Nutrition types and Nutrient Compounds

Nutrition types and Nutrient Compounds

By the end of this chapter, you will be able to:

(a) understand the term nutrition.

(b) identify the food nutrients, their sources, and importance to humans.

(c) perform food tests for various nutrients.

(d) appreciate the importance of a diet containing the different nutrients.

(e) appreciate the concept of balanced diet in relation to age, sex, and an individual’s activity.

(f) appreciate the causes and effects of nutrient deficiency in humans including diseases related to malnutrition.

(g) calculate body mass index (BMI)and explain its implication.

(h) identify the major plant mineral nutrients (N, P, K, Mg, Ca, S) their role and the symptoms of deficiencies.

Introduction

In this Chapter, you are going to build on the fact that all living organisms need nutrients to support their metabolism and growth.

Also that most of these nutrients have to be obtained from their environment. You will be able to understand the meaning of nutrition, food nutrients, their sources and importance to humans and effects of nutrient deficiency in humans.

Look at the different nutrient requirements of organisms and of humans depending on age, state of health, level of activity, and other features.

You will also identify the different food nutrients in food using specific chemical tests. You will also identify the major plant nutrients, their role and symptoms of deficiency.

3.1 Nutrition

All living organisms are made up of a large number of chemical substances. Most of these substances are built up in the organism using the food which has been taken in, digested and absorbed.

These chemical substances found in organisms are used in different ways. In this activity, you are going to discuss the meaning of nutrition.

Figure 3.1 A chart showing the types and serving sizes for the foods on should eat everyday to stay healthy

Activity Finding out the meaning of the term nutrition,

Key question

What is nutrition?

What you need

Biology textbooks

Notebooks

What to do

In pairs, discuss and research on the meaning of the term nutrition.

Share and agree on the meaning with the class.

3.2 Food nutrients, their sources and importance

The body needs a variety of food nutrients for normal functioning and growth. These are of different categories depending on their importance.

For instance, proteins which have body building nutrients, carbohydrates which are energy giving vitamins and mineral salts that are body protecting.

These are obtained from the foods we eat in form of plant and animal matter.

Activity 3.2 Researching on different food nutrients, their sources and importance to humans

Key question

What are the different food nutrients required by the body?

What you need

Biology textbooks

Computer connected to the internet

What to do

1 In groups of 3 or 4, discuss and research on the different food nutrients required by the body, their sources and importance.

2 Record your findings in a suitable table.

3 Display and compare your findings with the whole class

3.3 Vitamins and minerals

In addition to the nutrients identified in Activity 3.2, the body requires a variety of other nutrients in smaller quantities to function efficiently.

These are mineral salts and vitamins. Deficiency of any of these even if the body is supplied with enough of the other nutrients often results in deficiency diseases.

Activity 3.3 Researching on vitamins, their sources, functions and effects of deficiency

Key questions

What are the different types of vitamins, their sources, functions?

What are the effects of their deficiencies?

What you need

Computer with internet/Biology textbooks

Notebooks

Pens/pencils

Rulers

What to do

1 In groups, research on the different types of vitamins the different vitamins, their sources, functions and effects sources, functions and effects of deficiency. What are th deficiency?

2 Record your findings in your notebooks.

3 Make a suitable report and present it to the rest of the class

Activity 3.4 Researching on minerals, their sources, functions and effects of deficiency

Key questions

What are the different mineral elements needed in the human body?

What are different sources, functions and effects of different minerals on the human body?

What you need

Pens/pencils

Notebooks

Rulers

What to do

1 In groups of 3 or 5 research on the different mineral elements sources, functions and effect of their deficiencies.

2 What are the different mineral elements, sources, and thei functions?

3 Discuss them among your group members and record them in your notebooks. the class.

4 Choose a suitable method and make a report to the rest of the class

3.4Food tests

Carbohydrates such as starch, reducing sugar and n in food by specific chemical tests. These tests differ in reducing sugar can be detected in food by simple chemi tests.

