IB Exam (Option D)

Define Nutrition

the supply of nutrients

U: Why must nutrients be included in diets?

because essential nutrients cannot be synthesized by the body

U2: What are Dietary Minerals?

essential chemical elements

U3: What are Vitamins?

chemically diverse carbon compounds that cannot be synthesized by the body

U4: Some fatty acids and some amino acids are ________.

essential

U5: In relation to Digestion, what affects proteins?

the lack of essential amino acids

U: What causes Malnutrition?

• deficiency

• imbalance

• excess of nutrients in diet

U: What Controls Appetite?

a centre in the hypothalamus

U8: Overweight individuals are more likely to suffer ___________ and ____ ______

• hypertension

• type II diabetes

U: What can Starvation lead to?

body tissue breakdown

What is Ascorbic Acid?

Vitamin C

A1: Production of ascorbic acid by some mammals, but not others that need a dietary supply

• needed for the synthesis of collagen fibres in many body tissues including skin and blood vessel walls

• vitamin C is an essential aa so must be obtained externally through diet

• Scurvy - deficiency in vitamin C

• artificial scurvy unsuccessful in other species due to them having proteins to synthesize vitamin C

• scurvy also occurs in guinea pigs, chimps and apes

A: Cause and treatment of phenylketonuria (PKU)

• phenylalanine - essential aa

• tyrosine - non-essential aa

• phenylalanline (via phenylallanine hydroxylase) → tyrosine

• phenylketonuria - overabundance of phenylalanine

  • mutation from recessive gene produces low or no phenylalanine hydroxylase

A: Lack of Vitamin D or calcium can affect bone mineralization and cause rickets or osteomalacia

• low vitamin D = low calcium absorption = low calcium count

• vitamin D deficiencies = calcium deficiencies

• osteomalacia - softened bones due to inadequate bone materialism resulting from calcium not being absorbed

• rickets - osteomalacia in kids

• vitamin D is found in oily fish, dairy, and liver

• can be synthesized with UV rays (sunlight)

• liver stores vitamin D during summer for winter

A: Breakdown of heart muscle due to anorexia

condition where individual does not eat enough food even though it is available

• Once glycogen and fat reserves are used up, body tissues have to be broken down and used in respiration

A: Cholesterol in blood as an indicator of the risk of coronary heart disease

• only cholesterol in LDL (low-density lipoprotein) is related to CHD

• reducing dietary cholesterol barely affect blood cholesterol = small effect on CHD

• since liver can synthesize cholesterol, diet is no the sole source

• genetics are more important than diet

• positive correation between high saturated fats + high cholesterol intake

• suggests high sat fats

S: Determination of the energy content of food by combustion

• since it take 4.2 J of energy to heat 1 mL of water by 1 degree

• energy content of a food ( J g) = (°C×mL×4.2J)÷(g)

• food calorimer are more accurate since it traps all heat

S: Use of databases of nutritional content of foods and software to calculate intakes of essential nutrients from a daily diet.

RDA = recommended daily amount

table shows some of the nutrients in 50 g of salted cashew nuts, the recommended daily amount (RDA) of the nutrient for a 14-18 year-old boy and the percentage of this that the cashew nuts contain:

U: What controls the secretion of digestive juices?*

Nervous and hormonal mechanisms

exocrine:

• glands that secrete digestive juice are exocrine

• secrete through a duct onto to the surface of the body or into the lumen of the gut

U: The volume and content of gastric secretions are controlled by…

nervous and hormonal mechanisms

• sight or smell of food send nerve impulses to parietal cells

U: Acid conditions in the stomach favour… Tell me more about it.*

some hydrolysis reactions and help to control pathogens in ingested food

• Gastric juice is secreted by cells in the epithelium that lines the stomach

• Hydrogen ions are secreted by the parietal

  cells

• (pH 13),

• hydrolysis by pepsin o peptide bonds in polypeptides.

• Pepsin is secreted by chie cells in the inactive orm o pepsinogen; stomach acid converts it to pepsin.

U: The structure of cells of the epithelium of the villi is adapted to the absorption of food*

Microvilli

• protrusions of the apical (relating to apex) plasma membrane

• (about 1m by 0.1m)

• increase the surface area of plasma membrane exposed to the digested foods in the ileum and therefore food absorption.

Mitochondria  there are many scattered through the

cytoplasm, which produce the ATP needed orabsorption o

digested oods by active transport.

U: The rate of transit of materials through the large intestine is positively correlated with their fibre content*

• dietary fibre - substances that cannot be digested by the intestestines so they must be egested

• Cellulose, lignin, pectin and chitin are all dietary fibres

A: The reduction of stomach acid secretion by proton pump inhibitor drugs

• secretion of acids into stomach is controlled by H⁺/K⁺-ATPase

• exchange H⁺ in cytoplasm for K⁺ in stomach

• gradient of H⁺ can reach up to 3 million

• mucus protects lining of stomach

• if lining breaks, it causes an ulcer

• acid reflux - entry of acid stomach contents to the esophagus, causing the pain known as heartburn

• proton-pump inhibitors or PPIs -

A: Dehydration due to cholera toxin

1. Vibrio cholerae releases toxin

2. toxin binds to receptor on intestinal cells

3. V. cholera releases toxins

4. toxin enters cell via endocytosis

5. toxin triggers release of HCO₃⁻ and Cl⁻

6. water follows due to osmosis

7. causes watery diarrhea

8. water in blood replaces water

9. causes severe near fatal dehydration

A: Helicobacter pylori infection as a cause of stomach ulcers

• Stomach Ulcers - open sores caused by partial digestion of the stomach lining by the enzyme pepsin and hydrochloric acid in gastric juice

• emotional stress and excessive acid secretion were regarded as the major contributory factors

• now about 80 percent of ulcers are now considered to be due to infection with bacterium Helicobacter pylori

S: Identify this cell. How did you know it was that cell?

Exocrine Pancreatic Gland Cell

• large amounts of Rough Endoplasmic Reticulum, Golgi apparatus and secretory vesicles