Daily energy requirement simply means the energy required per day for activities. Typically, it can be calculated using your basal metabolism rate (BMR), which is the least amount of energy required to ensure that your body organs are functioning well and also to maintain your body temperature around 36.9 degree Celcius. The daily energy requirement is dependent on many factors which is stated in this Part 3 of Berry Berry Easy SPM Biology Form 4 notes on Nutrition. In this post, Berry Readers will also be exposed to the concept of food energy content.
[Tips: Students often make the mistake of confusing calories and joules. Most of the time it is due not converting the units when solving calculation-based questions. Sometimes it is the use of multiplication instead of division, and vice versa during the conversion. Just remember that a calorie is 4.2 joules, so to convert calorie to joule, you'll multiply 4.2. To convert joule to calorie, you divide by a factor of 4.2. So make sure that you do all the necessary conversions of calories to joules in a correct manner.]
SPM Biology Form 4 Notes – Nutrition (Part III)
Factors Affecting Daily Energy Requirement
Balance diet is essential for healthy growth and development of the body.
- Age – children and teenagers need more energy due to their high metabolic rate.
- Sex – male adult needs more energy due to in males have high metabolic rate.
- Pregnancy and lactation – pregnant women need more energy due to support the growing foetuses and produce milk for their babies.
- Occupation – an active person requires high energy due to the person does a lot of heavy work.
- Size or body weight – a person smaller in size has a larger surface area per unit volume. Thus, the rate of heat loss is high.
- Climate – people living in cold countries need more energy to maintain body temperature.
- Genetics – genetics disposition in certain person may decide different metabolic rate.
- Health – In sufficient secretion of thyroxine hormone may cause lower in metabolic rate.
- Lifestyle – An active person requires higher energy than a passive person
Energy Content of Food
- Bomb calorimeter – used to calculate the energy value of various types of food samples.
- One calorie (cal) = 4.2 joules (J)
- Energy value of food (kJ g-1) = (4.2 x mass of water x increase in temperature) / (mass of food sample x 1000), specific heat capacity of water, C = 4.2 J g-1 ˚C-1; mass of water in g; temperature in ˚C and mass of food sample in g.
This represents the end of the Part 3 of the short notes on the topic of Nutrition for SPM Form 4 Biology students by Berry Berry Easy. In the next post in this series of summarised notes, you’ll learn about the classes of food nutrient. So do check back.