B7 - Human Nutrition

B7.1 Diet
What is meant by a balanced diet?
-​ A balanced diet is a diet consisting of the right proportions of every type of nutrient in suitable size
portions. There are 7 nutrients needed in a balanced diet, carbohydrates, fats and oils, proteins vitamins,
mineral ions, fiber and water

State the principal dietary sources and describe the importance of:
(a). Carbohydrates
-​ Primary source of energy, proteins are broken down to release energy from respiration
-​ Examples: potatoes, rice, bread

(b). fats and oils

-​ Fats insulate the body, helping reduce fluctuations in our body temperature
-​ Store energy
-​ For making cell membranes
-​ Examples: oil, butter, margarine

(c). Proteins
-​ For growth and repair of tissues, like muscle or skin
-​ Examples: chicken, meat, fish

(d). vitamins, limited to C and D

-​ Vitamin C is vital for the production of Collagen
-​ What is Collagen? Protein in blood vessels and skin for repairing bones and teeth
-​ Examples: citrus fruits(oranges, lemons, peppers)

-​ Vitamin D helps absorb calcium + phosphorus

-​ Examples: oily fish (e.g. salmon, sardines and mackerel), eggs yolks, sun light

(e). mineral ions, limited to calcium and iron

-​ Calcium is needed for healthy bones and teeth
-​ Examples: dairy(milk, cheese, yoghourt), green vegetables(kale, broccoli)

-​ Iron is needed to make haemoglobin

-​ What is Haemoglobin? a protein responsible for transporting oxygen around the body
-​ Examples: red meats, liver, nuts, dried fruit

(f). fibre (roughage)

-​ Adds bulk and ‘roughage’ to your food so that your intestines can push it along your alimentary canal
-​ Examples: wheat(TRIGO), whole grain bread(PAN INTEGRAL), oats(AVENA)
(g). Water
-​ Necessary for chemical reactions in cells
-​ For waste removal
-​ For temperature regulations

Why do you get SCURVY and what does it mean?

-​ a type of disease caused by vitamin C deficiency when you have bleeding and swollen gums as your
body can't produce enough collagen

Why do you get RICKETS and what does it mean?

-​ a type of disease caused by vitamin D deficiency where your bones get malformed

B7.2 Digestive system

a)​ Alimentary canal: mouth,
oesophagus, stomach, small intestine,
large intestine

b)​ Associated organs: salivary

glands, pancreas, liver, gallbladder

Small Intestine: Duodenum, Ileum

Large Intestine: Colon, Rectum, anus

Describe the functions of the organs of the digestive system listed in 7.2.1, in relation to:
(a). ingestion – the taking of substances, e.g. food and drink, into the body
(b). digestion – the breakdown of food
(c). absorption – the movement of nutrients from the intestines into the blood
(d). assimilation – uptake and use of nutrients by cells
(e). egestion – the removal of undigested food from the body as faeces
Describe the functions of the regions of the alimentary canal listed above, in relation to ingestion,
digestion, absorption, assimilation and egestion of food

Mouth:
-​ The mouth contains saliva, which is secreted from the salivary glands. Saliva contains salivary
amylase – an enzyme that breaks down carbohydrates (chemical digestion). The mouth also
contains teeth, that cut, chew and grind food (mechanical digestion). Food is formed into a bolus,
which is then swallowed.

-​ The mouth is used for ingestion, as well as both mechanical and chemical digestion.

-​ Since the salivary glands use nutrients to produce saliva, this can be considered a site of
assimilation.

Oesophagus:
-​ The swallowing of food causes it to move from the mouth to the stomach through the
oesophagus, by peristalsis.

-​ Peristalsis → the involuntary constriction and relaxation of the muscles of the intestine or another
canal, creating wave-like movements which push the contents of the canal forward.

Stomach:
-​ The stomach is an organ containing gastric juices (mainly hydrochloric acid and protease
enzymes). The acidity (pH2) kills bacteria and the proteases digest proteins. The stomach also
churns the food in it. It releases small amounts of food at a time into the duodenum, storing the
rest.

-​ Mechanical and chemical digestion occurs in the stomach.

Pancreas:
-​ Secretes pancreatic juices to the duodenum.
-​ As the pancreas uses nutrient molecules to do this, this can be considered a site of assimilation.

Gall bladder:
-​ Stores bile which is produced by the liver, and secretes it to the duodenum.

