Answer:
Option (2).
Explanation:
Zygote is formed by the fusion of the male and female gamete during the process of sexual reproduction. The zygote undergoes further development inside the female womb.
The embryonic period starts from the third week after the conception. The important organs and structure development occur during the embryonic period. The formation of three germ layers occur in this period.
Thus, the correct answer is option (2)
Answer:
Explanation:
The cell membrane separates the cell from the outer environment. The extracellular fluid contains the sodium ions (Na+), chloride ions (Cl-), while intracellular fluid contains potassium (K +) and negative anions.
The potential difference arises when the membrane is selectively permeable to some ions. The resting potential is -70mV.
When the neurons get excited, the sodium ions start to enter by sodium channels.
Now there are more positive ions inside the cell membrane. It disturbs the resting potential i.e. -70mV. This stage is known as depolarization.
When the inside environment of the cell is more positively charged, the potassium ions start to move out of the cell. It goes out by the voltage-gated channels. Thus resting stage is maintained and it is known as repolarization.
But the initial stability of the cell membrane has to be maintained. To restore the resting stage, the sodium ions start to move out of the membrane and potassium ions enter into the cells again. This is an active transport and has done by the Na+ - K+ pump. Here 3 sodium ions move out and 2 potassium ions pumped into the cell through the plasma membrane.
Thus the resting potential regains. The potassium ions come back into the cells against the concentration gradient and ATP provides the energy for this phenomena.
The second one I believe.
D. Species with an odd number of chromosome sets (triploid and pentaploid) would be infertile.
E. Aneuploid individuals (monosomic and trisomic) would have reduced fertility.
Explanation - Chromosomes generally happens to occur in the set of two. Organism that have more than two sets of chromosome are called polyploids. Polyploids that have odd or uneven count of sets of chromosome are sterile or fully infertile.
Example - triploid (3n), pentaploid (5n) because their gametes and offsprings are aneuploid. Aneuploidy is addition of entire chromosome to the already existing normal set of chromosome. Aneuploids are unable to produce viable offspring because their fertility got decreased as the zygote formed after the fertilization itself is aneuploid.
