unit 1

Question 1

what are lysosomes?

Answer 1

Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria.

Question 2

how is action potential generated?

Answer 2

Voltage begins to rise from -60mv. Gates in voltage-gated channels open. Influx of Na+ ions into axon membrane. This is depolarization. This causes action potential in that section of the neurone. Sets off depolarisation in next section of neurone. Approx +30mv when the Na+ channels close. Gates in K+ gated channels open. K+ ions flow into membrane (slower that Na+ influx). Potential difference returns to -60mv. This is repolarisation.

Question 3

what are the three types of epithelial tissue?

Answer 3

Columnar, Squamous, Endothelium