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प्रश्न
The diagram given below shows the early embryonic stages of fish, reptiles, birds and humans. Though adult reptiles, birds and mammals breathe air, their embryos possess gills. How does this fact support evolution?
उत्तर
Embryos show the presence of gills to prove that the ancestors were aquatic. The concept of “ontogeny recapitulates phylogeny”.
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संबंधित प्रश्न
During the reproductive cycle of a human female, when, where and how does a placenta develop? What is the function of placenta during pregnancy and embryo development?
(a) Arrange the following hormones in sequence of their secretion in a pregnant woman.
(b) Mention their source and the function they perform :
hcG, LH, FSH, Relaxin
Which of the following hormones is not secreted by human placenta?
Eye lens is formed from ______.
Which of the following hormones is not a secretory product of human placenta?
Urine test during pregnancy determines the presence of ______.
In the event of pregnancy, the corpus luteum persists under the influence of ______.
The concentration of which of the following substances will decrease in the maternal blood as it flows from embryo to placenta through the umbilical cord?
The human foetus within the uterus
- Oxygen
- Amino Acids
- Carbon dioxide
- Urea
Which of the following is not a function of the placenta?
Draw a diagram showing human foetus within the uterus and label any four, parts in it.
