Topic 13

Question 1

Excretion: excretory products

Answer 1

Important to excrete as build up of these substances would reach toxic level and destroy tissues
. Excreted in lungs: carbon dioxide
. Excreted in kidneys: excess waters, excess ions, urea

Question 2

Excretion in the liver: Deamination

Answer 2

Removal of nitrogen-containing part in excess amino acids (ones that aren’t needed to make protein) to make urea in the liver

Question 3

Excretion in the liver: Assimilation

Answer 3

Absorbed food molecules become part of cells or used by cells (eg amino acids into proteins like enzymes)

Question 4

The kidneys: blood in kidneys

Answer 4

Filtered in kidney nephrons -> located across kidney cortex and medulla

Question 5

The kidneys: filtration

Answer 5

1. Blood from renal artery flows through the glomerulus (bundle of capillaries -> membranes keep big molecules in blood stream)
2. High pressure squeezes water, urea, ions and glucose out of blood into capsule

Question 6

The kidneys: reabsorption

Answer 6

1. All glucose reabsorbed by active transport
2. Some ions reabsorbed -> excess ions aren’t
3. Most water reabsorbed by osmosis -> urea more concentrated

Question 7

The kidneys: releases of waste

Answer 7

1. Formation of urine: urea, excess ions and excess waters
2. Urine continues out of nephron through ureter into bladder -> stored before released through urethra