Excretion as an Example of Homeostatic Control | OCR A-Level Biology A (H420)
Excretion as an Example of Homeostatic Control
- 110 questions
- 9 subtopics
- Module 5: Communication, homeostasis and energy
- Component 01 and Component 03
Excretion as an example of homeostatic control is the second section of Module 5.
It covers why nitrogenous waste must become urea, the structure of the liver, the nephron and the stages of filtration and reabsorption, how ADH controls water balance, kidney failure and its treatments, and what a urine test can detect.
Sample questions from Excretion as an Example of Homeostatic Control
Answer each one closed book first, then open the answer.
-
Excretion and nitrogenous waste
Why must carbon dioxide be excreted from the body?
Show the answer
Carbon dioxide combines with water to form carbonic acid, which lowers blood pH. -
The liver: structure and function
What are hepatocytes and how are they arranged within a lobule?
Show the answer
Hepatocytes are the main liver cells, arranged in rows radiating out from the central vein. -
The structure of the kidney
What is the function of the ureter?
Show the answer
The ureter carries urine from the kidney to the bladder. -
The nephron
Which part of the nephron is the main site of selective reabsorption?
Show the answer
The proximal convoluted tubule. -
Ultrafiltration
What is the role of the capillary endothelium in the filtration barrier?
Show the answer
The capillary endothelium has pores that allow small molecules to pass through. -
Selective reabsorption and the loop of Henle
By what process is water reabsorbed in the proximal convoluted tubule?
Show the answer
Water is reabsorbed by osmosis following the reabsorption of solutes. -
Osmoregulation and ADH
How does ADH reach its target tissue?
Show the answer
ADH travels in the blood to the collecting ducts of the kidneys. -
Kidney failure, dialysis and transplant
Why does kidney failure cause fluid retention and oedema?
Show the answer
Due to the inability to regulate water balance.
The 9 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Excretion and nitrogenous waste | What excretion is and why it matters for homeostasis, and how ammonia produced by deamination is converted to urea before it leaves the body. | 9 |
| The liver: structure and function | The hepatic artery, hepatic portal vein and bile duct, lobules, hepatocytes, sinusoids and Kupffer cells, and the storage, detoxification and urea formation the liver carries out. | 18 |
| The structure of the kidney | The cortex, medulla and renal pelvis, the vessels supplying and draining the kidney, the ureter, and the parts of a nephron named in the order filtrate passes through them. | 11 |
| The nephron | Bowman's capsule and the glomerulus, the afferent and efferent arterioles, and what the proximal convoluted tubule, loop of Henle, distal tubule and collecting duct each do. | 17 |
| Ultrafiltration | What is forced through the filtration barrier and what is held back, and the roles of the capillary endothelium, the basement membrane and the podocytes. | 8 |
| Selective reabsorption and the loop of Henle | How glucose, amino acids, sodium and water are reabsorbed and the adaptations of the tubule cells, and the countercurrent multiplier that concentrates the medulla. | 13 |
| Osmoregulation and ADH | Osmoreceptors in the hypothalamus, where ADH is made and released, the aquaporins it places in the collecting duct, and the feedback loop that results. | 9 |
| Kidney failure, dialysis and transplant | Glomerular filtration rate and what failure does to urea, electrolytes and fluid balance, and how haemodialysis and transplant compare. | 15 |
| Urine testing and monoclonal antibodies | Why urine is useful in diagnosis, how a pregnancy test uses monoclonal antibodies to detect hCG, and the detection of anabolic steroids and other drugs. | 10 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
-
Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
-
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
-
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby sections
OCR A-Level Biology A Active Recall Guide
Every section, not just this one. 1,833 questions with their answers.