Which of the following is a characteristic feature of mammals?
A. Presence of mammary glands
B. Cold-blooded metabolism
C. Lay eggs only
D. Presence of feathers
Answer: Option A
Solution (By JKSSB Mock Tests)
Mammals are distinguished by the presence of mammary glands in females that secrete milk for nourishing young. They are warm-blooded, have hair/fur, and most give birth to live young (viviparous), though monotremes like platypus lay eggs. Feathers are characteristic of birds. Cold-blooded refers to ectotherms (reptiles, amphibians, fish). Mammals are endotherms.
Explanation:
Frederick Griffith in 1928 demonstrated the transformation of non-virulent pneumococci to virulent by heat-killed virulent strain, suggesting a transforming principle. Avery et al. later identified it as DNA. Hershey-Chase confirmed DNA is genetic material.
No comments yet. Be the first to start the discussion!