An organism that reproduces sexually has a diploid number of 30. how many chromosomes will a gamete of this organism have?

Gamete of organism has a haploid number of chromosomes.

2n = 30
n = 15

A diploid cell containing 30 chromosomes will result in 15 chromosomes in each of the 4 daughter cells after meiosis occurs.

After first nuclear and cellular division (Meiosis I), each daughter cell will only have 15 chromosomes as homologous chromosomes are broken apart at Anaphase I of meiosis I. Chromosomal number is halved. After the second nuclear and cellular division (Meiosis II), each daughter cell will also have 15 chromosomes. This time, instead of the chromosomal number being halved, their chromosomal contents are halved. Sister chromatids are separated at Anaphase II of Meiosis II, resulting in daughter chromosomes each.

Hope this helps! :)

Spherical shaped cell might increase the surface area and decrease the volume.