Advertisements
Advertisements
Question
Give scientific reasons: Mature erythrocytes in humans lack nucleus and mitochondria
Advertisements
Solution
In case of fertilisation of the ovum by a sperm, the corpus luteum persists and continues to secrete progesterone in the body thus maintaining its high levels. The presence of progesterone prevents the maturation of another ovum, thus temporally stopping the menstrual cycle.
APPEARS IN
RELATED QUESTIONS
State the changes that take place in the uterus when Implantation of embryo has occurred
The diagram shown below is the longitudinal section of a testis of man. Study it carefully and answer the questions that follow
(i) Label the parts numbered 1 to 3 in the diagram.
(ii) In which part of the testis are the sperms produced?
(iii) State the functions of the parts labelled 1 and 3 in the diagram.
What do the ovaries in a woman produce?
What is the name of the process in which thickened uterus lining alongwith blood vessels is removed from the body of a human female through vaginal bleeding?
How long does a human baby take to develop before birth?
The normal body cell of an organism contains 28 pairs of chromosomes. The number of chromosomes present in its germ cell will be
(a) 28
(b) 14
(c) 56
(d) 42
When a human female reaches a certain age then vaginal bleeding occurs for a few days after regular time intervals.
(a) What is this process known as (i) in scientific terms, and (ii) in everyday language?
(b) At what approximate age this process starts in human females? When is the human female said to have attained at this stage?
(c) After how much time is this process repeated? For how many days does this process usually last?
(d) What does the onset of this process in human females signify?
(e) At which particular event in the life of a human female does this process stop temporarily but start again?
(f) At which approximate age of human female does this process stop permanently?
List two changes observed in girls at the time of puberty.
“Gender of child is determined by the male partner of couple”. Draw a diagram explaining the above statement.
Define the four stages in the uterine cycle.