Small Intestine:
-​ The Pancreas and the gall bladder are connected to the duodenum by ducts. Pancreatic juices
and bile (stored in gall bladder) are transported to the small intestine via these ducts. Pancreatic
juices contain proteases, lipases (fat-digesting enzymes), amylases and sodium
hydrogencarbonate (which neutralises the acid from the stomach).

-​ Bile, produced by the liver and stored in the gall bladder, contains bile acids, also known as bile
salts – which emulsify fats. Bile is also alkaline, which helps neutralise stomach acids.

-​ The epithelial lining of the rest of the small intestine secretes yet more enzymes which breakdown
maltose and peptides. The jejunum and ileum have a huge surface area due to the villi present,
allowing a greater amount to be absorbed at a time.
 -​ The small intestine is a site of both chemical digestion and absorption.
The large intestine:
-​ The main function of most of the large intestine is to reabsorb the water from the undigested food.

-​ The last part of the large intestine, called the rectum, stores faeces until it is egested.
Anus:
-​ The anus is the site of egestion – it has sphincter muscles that control when faeces is egested
from the body.

B7.3 Digestion
What is Physical/Mechanical Digestion?
-​ Physical digestion as the breakdown of food into smaller pieces without chemical change to the food
molecules

What is Chemical Digestion?

-​ Chemical digestion as the breakdown of large insoluble molecules into small soluble molecules

Why is Physical/Mechanical Digestion important?

-​ Physical digestion increases the surface area of food for the action of enzymes in chemical digestion

Why is Chemical Digestion important?

-​ Chemical digestion produces small soluble molecules that can be absorbed into the blood and then
nutrients are absorbed and utilised by the cells.

Describe the functions of enzymes as follows:

(a). amylase breaks down starch to simple reducing sugars
(b). proteases break down protein to amino acids
(c). lipase breaks down fats and oils to fatty acids and glycerol

What is an enzyme?
-​ proteins that are involved in all metabolic reactions, where they function as biological catalysts

AMYLASE QUESTIONS:
-​ Where is it created?
-​ Its functions
-​ Where is the site of action

PROTEASE QUESTIONS:
-​ Where is it created?
-​ Its functions
-​ Where is the site of action

LIPASE QUESTIONS:
-​ Where is it created?
-​ Its functions
-​ Where is the site of action
 Describe the functions of hydrochloric acid in gastric juice(2)
-​ The hydrochloric acid kills harmful organisms that make it into the stomach in food by denaturing their
enzymes
-​ Provide an acidic pH for optimum enzyme activity of proteases in the stomach
What is Bile?
-​ Bile is an alkaline mixture that…neutralises the acidic mixture of food and gastric juices entering the
duodenum from the stomach to provide a suitable pH for enzyme action in the small intestine

What is Bile’s role in digestion and importance?

-​ Bile breaks down large fat droplets into smaller ones (EMULSIFICATION)
-​ Emulsification increases the surface area of fat droplets for lipase to break down fats

Where is bile produced(synthesised), stored and released

-​ Produced(synthesised) → liver
-​ Stored → gallbladder
-​ Released → small intestine

What is Peristalsis
-​ Peristalsis → the involuntary constriction and relaxation of the muscles of the intestine or another canal,
creating wave-like movements which push the contents of the canal forward.
-​ Helps move food along the alimentary canal
-​ Starts in the oesophagus

Visking Tube Experiment

​
B8 - Transport in Plants
B8.1 Xylem and phloem
(a). xylem vessels – transports water and mineral ions, taken up from the soil by the roots, to the rest of the plant,
and provides structural support to the plant

-​ One way only

-​ No end wall between cells

-​ Outer cells are not living

-​ Thick walls made of Lignin

-​ Lignin: a complex organic polymer that is deposited in the cell walls of xylem vessels, contributing to their
rigidity and strength

(b). phloem vessels – transport of sucrose and amino acids made by the plant from photosynthesizing leaves to
non-photosynthesizing regions in the root and stem

-​ 2 way movement

-​ Has end walls(sieve plates→act like valves)

-​ Cells are living but need support

VASCULAR BUNDLE: part of transport system in vascular plants that consists of xylem and phloem
tissue.(XYLEM + PHLOEM)
Identify in diagrams and images the position of xylem and phloem as seen in sections of roots, stems and
leaves of non-woody dicotyledonous plants

CROSS SECTION OF ROOTS:

CROSS SECTION OF STEMS:

CROSS SECTION OF LEAVES:

B8.2 Water uptake
Identify in diagrams and images root hair cells and state their functions
-​ a root hair cell is a specialised cell found in roots of plants that is specially adapted to absorb water and
minerals from the soil
-​ these cells have root hairs which are extensions or outgrowths of epidermal cells

What are root hairs in root hair cells for?

