In angiosperm, the haploid, diploid and triploid structures of a fertilized embryo sac sequentially are:
Column-I | Column-II | ||
---|---|---|---|
(i) | First month | (a) | Separation of eye lids |
(ii) | Second month | (b) | Hairs on head |
(iii) | Fifth month | (c) | Heart |
(iv) | Six month | (d) | Limbs & digits |
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion (A) : 02 is liberated in the non-cyclic photophosphorylation.
Reason (R) : Liberation of oxygen is due to photolysis of water.
In the light of the above statements, choose the correct answer from the options given below
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion (A) : The Cro-Magnon man was the direct ancestor of the living modern man.
Reason (R) : Cro-Magnon man had slightly prognathous face.
In the light of the above statements, choose the correct answer from the options given below
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion (A) : In eukaryotes, transcription occurs in nucleus.
Reason (R) : In bacteria, transcription and translation occurs in cytoplasm.
In the light of the above statements, choose the correct answer from the options given below
A successful pregnancy goes through several distinct stages. A man’s sperm must reach, penetrate, and fertilize a woman’s egg.
Fertilization is the association of the female gamete (egg) and the male gamete (spermatozoa). Whether it occurs naturally inside the female reproductive system or with the help of reproductive technologies outside of the human body. Further, the product is a structure called a zygote.
After fertilization, the embryo is created from a small group of cells that are constantly splitting inside of a complex structure called the blastocyst. It is formed by two groups of cells, inner and outer cells, and fluids. The blastocyst remains inside a protective cover during maturation called zona pellucida, which could be described as an eggshell. The outer cells are located just below this cover, which will create the future placenta and surrounding tissues to support fetal development in the uterus.
When the blastocyst outreach the uterus it implants in the endometrium, the mucus membrane which lines the uterus. The external cells of the blastocyst and the uterine inner lining, altogether, create the future placenta. A structure that transfers nutrients to the baby and removes his/her wastes is called the placenta.
As the blastocyst reaches the final stage in the implantation process into the inner lining of the uterus, it evolves into a structure called an embryo. At this time, internal organs and external structures develop. The mouth, lower jaw, and throat are emerging, while the blood circulation system starts its evolution and a heart tube is created. The ears arise and arms, fingers, legs, toes, and eyes are being shaped. The spinal cord and the brain are already formed, while the digestive tract and sensory organs start their development. The cartilage is being replaced by the first bones.
The embryo moves into the final stage of development by the twelfth week of fertilization, called the fetal stage. Till now, the fetus has formed all of the organs and structures that are necessary for a baby, but those organs still need to grow and develop.