IB myp 4-5 Biology – Practice Questions- All Topics
Topic :Metabolism-Nutrition
Topic :Metabolism– Weightage : 21 %
All Questions for Topic : Nutrition,Digestion,Biochemistry and enzymes,Movement and transport,Diffusion,Osmosis,Gas exchange,Circulation,Transpiration and Translocation,Homeostasis
Nutrients are substances that provide you energy. Nutrition supplies living organisms with the molecules that they need to keep them alive.
As we have heterotrophic nutrition, we are constantly taking in organic and inorganic molecules from our surrounding environment that our systems transform in order to obtain the needed energy to drive life processes and the raw material for the growth and repair of tissues. These organic and inorganic molecules that our cells need are referred to as nutrients
Feeding is the process by which those nutrients are obtained from the environment, while nutrition includes a number of processes that allow organisms to transform those nutrients so our cells can use them.
Our health depends on our diet, or the kind of food that we eat. Not including the necessary nutrients and in the correct proportion, may result in malnutrition, which could lead to malfunctioning of the body and often times to illness.
A poor diet can lead to some non-infectious diseases such as endocrine and metabolic diseases or deficiency diseases. Obesity and diabetes as examples of endocrine and metabolic diseases, and look into anaemia as a deficiency disease. However, there are many other diseases directly related to a poor diet so it is very important that you understand what a balanced diet is and how to develop healthy eating habits.
There are also psychological diseases that are not directly related to a poor diet, but would lead to eating disorders and therefore later complications such as anorexia and bulimia.
A balanced diet provides all the nutrients in the correct amounts needed to carry out the life processes. The Mediterranean diet is a very good example of a balanced diet, as we will see in more detail.
In a balanced diet, one needs BALANCE, VARIE’TY and MODERATION.
Categories of food
Macronutrients (high quantities)
- Carbohydrates
- Proteins
- Fibers
- water
- Fats
Micro nutrients (small quantities)
- Vitamins
- Minerals
Water is a Universal Solvent. It carries Nutrients and Waste Regulates body Temperature, Dissolves Nutrients and Lubricates joints. Up to $70 \%$ of the human body is water.
Fiber is not really a nutrient. It just helps in digestion (which is why faeces is often the quick result of consuming an apple). Fiber reduces the chance of obesity, and is not broken down during digestion.
Carbohydrates: there are two types: monosaccharides and polysaccharides. Their main function is to provide our cells with energy.
*Monosaccharides are the simplest carbohydrates, for example glucose, and fructose, found in honey and fruits. They are soluble in water, so they are easily transported in blood and dissolve in the cytoplasm of the cell. Glucose is oxidised (used) in cellular respiration to release energy for different processes such as active transport, cell division, muscle contraction etc. It is therefore the main source of energy for our cells.
*Polysaccharides: Complex molecules formed by joining several monosaccharides together. They must be split into simple monosaccharides in order to be used by our cells. They are water insoluble so they are good stores of energy. The most important one involved in human nutrition is starch, which is made by joining many thousands of glucose molecules together. Cellulose, contained in vegetable fibre, also belongs to this group, and even though we cannot use it as a source of energy plays an important role in our diets, as we will see later.
Excess carbohydrates can be stored as glycogen and fats.
- Polysaccharides have vitamins, minerals and fiber.
- Proteins, or Polypeptides, provide energy on the last resort. They help repair body His sues. They are made up of ch epical compounds called amino acids. There are 20 types of amino acids (building blocks of proteins) 11 of these can be produced by the human body a of these come from the food we consume. Complete proteins provide these a essential nutrients.
- Fats/Lipids have the most amount of storage. They are hydrocarbons. Its functions are:
- Providing substances
- Providing energy
- Enhancing taste/texture of food.
Lipids: Lipids, also known as fats are an important source of energy. They are particularly valuable as energy storage because they are insoluble in water. They are stored in the cells of adipose tissue. Lipids are formed by joining three molecules of fatty acids to one molecule of glycerol. There are two types of lipids: fats, which are solid at room temperature and oils, which are liquid at room temperature. Lipids are a main component of cell membranes, forming barriers between watery environments, such as the cell and its surrounding. They also provide insulation (electrical insulation around nerve cells, and thermal insulation beneath the skin). Steroids hormones, including sex hormones are made from cholesterol. The most familiar/known lipids are triglycerides and cholesterol.
Cholesterol is a fat-like substance part of every cell of the body. It helps the body make necessary cells and aids in digestion. It is found in animal meat and created in the human body
Proteins: These nutrients are the most important macromolecules. Around 50% of the dry cell mass in our body are proteins. Proteins carry out many different functions such as:
- structural materials – muscles, tendons, bones, nails and hair
- transport molecules, such as haemoglobin in blood,
- hormones, such as insulin,
- natural catalyst, as all enzymes are proteins,
- in defence against diseases (antibodies).
