Q61. Which vitamin is produced by skin exposure to sunlight?
Correct: Vitamin D
UV light converts cholesterol in skin to vitamin D.
Q62. What is the process by which organisms maintain internal stability?
Correct: Homeostasis
Homeostasis regulates internal conditions like temperature and pH.
Q63. Which type of bond holds DNA strands together?
Correct: Hydrogen bond
Hydrogen bonds between base pairs stabilize the DNA double helix.
Q64. What is the primary function of the circulatory system?
Correct: Transport nutrients and oxygen
The circulatory system delivers essential substances to cells.
Q65. Which hormone regulates blood sugar levels?
Correct: Insulin
Insulin lowers blood glucose by promoting uptake into cells.
Q66. What is the term for a group of organisms of the same species?
Correct: Population
A population consists of individuals of one species in an area.
Q67. Which process converts nitrogen gas to usable forms?
Correct: Nitrogen fixation
Bacteria convert atmospheric nitrogen to ammonia.
Q68. What is the main component of plant cell walls?
Correct: Cellulose
Cellulose provides rigidity and support to plant cells.
Q69. Which organ filters blood in the human body?
Correct: Kidney
Kidneys remove waste and excess substances from blood.
Q70. What is the study of fossils called?
Correct: Paleontology
Paleontology examines prehistoric life through fossils.
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