IB HL Biology Key Things to Remember

Personally for Connor Jung in preparation for May 2025

Steps of Photosynthesis

• light-independent reactions in stroma of chloroplast

• using energy/ATP from light-dependent reactions

• Calvin cycle carries out light-independent reactions

• Cycle begins with a 5C compound (ribulose bisphosphate/RuBP)

• CO2 from atmosphere is fixed to RuBP

• catalyzed by Rubisco

• Two 3C compounds (aka glycerate-3-phosphate or G3P

• G3P is reduced

• Using electrons/hydrogen (atoms) from NADPH

• 2 triose phosphate (molecules) used to form a glucose

• Some triose phosphate molecules used to make more/regenerate RuBPand continue the cycle.

Entire Menstrual Cycle process

• follicle stimulating hormone (FSH) is secreted from the anterior pituitary and stimulates growth of ovarian follicles

• The dominant follicle produces estrogen, which inhibits FSH secretion via negative feedback to prevent other follicles growing

• idway through the cycle (~ day 12), estrogen concentrations reach a critical threshold which stimulates the anterior pituitary to release a large surge of luteinizing hormone (LH) and a lesser surge of FSH

• LH causes the dominant follicle to rupture and release an egg (secondary oocyte) – this is called ovulation

• The ruptured follicle develops into a corpus luteum that secretes high levels of progesterone, as well as lower levels of estrogen

• Estrogen and progesterone inhibit the further secretion of FSH and LH, preventing other follicles from developing while the corpus luteum is active

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