Important Note: (enzymes regulate all the metabolic reactions in our body)
Proteins are made of long chains of subunits called amino acids joined together. There are 20 different amino acids. All proteins are made from the same 20 amino acids that are joined in a vast number of different orders. Out of these 20 amino acids, 12 can be produced by our body, however, there are 8 amino acids we cannot produce and must be provided by our diet. We refer to those as the essential amino acids. Amino acids are soluble so they are easily transported in living organisms.
Vitamins and mineral: Substances essential for the body as they regulate metabolic reactions as well as allow our bodies to use other nutrients efficiently. Some minerals make up the structure of our body, for example calcium is an important constituent in bones and teeth. Some other minerals are used to regulate the nervous system, such as sodium and potassium. And Iron takes part in oxygen transport. Vitamin D is needed for the absorption of calcium. And vitamin C aids with the absorption of iron.
Vitamins and mineral are only needed in very small amounts, but lacking the necessary vitamins can cause a variety of problems and illnesses.
Vitamins are nutrients that do not provide energy. They help regulate chemical processes.
Minerals are inorganic micro-nutrient’s that do not provide energy
Two types Of Vitamins:
(1) Water Soluble C, B (large quantities)
(2) Fat Soluble $A D, E, K$ (small quantities)
Vitamin A (Fat Soluble):
- Sources: Green vegetables, liver
- Deficient: Nyctalopia
- Function 1: Keeps skin thar healthy
- Function 2: Aids in night vision
vitamin B-Complex (water Soluble):
- Sources: Peas, wheat
- Deficiency -Vitamin B-12 Deficiency
- Function 1:Utilises body energy
- Function 2: Helps brain / nerves be strong
vitamin C (water Soluble):
- Sources: Citrus fruits, Kiwi
- Deficiency: Scurvy
- Function 1. Heal Wounds
- Function 2: Fight Infections
vitamin D (Fat Soluble):
- Sources Yolk, Salmon
- Deficiency: Rickets
- Function 1: Utilise cal cium/p hos phons
- Function 2: Build strong bones/teerh
vitamin E(fat Soluble):
- Sourcesivegetable oils, Nuts
- Deficiency: Abetallipoproteinemia
- Function 1: Antioxidant
- Function z: Enzymatic Regulation
vitamin K (Fat Soluble):
- Sources : Kale, Spinach
- Deficiency. vitamin K Deficiency
- Function 1: Regulation of blood clotting
- Function 2 : Response to injury
Minerals:
- Calcium:
- Sources: Milk, Cheese
- Deficiency: Osteoporosis
- Function 1: Helps heart be strong
- Function 2: Helps bones be strong
Potassium:
- Sources Squash, Potatoes Deficiency: Hypokalemia
- function 1 Balance of food/electrolyte
- Function 2 function of living cells.
Sodium:
- Sources: Celery, Beetroot
- Deficiency: Hyponatremia
- Function 1: Balance of fluids
- Function 2: Transmit nerve signals
Magnesium
- Sores Spinach, Almonds
- Deficiency: Magnesium Deficiency
- Function 1: For biochemical reactions
- Function 2: Heartbeat Steadiness
Phosphorus:
- Sources: Milk, Beans
- Deficiency: Rickets
- Function I: Growth of tissues
- Function 2 : Bone structure/strength
Chloride:
- Sources. Table Salt, Tomatoes
- Deficiency :Fluid loss (Dehydration, vomitting)
- Function 1: Osmotic pressure off fluids
- Function 2: Acid-base balance
Iron:
- Sources: Liver, Fish
- Deficiency: Anemia
- Function 1: Making Hemoglobin
- Function 2: Use of Oxygen
Manganese:
- Sources: Beans, Seeds.
- Deficiency: Manganese Deficiency
- Function 1: Fat/Carbs Metabolism
- Function 2: Blood Sugar Regulation
Iodine:
- Sources: Cranberries, Kelp
- Deficiency: Goiter
- Function 1: Thy rood functioning
- Function 2 : Conversion of food Energy
Chromium:
- Sources: Bread, Broccolis
- Deficiency: Diabetes
- Function 1: Fat/karbs Metabolism
- function 2: Insulin action
Fluoride:
- Sources: Walnuts, Cocoa Powder
- Deficiency: Tooth Decay
- Function 2: Mineralization of teeth
- Function 2 : Mineralization of bones
Copper:
- Sources: Potatoes, offal
- Deficiency: Wilson Disease
- Function 1: Proper Growth
- Function 2: Maintenance of organs
Selenium:
- Sources: Sardines, Beef
- Deficiency: Hypothyroidism
- Function 1: Making antioxidant enzymes
- Function 2: Preventing cell damage
Molybdenum:
- Sources: Beans, Lentils
- Deficiency: Molybdenum deficiency
- Function 1: Catalyst for enzymes
- Function 2: Catalyze amino acids with sulfur
Zinc:
- Sources: Oysters, Red meat
- Deficiency: Diarrhea
- Function 1: For immune system b work
- Function 2: Senses of smell and taste
Water: It is essential for life as we know it. Water forms about 70% of the human body. (2/3 of this water is in the cytoplasm of cells, and the other 1/3 in tissue fluid and blood plasma). Water acts as a solvent in metabolic reaction, transport media for substances between different parts of the body and regulates body temperature.
