221: In which one of the following kinds of organisms is the phenomenon found wherein the female kills the male after copulation?
(a) Spider
(b) Honeybee
(c) Dragonfly
(d) Pit viper
Explanation:
Sexual cannibalism is a special case of cannibalism in which a female organism kills and consumes a male of the same species before, during, or after copulation. Rarely, these roles are reversed.
Although other forms of cannibalism are widespread in the animal kingdom, sexual cannibalism has been documented only in arachnids, insects and amphipods although anecdotal evidence suggests its existence in gastropods and copepods as well.
Despite its overall rarity, sexual cannibalism is common in many families of spiders and scorpions, and can have important effects on population size and sex ratio. Among insects, sexual cannibalism is a nearly universal habit among mantids but is otherwise rare. In most species in which it occurs, sexual cannibalism is related to the larger size of the female due to sexual dimorphism Some scientists have down played the significance of sexual cannibalism. Stephen Jay Gould argued that sexual cannibalism was too rare to be significant and said biologists had become "overzealous about the power and range of selection by trying to attribute every significant form and behavior to its direct action." Subsequent research contradicted this opinion and shows that for some sexually cannibalistic species, males are a significant food source for females. One study estimated that 63 percent of the diet of female Chinese mantids are the males of the species.
222: Of the four landmarks in medical history given below, which one was the first to take place ?
(a) Organ transplant
(b) Bypass surgery
(c) Test-tube baby
(d) Plastic surgery
Explanation:
Plastic Surgery. It is one of the ancient surgical techniques also especially plastic surgery, in ancient India, was developed far beyond anything known elsewhere at the time. In this respect Indian surgery remained ahead of European until the 18th century, when the Surgeons of East India Company learned the art of rhinoplasty from the Indians. Remaining three surgical techniques are of recent origin.
223: Regarding the atom of a chemical element, the magnetic quantum number refers to
(a) orientation
(b) shape
(c) size
(d) spin
224: Living organisms require at least 27 elements of which 15 are metals. Among these, those required in major quantities include
(a) Potassium, Manganese, Molybdenum & Calcium
(b) Potassium, Molybdenum, Copper & Calcium
(c) Potassium, Sodium, Magnesium & Calcium
(d) Sodium, Magnesium, Copper & Manganese
Explanation:
Minerals required in macroquantities are Carbon, Hydrogen, Oxygen, Nitrogen, Calcium, Phosphorus, Potassium, Sodium, Chlorine, Sulphur and Magnesium.
Micro nutrients or trace elements which are required in smaller quantities : Iron, Manganese, Zinc, Copper, Iodine, Cobalt, Molybdenum, Selenium, Chromium and Silicon.
225: Which one of the following is an insectivorous plant?
(a) Passion flower plant
(b) Pitcher plant
(c) Night queen
(d) Flame of the forest
Explanation:
Insectivorous plants (Carnivorous plants) are plants that derive some or most of their nutrients (but not energy) from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs and rock outcroppings.
Five basic trapping mechanisms are found in carnivorous plants.
1. Pitfall traps (pitcher plants) trap prey in a rolled leaf that contains a pool of digestive enzymes or bacteria.
2. Flypaper traps use a sticky mucilage.
3. Snap traps utilize rapid leaf movements.
4. Bladder traps suck in prey with a bladder that generates an internal vacuum.
5. Lobster-pot traps force prey to move towards a digestive organ with inward pointing hairs.