Study guides › B/B › Biology
Reproduction & Development
From gamete formation to aging, this chapter follows one life. You will compare sperm and egg production, read the menstrual cycle hormone curves, trace fertilization through gastrulation, and connect each germ layer to the organs it forms.
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What this chapter covers
- Gametogenesis & the Male Reproductive System. Sperm and egg production differ in timing, arrest points, and products. Exam questions love the chromosome count at each stage.
- The Female System & the Menstrual Cycle. Know the hormone curves by heart: what peaks when, and why estrogen switches from negative to positive feedback.
- Fertilization, Cleavage & Implantation. Follow the embryo from sperm entry to implantation, and learn what hCG does and why the placenta takes over.
- Gastrulation, Germ Layers & Organogenesis. Every tissue traces back to one of three germ layers. Know the derivatives, especially the confusing ones like the adrenal gland.
- Differentiation, Developmental Control & Aging. Cells differ because they use different genes, not because they hold different DNA. Signals, gradients, and cell death shape the body.
Key points to know
- Oocyte arrests: prophase I until puberty, then metaphase II until fertilization
- Sertoli cells: support sperm, inhibin; Leydig cells: testosterone
- LH surge triggers ovulation; high sustained estrogen triggers the LH surge
- Progesterone from the corpus luteum peaks in the luteal phase
- Acrosomal reaction: enzymes digest the zona pellucida
- Cortical reaction hardens the zona: the slow block to polyspermy
- Gastrulation makes ectoderm, mesoderm, and endoderm
- Notochord induces the neural plate; neural crest becomes PNS, melanocytes, adrenal medulla
Try a practice question
Which cells of the testis secrete testosterone?
- Sertoli cells
- Leydig cells
- Spermatogonia
- Epididymal cells
Show the answer
B. Leydig (interstitial) cells respond to LH by making testosterone. Sertoli cells respond to FSH and testosterone and secrete inhibin, so they are the tempting wrong answer.
Common questions
What does this chapter cover?
Reproduction & Development covers Gametogenesis & the Male Reproductive System, The Female System & the Menstrual Cycle, Fertilization, Cleavage & Implantation, Gastrulation, Germ Layers & Organogenesis, Differentiation, Developmental Control & Aging.
What should I know first?
Oocyte arrests: prophase I until puberty, then metaphase II until fertilization Sertoli cells: support sperm, inhibin; Leydig cells: testosterone LH surge triggers ovulation; high sustained estrogen triggers the LH surge
24 original practice questions accompany this chapter in the app. Spaced review brings missed ideas back at the right time; it helps memory but cannot promise you will not miss an idea again.