State the letter(s) of the arrow or arrows that show mitosis.
Name cells W, X and Y.
On the sector shown in Fig. 4.2, use label lines and letters to identify: G a cell in the germinal epithelium M a maturing sperm cell Y an area where spermatids are found.
Describe the effect of increased temperature on the fertility of normal male worms.
Compare the effect of increased temperature on the fertility of alg-3 mutant male worms with the effect on fertility of alg-4 mutant male worms.
An investigation found that at $20^\circ\text{C}$ the number of spermatids produced in worms with both mutations, in alg-3 and alg-4, was the same as in normal worms. At $25^\circ\text{C}$, however, these mutant worms produced $29\%$ fewer spermatids than the normal worms. Microscopic study of their testes showed that many of the secondary spermatocytes had not completed meiosis. Use this information to state the letter of one arrow on Fig. 4.1 that represents a stage of spermatogenesis affected by mutations in both the alg-3 and alg-4 genes.
Table 4.2 gives the effect of temperature on the percentage of spermatids that achieved full motility at $20^\circ\text{C}$ and $25^\circ\text{C}$ in normal worms and in worms with mutations in both alg-3 and alg-4. With reference to Table 4.2, and the information in (iii), state the cause or causes of reduced fertility in these mutant worms at each temperature. at $20^\circ\text{C}$ at $25^\circ\text{C}$
An investigation found that at $20\,^{\circ}\text{C}$ the number of spermatids produced in worms with both mutations, in $alg\text{-}3$ and $alg\text{-}4$, was the same as in normal worms. At $25\,^{\circ}\text{C}$, however, these mutant worms produced $29\%$ fewer spermatids than the normal worms. Microscopic study of their testes showed that many of the secondary spermatocytes had not completed meiosis. Use this information to state the letter of one arrow on Fig. 4.1 that represents a stage of spermatogenesis affected by mutations in both the $alg\text{-}3$ and $alg\text{-}4$ genes.
Table 4.2 gives the effect of temperature on the percentage of spermatids that achieved full motility at $20\,^{\circ}\text{C}$ and at $25\,^{\circ}\text{C}$ in normal worms and in worms with mutations in both $alg\text{-}3$ and $alg\text{-}4$. With reference to Table 4.2, and the information in (iii), state the cause or causes of reduced fertility in these mutant worms at each temperature. at $20\,^{\circ}\text{C}$ at $25\,^{\circ}\text{C}$