Nokea
Which type of muscle is characterized by involuntary contractions, is striated, and is primarily found in the heart?
- A. Skeletal muscle
- B. Smooth muscle
- C. Cardiac muscle
- D. Elastic muscle
Correct Answer: C
Rationale: The correct answer is C, Cardiac muscle. Cardiac muscle fits the description provided in the question as it exhibits involuntary contractions, striations, and is predominantly located in the heart. Skeletal muscle, while also striated, is voluntary and not involuntary like cardiac muscle. Smooth muscle lacks striations and is typically found in the walls of internal organs. Elastic muscle is not a recognized type of muscle tissue in human anatomy, making it an incorrect choice.
You may also like to solve these questions
How can a concave mirror be used?
- A. Focus light to a single point
- B. Create only virtual images
- C. Always magnify objects
- D. Scatter light
Correct Answer: A
Rationale: A concave mirror can be used to focus light to a single point. This property is known as converging light rays to a focal point. When light rays parallel to the principal axis strike a concave mirror, they converge at a specific point called the focal point. This ability to focus light makes concave mirrors useful in applications such as reflecting telescopes and shaving mirrors. Choice B is incorrect because concave mirrors can create both real and virtual images, depending on the object's position relative to the mirror. Choice C is incorrect as concave mirrors can magnify, reduce, or maintain the size of objects, depending on the object's position and the distance from the mirror. Choice D is incorrect as concave mirrors do not scatter light but instead have the ability to reflect and focus light to produce clear images.
In ecology, what defines a closed system?
- A. Exchanges energy but not matter
- B. Exchanges both energy and matter
- C. Exchanges neither energy nor matter
- D. Recycles nutrients efficiently
Correct Answer: A
Rationale: In ecology, a closed system is one that does not exchange matter with its surroundings but can exchange energy. This means that while energy can enter or leave the system, the amount of matter within the system remains constant. Option A correctly defines a closed system in ecology. Choices B and C are incorrect as a closed system does not exchange matter or energy. Option D is unrelated to the concept of a closed system in ecology.
Which part of the brain generates the rhythmic electrical activity responsible for brain waves?
- A. Cerebrum
- B. Thalamus
- C. Hypothalamus
- D. Reticular formation
Correct Answer: D
Rationale: The reticular formation is a network of neurons located in the brainstem that plays a crucial role in regulating arousal and consciousness. It generates the rhythmic electrical activity responsible for brain waves, which are measured using electroencephalography (EEG). The cerebrum, thalamus, and hypothalamus do not primarily generate brain waves; they have other specialized functions within the brain. The cerebrum is responsible for higher brain functions such as thinking and voluntary movements. The thalamus acts as a relay station for sensory information. The hypothalamus is involved in various functions such as regulating body temperature, hunger, and hormonal activities.
What is the main function of calcitonin, a hormone produced by the thyroid gland?
- A. Stimulate metabolism and heat production
- B. Increase calcium absorption from the intestines
- C. Enhance bone growth and development
- D. Lower blood calcium levels
Correct Answer: D
Rationale: Calcitonin is a hormone produced by the thyroid gland that primarily functions to lower blood calcium levels. It achieves this by inhibiting bone breakdown and promoting calcium excretion by the kidneys. Therefore, the correct answer is D as it reflects the main role of calcitonin in calcium homeostasis. Choices A, B, and C are incorrect as they do not align with the primary function of calcitonin. Calcitonin does not stimulate metabolism and heat production (Choice A), increase calcium absorption from the intestines (Choice B), or enhance bone growth and development (Choice C).
Where does gas exchange take place in the lungs?
- A. Bronchi
- B. Trachea
- C. Alveoli
- D. Pleura
Correct Answer: C
Rationale: Gas exchange in the lungs occurs in the alveoli. Alveoli are tiny air sacs where oxygen from inhaled air diffuses into the bloodstream, and carbon dioxide from the blood diffuses into the alveoli to be exhaled. The bronchi are the main airways that branch off from the trachea, which is the windpipe connecting the larynx to the bronchi. The pleura is a membrane surrounding the lungs and lining the chest cavity, providing protection and lubrication for the lungs but not directly involved in gas exchange.