Explanation:
A mature embryo sac (female gametophyte) in angiosperms is 7-celled but 8-nucleate: 3 antipodal cells (3 nuclei), 2 synergids (2 nuclei), 1 egg cell (1 nucleus), and 1 central cell with 2 polar nuclei. Thus total 8 haploid nuclei. The central cell is homodiploid (2 polar nuclei). Double fertilization involves these nuclei. This is typical of Polygonum type of development.
Explanation:
Functional residual capacity (FRC) is the volume of air in the lungs at the end of a normal expiration (ERV + RV). It prevents alveolar collapse and buffers gas concentrations. Vital capacity is max exhaled after max inhalation, total lung capacity is max air lungs can hold, inspiratory capacity is max inhaled after normal exhalation.
Consider the following statements about the human heart:
1. The right atrium receives blood from the vena cavae.
2. The left ventricle pumps blood to the lungs.
3. The septum separates the left and right sides.
Which of the above is/are correct?
Explanation:
The right atrium receives deoxygenated blood; the left ventricle pumps to the body (not lungs). Septum divides the heart. So 2 is incorrect.
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