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1.3.7Unit 1: Lifestyle, Transport, Genes and Health

Data on Cholesterol and Lipoproteins — IAL Edexcel Linear Revision Notes & Topical Questions

5 min read 5 parts Lesson 25 of 29 Unit quiz

📚 IAL Edexcel Linear Hub / Topical Revision
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Curriculum Equation Key معادلة تفاعل تكوين الإستر (الأسترة) - Esterification Reaction EquationFast Exam Solution
R-COOH + R2-OH ⇌ (conc. H₂SO₄) R-COO-R2 + H₂O
Word Equation & Conditions: حمض كربوكسيلي + كحول (في وجود حمض الكبريتيك المركز كعامل حفاز ونازع للماء) ⇌ إستر + ماء
Location & Specifications: الكيمياء العضوية للثانوية العامة والتحصيلي و Edexcel Chemistry.
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Part 1 of 5Cholesterol and Lipoproteins

Cholesterol
  • Cholesterol A lipid made in the liver and taken in the diet, needed for cell membranes, steroid hormones and bile salts.
Lipoproteins
  • Lipoproteins Cholesterol is carried in the blood by lipoproteins, which are particles made of lipids and protein.
LDL
  • LDL Low-density lipoproteins carry cholesterol from the liver to body tissues and high levels can lead to deposits in artery walls.
HDL
  • HDL High-density lipoproteins carry cholesterol from tissues back to the liver for recycling or excretion, lowering blood cholesterol.

Part 2 of 5Link to Heart Disease

Link to Heart Disease
Bad and good
  • Bad and good LDL is often called bad cholesterol and HDL good cholesterol because of their effects on atheroma formation.
Balance
  • Balance The ratio of LDL to HDL is more informative than the total cholesterol concentration alone.
Saturated fat
  • Saturated fat A diet high in saturated fat tends to raise LDL, while unsaturated fats can help to lower it.
Inheritance
  • Inheritance Some people inherit a condition that gives very high LDL levels, so they are at risk even with a healthy diet.

Part 3 of 5Analysing the Data

1
Identify the variables, such as blood cholesterol or the LDL to HDL ratio, and the outcome, such as the number of heart attacks.
2
Describe the trend, quoting figures, for example how the rate of CVD changes as LDL concentration rises.
3
Consider whether a correlation shown can be explained by other factors such as smoking, age or diet.
4
Use calculations such as ratios, percentage change and relative risk to compare groups.
5
Make a conclusion limited to the data, and suggest further evidence, such as a larger or longer study.

Part 4 of 5Worked Example

Question

  • A patient has an LDL concentration of 3.6 mmol per dm³ and an HDL concentration of 1.2 mmol per dm³.
  • Calculate the LDL to HDL ratio.

  1. Ratio = LDL ÷ HDL.
  2. Ratio = 3.6 ÷ 1.2 = 3.
  3. Written in the form LDLHDL this is 3 : 1.

Answer The LDL to HDL ratio is 3 : 1.

Part 5 of 5Exam Checklist & Tips

1.3.7 – Key Points for the Exam

  • Cholesterol A lipid used in membranes and in making steroid hormones.
  • LDL A lipoprotein that carries cholesterol from the liver to the tissues.
  • HDL A lipoprotein that returns cholesterol from tissues to the liver.
  • Lipoprotein A particle of lipid and protein that carries lipids in the blood.

Common Mistakes

  • Mixing up the roles of HDL and LDL.
  • Stating that all cholesterol is harmful; the body needs it.
  • Using total cholesterol alone without considering the LDL to HDL balance.
  • Treating a correlation between cholesterol and CVD as proof of cause.

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