Vitamins, proteins and lipids can also be identify types of reagents used, procedure and observed results

In this section you are going to carry out some experimental procedures to, identify common nutrients in food. In these tests you will use a test solution which changes colour.

These change colour to specific colours which indicates presence of certain nutrients. Carefully observe the colour of the test solution and the change in colour of the food.

A colour chart has been provided. In the next Activity 3.5, you are going to carry out tests on different foods.

Activity 3.5 Carrying out tests on different foods,

Key question

What are the tests used to identify food substances?

What you need

Test tubes, test tube holder

Mortar and pestle Beakers

Distilled water/de ionised water

Colour chart

Droppers

Plain papers

Food types such as: potatoes, egg yolk, milk, groundnuts and pineapple.

Food test reagents: lodine solution, Benedict’s solution, copper Il sulphate solution, sodium hydroxide solution, DCPIP solution (dichlorophenol indophenol), ethanol, and source of heat.

What to do

Carry out tests on the foods provided

Record your observation and conclusions

3.5 Balanced diet and effects of imbalanced diet

For proper growth, ones body requires all the food nutrients in their correct proportions.

However this varies with ones age, gender, state of health and activity. In this activity you are to discuss and research on balanced diet and effects of imbalanced diet

Activity 3.6 Discussing what constitutes a balanced diet

Key question

What is a balanced diet?

What you need

Notebooks

Textbooks

Computer with internet

What to do

1 In groups discuss, research and report on;

a) The meaning of the term balanced diet and how a balanced diet varies with age, sex, and activity for example, for a baby, child, adult woman, adult man, an athlete and an inactive person.

b) The likely effects of an imbalanced diet.

2 Record your finding.

3 Present your findings to the whole class.

3.6 Malnutrition

Some causes of malnutrition in the community include:

Insufficient supply of right food .

Uneven geographical distribution of food

Seasonal lack of food e.g. dry season

Ignorance of the basic principles of good nutrition

Local customs which discourage the eating of certain eating foods taboos on women eating eggs, certain tribes not eating fish

Malnutrition occurs when the body lacks particular nutrients in the diet for a long period of time. It is often detected by one developing symptoms indicating that something is lacking in one’s diet.

Sometimes eating disorders like overfeeding on particular foods, feeding on junk food (such as chips and liver can result in malnutrition expressed in form of obesity, bulimia or anorexia.

Some people use drugs such as diet pills for thinning (sliming) or to change body image or fattening which can also lead to eating disorders

Activity 3.7 Discussing what constitutes malnutrition

Key question

What are the effects of malnutrition on one’s body?

What you need

Biology textbooks

Notebooks

Computers with internet

What to do

In your group discuss, research and report on the dangers of:

1) Obesity, bulimia and anorexia

2) Use of drugs (diet pills and steroids) to change body image.

3.7 Body mass index (BMI)

Figure 3.6 Materials used to measure BMI

People have different body weight and some others are said to be thin. Being thin or fat in itself may not be an indication of poor nutrition or health.

However there is what is medically known as a healthy weight. To determine this healthy weight, it is recommended that one knows his/he body mass index in relation to the standard BMI.

The body mass index is a measure of the ratio of the bod weight in kilograms to the square of the body’s height n meters.

The body mass index is the weight for height standard that is most closely related to body fat content. In this activity you are going to determine the ratio of one’s body mass to one’s height.

This is a useful method of finding out if one is overweight or underweight.

A useful formula to use is BMI = Body weight (Kg)/Height (m)2

Activity 3.8 Determining body mass index (BMI)

Key question

What is body mass index?

What you need

Tape measure

Ruler

Weighing scale

BMI chart

What to do

1 In your group, measure each one’s weight (kg) and height (m) and use the results to calculate the body mass index.

2 Refer to the standard BMI chart to determine each one’s BMI status.

3 Discuss the implication of being underweight and overweight and what to do in both cases.

Standard BMI Chart

3.8 Self esteem in relation to body size

Activity 3,9 Finding out self-esteem in relation to physical differences in body shape and size

Key question

How does body shape and size affect self-esteem?

