13. (a) (i) Explain what is meant by the term homeostasis - Leaving Cert Biology - Question 13 - 2020
Question 13
13. (a) (i) Explain what is meant by the term homeostasis.
(ii) Give one reason why homeostasis is important in organisms.
(iii) Explain what is meant by the term ex... show full transcript
Worked Solution & Example Answer:13. (a) (i) Explain what is meant by the term homeostasis - Leaving Cert Biology - Question 13 - 2020
Step 1
Explain what is meant by the term homeostasis.
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Answer
Homeostasis refers to the ability of an organism to maintain a stable internal environment despite external changes. This involves regulating various physiological processes such as temperature, pH, and electrolyte balance, ensuring optimal functioning of cells and systems.
Step 2
Give one reason why homeostasis is important in organisms.
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Answer
Homeostasis is crucial for metabolic processes to occur efficiently. For instance, maintaining a stable temperature is vital for enzyme activity and overall cellular metabolism.
Step 3
Explain what is meant by the term excretion.
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Answer
Excretion is the process of removing waste products and toxins from the body, such as urea and carbon dioxide, which are the byproducts of metabolism. This is essential for maintaining internal balance and health.
Step 4
State the precise location in the body where urea is made.
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Answer
Urea is made in the liver.
Step 5
Name the food biomolecule from which urea is derived.
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Answer
Urea is derived from proteins, specifically from the breakdown of amino acids.
Step 6
In which part of the kidney is the Bowman’s capsule located?
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The Bowman’s capsule is located in the cortex of the kidney.
Step 7
In which part of the kidney is the Loop of Henle located?
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Answer
The Loop of Henle is located in the medulla of the kidney.
Step 8
Name the part labelled ‘A’.
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Answer
The part labelled 'A' is the ureter.
Step 9
Draw a large diagram of a nephron and its associated blood supply from a human kidney.
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Answer
To effectively illustrate a nephron, ensure to include parts such as the Bowman’s capsule, Loop of Henle, Proximal convoluted tubule, Collecting duct, Distal convoluted tubule, and Glomerulus. Make sure all components are correctly labelled to show the relationship of the nephron to its blood supply.
Step 10
Using the data from the table above, what is the main difference between plasma and filtrate?
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Answer
The principal difference is that blood plasma contains proteins (7 g/100 cm³), while glomerular filtrate contains none. This is because proteins are too large to pass through the glomerular membrane.
Step 11
Explain the results between:
1. Blood plasma and glomerular filtrate.
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Blood plasma includes glucose molecules that are small enough to pass through the glomerulus, whereas glomerular filtrate shows a similar glucose level. Thus, glucose is effectively filtered from blood plasma to filtrate.
Step 12
Explain the results between:
2. Glomerular filtrate and urine.
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Answer
Glomerular filtrate retains glucose, but urine shows a significantly reduced level (0.1 g/100 cm³). This indicates that glucose is mostly reabsorbed back into the bloodstream after filtration.
Step 13
What is the effect on the volume of urine produced by a high salt intake?
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Answer
A high salt intake leads to decreased urine volume because the body retains water to balance the increased sodium concentration.
Step 14
Explain your answer to part 1.
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Answer
High salt intake triggers the release of ADH (antidiuretic hormone) from the pituitary gland, which increases the permeability of the collecting ducts to water, resulting in more water being reabsorbed back into the bloodstream and consequently reducing urine output.
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