Unit notes and practice questions
Everything here is for unit 5 of the Grade 9 Biology textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.
The cards filed under this chapter on the Grade 9 Biology page. Open one at a time.
When you use it
Use this to calculate a person's body mass index and classify their weight category from their body mass and height.
Watch out
Height must be converted to metres before squaring, not left in centimetres. Athletes with high muscle mass can register a high BMI without excess body fat.
Drafted from Grade 9 Biology, pages 103-136, then checked twice before it went up
| Condition | Diagnostic Definition | Underlying Cause |
|---|---|---|
| Wasting | Low weight-for-height | Recent and severe food shortage or illness |
| Stunting | Low height-for-age | Chronic or recurrent undernutrition |
| Underweight | Low weight-for-age | Combined acute and chronic nutritional deficit |
When you use it
Use this to distinguish between the anthropometric measures used to diagnose child undernutrition.
Watch out
Wasting compares weight against height (acute), whereas Stunting compares height against age (chronic).
Drafted from Grade 9 Biology, pages 103-136, then checked twice before it went up
| Nutrient | Rich Food Sources | Main Role | Deficiency Disease |
|---|---|---|---|
| Protein | Meat, fish, eggs, soya, milk | Growth and tissue repair | Kwashiorkor |
| Carbohydrate | Potato, wheat, maize, rice, bread | Primary source of energy | Marasmus |
| Vitamin C | Oranges, lemons, citrus fruits | Tissue repair and wound healing | Scurvy |
| Vitamin D | Fish oil, milk, butter, sunlight | Absorption of calcium and bone formation | Rickets |
| Iron | Liver, red meat, eggs, Tikur teff | Hemoglobin synthesis in red blood cells | Anemia |
| Calcium | Milk, cheese, green vegetables | Bone, tooth structure and muscle contraction | Rickets and weak bones |
When you use it
Use this table to match dietary nutrients with their essential biological functions and specific deficiency disorders.
Watch out
Do not confuse Kwashiorkor (protein deficiency, causes abdominal and leg swelling) with Marasmus (energy and carbohydrate deficiency, causes extreme wasting and an old-looking face).
Drafted from Grade 9 Biology, pages 103-136, then checked twice before it went up
10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.
Question 1
On average, how much energy is provided by one gram of carbohydrate?
Answer: A 16 kJ
Why
According to the textbook, one gram of carbohydrate provides an average of 16 kJ of energy, while one gram of protein provides 17 kJ and one gram of lipid provides 37 kJ.
Question 2
Which deficiency disease is caused by a lack of vitamin C (ascorbic acid) in the diet?
Answer: B Scurvy
Why
A deficiency in vitamin C causes scurvy, which leads to bleeding gums, poor wound healing, and bleeding under the skin.
Question 3
According to the textbook, a person with a Body Mass Index (BMI) of 30.0 or above is classified as:
Answer: D Obese
Why
A BMI below 18.5 is underweight, 18.5 to 24.9 is normal weight, 25.0 to 29.9 is overweight, and 30.0 and above is categorized as obese.
Question 4
What term is used for a disease that occurs permanently in a specific place or population, such as malaria in the Afar region?
Answer: A Endemic
Why
An endemic disease is one where the disease-causing agent exists permanently in a specific place or population.
Question 5
Iron is an essential mineral needed to synthesize hemoglobin. Which local food is specifically mentioned in the textbook as a rich source of iron?
Answer: A Tikur teff
Why
The textbook lists red meat, liver, kidney, eggs, groundnuts, and Tikur teff as important dietary sources of iron.
Question 6
Which combination of simple sugars forms the disaccharide maltose?
Answer: A Glucose + Glucose
Why
Maltose is formed by Glucose + Glucose. Glucose + Fructose forms sucrose, and Glucose + Galactose forms lactose.
Question 7
Which condition of undernutrition is defined as low height-for-age due to chronic undernutrition?
Answer: B Stunting
Why
Stunting is defined as low height-for-age resulting from chronic undernutrition, while wasting is low weight-for-height.
Question 8
What harmful effect does carbon monoxide from cigarette smoke have on the human circulatory system?
Answer: A It combines permanently with hemoglobin, reducing oxygen transport
Why
Carbon monoxide diffuses into red blood cells and combines permanently with hemoglobin to form carboxy-hemoglobin, preventing it from carrying oxygen.
Question 9
Almaz has a body mass of 80 kg and is 2.0 metres tall. What is her Body Mass Index (BMI), and what is her weight status?
Answer: A 20.0, normal weight
Why
BMI is calculated as body mass (kg) / height2 (m2). Here, 80 / (2.0)2 = 80 / 4 = 20.0. A BMI of 20.0 falls in the range of 18.5 to 24.9, which is normal weight.
Question 10
Which active chemical compound is present in fresh khat leaves and affects the central nervous system?
Answer: A Cathinone
Why
Khat contains cathinone, a stimulant chemical found in fresh leaves that degrades as the plant dries.
The app holds 12 questions on this unit, marked as you go. These are the first 10.
Unit 5 runs from page 103 to page 136 of the Ministry of Education edition.
Ministry of Education edition, English, 165 pages
Temari turns this chapter into timed practice and marks it as you go, with an AI tutor to explain anything that did not land.
Start free
Temari.et is also an Android app, free on Google Play.
