Free QCE Year 11 Biology Flashcard Review
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Where is DNA found in a prokaryotic cell?
In the nucleoid region of the cytoplasm (circular chromosome), plus plasmids.
Function of rough ER?
Ribosome-studded membranes that fold and transport proteins for export or membranes.
Function of smooth ER?
Synthesis of lipids and steroids; detoxification.
Function of the Golgi apparatus?
Modifies, sorts and packages proteins into vesicles.
Function of lysosomes?
Contain digestive enzymes that break down worn-out organelles and engulfed particles.
Totipotent vs pluripotent?
Totipotent forms all cells including placenta; pluripotent forms all body cells but not placenta.
Example of a multipotent stem cell
Haematopoietic (bone marrow) stem cell – makes all blood cell types.
Hierarchy of organisation
Cell → tissue → organ → system → organism.
Role of cholesterol in the membrane
Regulates fluidity and stabilises the bilayer.
Role of glycoproteins
Cell recognition, signalling and adhesion.
Endocytosis vs exocytosis
Endocytosis takes material in by forming vesicles; exocytosis releases material by vesicles fusing with the membrane.
Why does SA:V limit cell size?
Volume grows faster than surface area, so the membrane cannot exchange materials fast enough for a large cell.
Monomer of starch and glycogen?
α-glucose.
What bond joins amino acids?
Peptide bond, formed by condensation.
Products of lipase action on a triglyceride?
Fatty acids and monoglycerides (ultimately glycerol).
Where are amylase enzymes produced?
Salivary glands and pancreas.
Why does pepsin work in the stomach but not the small intestine?
Its optimum pH is about 2; the alkaline intestine changes R-group charges and its active site.
Define activation energy.
The minimum energy needed to start a reaction; enzymes lower it.
Lock-and-key vs induced fit?
Lock-and-key: rigid complementary site. Induced fit: active site moulds around substrate, straining bonds.
Why does rate plateau at high substrate concentration?
All active sites are occupied (saturated); enzyme concentration is limiting.