Biology Questions and Answers
- What is the normal
duration of the menstrual
cycle? How does the calendar
contraceptive method work?
The normal cycle is 28 dduration ofays but it can vary amo the menstrualng (^)
different women or in different cyclesthe same woman. of
In the calendar the date n-14 (n minus 14) is takencontraceptive method
considering n the number of days of the
normal m(generally nenstrual cycle=28). The safety margi of the womann +3 (^)
or –3 refers to the days around n-14
that intprevent pregnancy. (ercourse should be avoided toThis method is not (^)
exempt from failures. A doctor must
alwaysany contraceptive be consulted bmethod.)efore relying on
- How is the ovulation date
estimated with the control of
the woman's body
temperature?
One method to estimate the ovulation day is daily control oexactf the (^)
body temperature taken always under
same conditions. At ththe body temperature e ovulation dayoften increases
about 0.5 degrees centigrade.
- What is the contraceptive
mechanism of the IUD?
The IUD (intrauterine device) is a piece
of plasticinserted within th coated with e uterus by a doctor.copper that is (^)
Copper is then gradually released (IUD
may lasta spermicidal action sp 5 to 10 years) aerm cells arnd since it hase
destroyed before fecundation. Besides
this mechanism the IUD inside the uterus causes slightmovement of the
endometrial inflammation that helps to
prevent nidation.
- Generally how does a male
animal realize that the female
is receptive to copulation?
In most vertebrate spfecundation the females hecies with intave ernal
reproductive cycles with fertile periods.
During this pepheromones (odoriferous substancesriod the female secretes
that attract the male of the species)
from thpresence of the male e skin and mucosae. Tindividual anhe (^) d his
pheromones also stimulates the release
of pheromones by animals also use pheromones forthe female. (Many
territorial demarcation and for signal
transmission bethe location of dangers antween individuals aboutd food.)
- What is parthenogenesis?
Parthenogenesis is the reproduction or
formation oegg cell but withof a new individual from theut fecundation by the (^)
male gamete. According to the species,
individuals bmay be male oorn by parthenogenesisr female, or of any sex.
In bees the drone (the single male is haploid and born by parthenogenesisbee)
while the females (queen and workers)
are diploid.
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