-​ the large surface area of root hairs increases the uptake of water and mineral ions because by increasing
the surface area you increase the rate of osmosis and active transport
Why does Osmosis happen?
-​ This happens because soil water has a higher water potential than the cytoplasm of the root hair cell

Outline the pathway taken by water through root, stem and leaf as: root hair cells, root cortex cells,
xylem, mesophyll cells
B8.3 Transpiration
Describe transpiration
-​ the loss of water vapour(through diffusion)from leaves
-​ water evaporates from the surfaces of the mesophyll cells into the air spaces and then diffuses out of the
leaves through the stomata as water vapour

Investigate and describe the effects of variation of temperature and wind speed on transpiration rate

The water bubble goes towards the plants(plant absorbs water)

Results
●​ The further the bubble travels along the tube, the more water has been taken up by the plant
●​ We would expect that as light intensity increases, the bubble will travel further during the 30 minute
time period
○​ Transpiration rate increases with light intensity because more stomata tend to be open in bright
light in order to maximise photosynthesis

Investigating other factors

●​ The same technique can be used to investigate the effect of other environmental factors:
○​ Temperature can be investigated by setting up a potometer in rooms at different temperatures
○​ Wind speed can be investigated using an electric fan to generate air movement

RATE OF TRANSPIRATION=DISTANCE MOVED BY AIR BUBBLE(mm)/TIME(min)

BUBBLE MOVES TOWARDS PLANT ←

Explain the effects on the rate of transpiration of varying the following: temperature, wind speed and
humidity
 Transpiration Stream
●​ During transpiration water molecules evaporate from the surface of mesophyll cells
in the leaf before diffusing out of the leaf through the stomata
●​ When water is lost from leaves in this way, more water is drawn up the xylem to
replace it; this movement of water in the xylem from the roots to the leaves of plants is
thetranspiration stream

●​ The transpiration stream is maintained by forces of attraction, known as cohesion,

between water molecules as follows:
○​ Water is lost from the leaves during transpiration
○​ More water molecules are drawn into the leaf by osmosis
○​ The moving water molecules 'pull' neighbouring water molecules up the xylem
behind them due to forces of attraction between the molecules
○​ A continuous column of water moves up the xylem
●​ The upward force generated by transpiration in the leaves is transpiration pull
5 Explain how and why wilting occurs

B8.4 Translocation
Describe translocation
-​ as the movement of sucrose and amino acids in phloem from sources to sinks
Describe Sources and Sinks
(a). sources as the parts of plants that release sucrose or amino acids
(b). sinks as the parts of plants that use or store sucrose or amino acids
B9 - Transport in Animals
B9.1 Circulatory systems
What is a circulatory System
-​ as a system of blood vessels with a pump and valves to ensure one-way flow of blood

-​ 2 Describe the single circulation of a fish

-​ 3 Describe the double circulation of a mammal
-​ 4 Explain the advantages of a double circulation
B9.2 Heart

1 Identify in diagrams and images the structures of the mammalian heart, limited to:
muscular wall,
- septum(wall separating oxygenated and deoxygenated blood)
- left and right ventricles,
- left and right atria,
- one-way valves
- and coronary arteries

-​ Chambers contract for blood to flow

ATRIOVENTRICULR VALES (MORE TO THE SIDES)

SEMILUNAR VALVES(MIDDLE)
Coronary arteries

Muscular Wall

→ State that blood is pumped away from the heart in arteries and returns to the heart in
veins

State that the activity of the heart may be monitored by:

- ECG (electrocardiogram),
- pulse rate
- and listening to sounds of valves closing

4 Investigate and describe the effect of physical activity on the heart rate
Coronary Heart Disease
Describe coronary heart disease in terms of the blockage of coronary arteries and state the

Possible risk factors of coronary heart disease including:

- diet(high saturated fats) → increase cholesterol
- lack of exercise,
- stress,
- smoking, → increases blood pressure + increases likelihood of clots forming in the arteries
- genetic predisposition,
- age
- and sex

6 Discuss the roles of diet and exercise in reducing the risk of coronary heart disease
How to reduce the risk coronary heart disease
-​ Quit smoking
-​ Maintain a healthy diet with reduced animal fats
-​ Exercise regularly
Describe the functioning of the heart in terms of the contraction of muscles of the atria and ventricles and
the action of the valves

VALVES → (stop the backflow of blood)\\