Biology 9700 · AS & A Level · Passage of information from parents to offspring

Passage of information from parents to offspring — practice question

Spermatogenesis occurs within the seminiferous tubules of the testis. Fig. 4.1 is a diagram of some of the cells in a small region of a seminiferous tubule.
(a(i))[2]

On Fig. 4.1, indicate whether each labelled cell is haploid or diploid. Use $n$ if the cell is haploid and $2n$ if the cell is diploid.

(a(ii))[2]

Spermatogenesis includes meiosis, mitosis, growth and maturation. For each of the steps below, state which process is involved in spermatogenesis. spermatogonium to primary spermatocyte spermatid to spermatozoan (sperm)

(iii)[3]

Suggest why some people who oppose genetically modified insect-resistant maize or cotton might accept the growing of this genetically modified wheat.

(a(iii))[1]

State one function of a Sertoli cell.

(b)[4]

Outline the treatment that is needed to obtain mature oocytes as part of an IVF procedure.

(c(i))[4]

Using Table 4.1, describe how adding reproductive hormones affects spermatid development after 48 hours.

(c(ii))[1]

Suggest one reason for the apparent fall in the percentage of elongated cells between 24 hours and 48 hours in some samples.

(c(iii))[2]

Suggest why the culture medium was kept at $30\,^{\circ}\text{C}$ rather than at core body temperature ($37\,^{\circ}\text{C}$).

(ii)[1]

Suggest one reason for the apparent fall in the percentage of elongated cells between 24 hours and 48 hours in some samples.

Worked solution & mark scheme

This 20-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct ploidy assignment: spermatogonium $2n$, primary spermatocyte $2n$, secondary spermatocyte $n$, spermatids $n$, spermatozoa $n$

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