What you need

Notebooks, manila, markers

Medical workers

What to do

1 In your group listen to the medical worker talking about self- esteem in relation to physical differences in body size and shape.

2 Prepare and write a brief report on self-esteem in relation to physical differences in body shape and size.

Activity 3.10 Discussing self esteem

Key question

What is self esteem and how can you promote it?

What you need

Computer connected to internet.

Book on self image/chart showing self image.

Notebooks/writing pads.

Pens.

What to do

1 In groups of 5, brainstorm on the term self esteem.

2 Research using internet/books on self image e.g. Josh McDowell, His image my image.

3 Discuss the emotional pillars that support self-worth i.e.

a) need to belong, be loved and know we are special.

b) need to feel accepted and worthwhile.

c)need to feel adequate and competent.

4 Prepare a role play of an awkward insecure teenager with a low self esteem.

5 Present your play to the rest of the class.

3.9 Plant mineral nutrition

Figure 3.9 Aspects of plant nutrition

Plants require some mineral nutrients for their growth. They obtain them from the soil using their root system. However Plants require some mineral nutrients for their growth.

They Such plants show signs of deficiency which can be linked some soils lack some minerals which affect their to the particular nutrient that is deficient.

In this activity you will grow plants in a series of solutions This is called water culture. One of the solution contains all the chemical elements that are needed for plant growth This serves as a control.

For the other solutions each c lacks a particular element.

Activity 3.11 Investigating the need for all plant mineral nutrients for proper plant growth

Key question

What nutrients affect plant growth?

What you need

8 bottles of the same size

Bean or maize seedlings

Water

Black papers

Markers

What to do

1 Obtain eight bottles and label them A to H

2 Fill each bottle with the following solutions

A-Complete solution containing all necessary elements

B- Complete solution minus nitrogen

C-Complete solution minus phosphorous

D-Complete solution minus sulphur

E-Complete solution minus magnesium

F-Complete solution minus potassium

G-Complete solution minus calcium

H-Complete solution minus iron

3 Obtain eight identical seedlings of maize or beans.

4 Put one seedling in each bottle as shown above.

5 Wrap a sheet of black paper round each bottle to shield it from light. This will prevent algae growing inside.

6 Put the bottles in a warm, light place such as close to a window.

7 Observe the seedlings at intervals over the next two to three weeks.

8 Present your findings to the rest of the class.

Use of mineral nutrients in plants and their deficiencies

Each of the mineral nutrients required for normal plant growth has a particular function which contributes to the overall growth of the plant.

This is why deficiency of a particular mineral nutrient leads to improper growth of the plant. This is evident by specific signs that appear on the plant especially on the leaves. In the next Activity 3.12, you are to research on the uses of mineral elements to plant growth and effects of their deficiency.

Activity 3.12 Finding out the use of mineral nutrients to plants and their deficiencies

Key questions

What are the uses of mineral nutrients to plants and what effects do their deficiencies cause?

What you need

Biology textbooks

Notebooks

Computer with internet

What to do

1 In your groups, research on the uses of nitrogen, potassium, phosphorous, magnesium, calcium and sulphur to plants and effect of their deficiencies.

2 Present your findings to the class in form of a table (illustrate in poor health showing deficiency of particular nutrients. if possible) by examples of leaves in good health, and those in poor health showing deficiency of particular nutrients

Chapter summary

 In this chapter, you have learnt that:

• Nutrition is the process of obtaining nutrients.
• Nutrients are chemical substances found in food which are used in the human body for growth, body building and defense against diseases
• Food contains different nutrients like proteins, carbohydrates, lipids, vitamins and minerals each with its own importance to one’s life. Food tests reveal the identity of nutrients in food.
• A balanced diet is necessary for one’s healthy living and differs with age, sex and activity.
• Imbalanced diet and malnutrition has effects on one’s health. Obesity, bulimia and anorexia are indicators of imbalanced diet.
• Body Mass Index (BMI) can be useful to establish whether one is overweight or underweight.
• Physical differences in body shape and size can affect one’s self esteem.
• Plant growth requires several minerals whose deficiency affects growth.

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