Q36 / 200 · NEET 2008 (Screening) · Botany
Which one of the following pairs of plant structures has haploid number of chromosomes?
- AMegaspore mother cell and antipodal cells
- Correct answerBEgg cell and antipodal cells
- CNucellus and antipodal cells
- DEgg nucleus and secondary nucleus
Solution
In angiosperms a single diploid megaspore mother cell matures within an ovule. Through meiosis it gives rise to four megaspores (haploid). In most plants only one of these megaspores survive. This functional megaspore divides three times by mitosis and produces eight haploid nuclei enclosed within a 7-celled embryo sac. One nucleus is located near the opening of embryo sac in egg cell. Two nuclei are located in a single cell in the midde of embryo sac and are called polar nuclei, two nuclei are contained in cells called synergids that flank the egg cell and other three nuclei are resided in the cells called antipodals, located at the end of embryo sac, opposite the egg cell.
Nucellus is centrally located mass of thin-walled parenchymatous cells covered by integuments in ovule.
Hence, the correct answer is option: 'B'.