine, while involuntary muscle contractions involve the detrusor muscle in the bladder contracting to expel urine. Choices A, B, and C are incorrect because micturition is not solely dependent on gravity, voluntary muscle contractions, or involuntary muscle contractions alone. The correct answer is D as both types of muscle contractions are necessary for the complete process of urination.