We lose water every day in urine, faeces, exhaled air and sweat that must be replaced by water in the diet.
Food is the fuel that drives life processes as energy is released from the different foods we eat during cellular respiration. The three main energy-providing organic molecules found in food are fats, carbohydrates and proteins, each having a different value.
A joule (J) is the SI unit of energy. The amount of energy contained in food is measured in either joules (J) or calories (cal). However, when talking about food, most people talk about calories. But, what is a calorie? A calorie is the amount of energy needed to raise the temperature of 1 cm3 (1 mL) of water 1 ºC.
In food labels, as joules and calories are small units, kilojoules and kilocalories are more frequently used to describe the energy values of food.
1calorie = 4.2 joules
Remember that not everyone needs the same amount of calories per day, as our energy requirements will be different according to our age, gender and life style, among others
Molecules | Energy contents (kJ/g) |
Fats | 39 |
Carbohydrates | 20 |
Proteins | 17 |
Food type | Example | Nutrients |
Meat, fish and eggs | Chicken, beef, cod | Proteins, lipids, iron and vitamin B2 |
Fruits and vegetables | Tomatoes, lettuce, apples, peas, carrots | Various vitamins and minerals. Carbohydrates. |
Starchy foods | Potatoes, rice, bread and pasta | Carbohydrates, proteins, vitamin B1 and iron. |
Sugars | Sugar, sweets, chocolates | Simple carbohydrates |
Fats and oils | Butter, olive oil | Vitamin A and D and in olive oil there is also vitamin E |
Pulses and nuts | Lentils, chick peas, almonds, walnuts | Various vitamins and minerals, proteins |
Milk and dairy | Milk, yogurt and cheese | Proteins, lipids, calcium and vitamins A, B and D |
In order to avoid health problems due to an inadequate diet, you should follow the following advice:
Eat a variety of foods : we need to eat food from all groups in order to maintain a balanced diet.
Eat the right amount each and every day: We don’t all have the same dietary needs. So it is important to eat the right amount of foods according to your sex, age and life style. As you should know, when you eat more calories than needed, the excess calories will be stored as extra fat in your adipose tissues.
You should eat fruit and vegetable on a daily basis: among other nutrients, fruits and veggies are a good source of vitamins, minerals and fibre. Dietary fibre is mainly indigestible plant cellulose which provides the bulk for faeces. Fibre will help push the food along the gut. A shortage of fibre can cause constipation and can also be a factor in the development of bowel cancer. Vitamins can be destroyed easily when heated. Also light or even oxygen in the air can destroy vitamins. That is why is important to include plenty fresh fruits and vegetables in your diet. Fruits and veggies also have antioxidants, which help prevent early aging of cells and cancer.
Alternate eggs, meat and fish as protein sources: Poultry and game are healthier than read meat, as red meat has more LDH cholesterol, ‘bad cholesterol’, which accumulates in your arteries causing cardiovascular diseases. Animal fats in general will have more LDH cholesterol than other sources of fats/oils, such as blue fish or nuts. It is also important to remember that too much animal protein could lead to an excess of uric acid in blood, which accumulates in joints causing pain.
What about eggs? How often should we eat eggs?, and how many? There are lots of discrepancy among nutritionists around the world on this issue Eggs are a very nutritious, as they not only have high quality and easily digested proteins, but also minerals, vitamins, etc. So, why do eggs sometime have such a bad reputation?. Let’s do our own investigation and try to come up with an educated answer!
Pulses (lentils, garbanzos and other beans), as well as nuts are very nutritious and should be eaten daily or often.
Better use vegetable oils than butter, as vegetable oils are a good source of HDL cholesterol and triglycerides, which our system needs. Olive oil is the best choice followed by sunflower seeds oil and then other vegetable oils.
Having a complete breakfast is important as it provides energy for the first hours of the day after fasting all night. It is better to eat smaller amounts of food regularly and more often, than big meals two or three times a day.
Drink 1.5 to 2 litres of water a day. Consume salt with moderation.
Avoid alcohol as it is toxic for the nervous system as well as for the liver.
Avoid ‘junk food’, such as processed food, sodas, and other non-nutritious snacks, containing lots of saturated fats, additives, flavour enhancers (such as MSG), and salt, among others.