Biology unit 7 and 8

Balanced Diet

Consists of all the food groups in the correct proportions

Carbohydrate Function

Source of Energy

Protien function

Growth and repair

Lipid function

Insulation and energy storage

Fibre function

Provides bulk (roughage) for the intestine to push food through

Vitamins function

needed in small quantities to mantain health

Water function

Needed for chemical reactions to take place in cells

Mineral  function

needed in small quantities to mantain health

Vitamin C function

Form an essential part of collagen protien which makes up skin hair gums and bones

Vitamin D function

Helps the body absorb calcium which is needed for Strong bones and teeth

Calcium function

Needed for strong teeth and bones and involved in blood clotting

Iron function

Needed to make haemoglobin, pigment in red blood cells which transports oxygen

Carbohydrates sources

Bread, cereal, pasta, rice, potatoes

Protien sources

Meat, fish, eggs, pulses, nuts

Lipids Sources

Butter, oil, nuts

Dietary Fibre sources

Vegetables, whole grains

Vitamins sources

Fruits and vegetables

Minerals sources

Fruits and vegetables, meats, dairy products

Water sources

water, juice, milk, fruit and vegetables

Vitamin C sources

Citrus fruits, strawberries, green vegetables

Vitamin D sources

Oily fish, eggs, liver, dairy products, sunlight

Calcium sources

Milk, cheese, eggs

Iron sources

Red meat, liver, leafy green vegetables - spinach

Scurvy Causes

Vitamin C deficiency, lack of vitamin C in body for over 3 months

Rickets causes

Severe vitamin D deficiency

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1)Mouth,
2)Oesophagus
3)Small Intestine
4)Duodenum
5)Ileum
6)Stomach
7)Large Instestine
8) Colon
9)Rectum
10)Anus
11)Salivary Gland
12) Liver
13)Gallbladder
14)Pancreas

Alimentary Canal

Organs in digestion through which food directly passes through

Ingestion

The taking in of substances, e.g food and drink, into the body

Digestion

The break down of food

Absorbtion

The movement of nutrients from the intestines into the blood

Assimilation

Uptake and use of nutrients by cells

Egestion 

The removal of undigested food from the body as faeces

Mouth Function

Ingests food and teeth break it down into smaller pieces during mechanical digestion

Salivary Glands function

Secretes saliva into the mouth, enzyme amylase in saliva begins to digest starch into maltose, saliva lubricates food for easy swallowing

Oesophagus Function

Tube which connests mouth to stomach, Contractions force food downwards 

Stomach function

churning of muscular stomach walls continues process of mechanical digestion, protease enzymes begin protein digestion, hydrochloric acid provides suitable pH for the enzymes and also destroys any pathogens in food

Liver Functions

Produces Bile which aids in digestion of fats and nuetralises stomach acids as it exits stomach

Gall Bladder Function

Bile is stored here before being released into duodenum via the bile duct

Pancreas Function

Amylase, Protease and lipase enzymes are produced here before being released into the duodenum

Duodenum function

Food enters the small intestine from the stomach here, acidic stomach contents are nuetralised by bile and become slightly alkaline, enzymes complete chemical digestion here

Ileum function

food and water are absorbed into the blood via villi in the lining of the ileum, part of the small intestine

Colon function

Remaining water is absorbed from food into the blood, solid waste left behind in the colon makes faeces

Rectum Function

stores faeces before egestion

Anus Function

Faeces leaves the body via anus, this is egestion

Physical Digestion

Breakdown of food into smaller pieces without chemical change to the food molecule

How does physical digestion help digestion overall

It increases the surface area of food for the action of enzymes in chemical digestion

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1)premolars
2)incisors
3)molars
4)canine

Enamel

Hard outer layer that protects the teeth

Dentine

Layer beneath the enamel which protects the nerves

Pulp

Soft internal tissue of tooth that contains nerve and blood vessels

Cement

Hard layer around the root that helps anchor it within the jaw

Where are teeth embedded?

In the bones and gums

Describe the structure of teeth

They have enamel…,dentine….,pulp….,nerves, blood vessels and cement…., the teeth is embedded in bone and gums

Function of incisors

bitting and cutting

Function of Canines

tearing, holding and biting

Function of molars/ premolars

ridges to chew and grind food

How does the stomach do physical digestion

Do stomach Churning: muscles contract to physically squeeze and mix the food with the strong digestive juices present

Functions of BILE

Alkali so it nuetralises HydroChloric coming from stomach as enzymes in small intestine have higher optimum pH than Stomach
Emulsification: breaks down larger droplets of fat into smaller ones, larger surface area allows lipase to chemically break down the lipid into fatty acids and glycerol quicker

How does Bile do physical digestion (name)

Emulsififcation

Chemical Digestion

Breakdown of large insoluable molecules into small soluble molecules

What is the role of chemical digestion in producing small soluble molecules which can be absorbed

Large insoluble molecules are unable to be absorbed through the wall of the small intestine
Small soluble molecules made from chemical digestion can easilly be absorbed into the surrounding capilleries

Amylase Function

breaks down starch to simple reducing sugars

Protease Function

Breaks down protien to amino acids

Lipase Function

Breaks down fats and oils to fatty acids and glycerol

Where is amylase secreted?

Salivary Gland and Pancreas

Where is Protease Secreted

Stomach and Pancreas

Where is Lipase Secreted

Pancreas

Where does Amylase Acts

Mouth and duodenum

Where does Protease act? (specific)

Stomach and duodenum

Where does Lipase act

Duodenum

Function of Hydrochloric Acid in Stomach

Kill harmful micro-organisms in food as it denatures the enzyes in their cells
Ensure conditions remain in optimum pH (very low) for its enzymes to ensure optimum enzyme activity eg Pepsin has optimum pH of 2

Describe the digestion of starch in the digestive system

Amylase breaks down starch to Maltose,
Maltase breaks down Maltose to glucose on the lining of the epithelium lining on the small intestine

Describe the digestion of protien

Pepsin breaks down protien in the acidic conditions of the stomach
Tryspin breaks down protien in the alkaline conditions of small intestine

How does Bile make food coming from the stomach suitable

Bile is an alkali mixture that nuetralises the acidic mixture of food and gastric juices entering the duodenum from the stomach to provide a suitable pH for enzyme action

Where are nutrients absorbed?

Small intestine

Where is water absorbed in the digestive system

Mostly small intestine but some is also from the colon

Explain the significance of Villi and Microvilli of increasing surface area in the small intestine

Massively increase Surface area, Allowing absorbtion to take place faster and more efficiently, 

Structure of Villus

one cell thick wall- fast absorbtion, microvilli on surface- further increase surface area, finger like projections

Role of Capilleries in Villi

Transport glucose and amino acids away from small intestine in the blood

Lacteal role in Villi

Run through the center of the villi to transport fatty acids and glycerol away from the small intestine in the lymph

Function on Xylem

Transport water and mineral ions and support the plant

Function of Phloem

Transport Sucrose and Amino Acids

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1) Phloem
2) Xylem
3) Vascular Bundle

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1)Phloem
2)Xylem
3)Vascular Bundle

Adaptations of Xylem

Thick walls with lignin
No cell content
Cells joint end to end with no cross walls to form a long continuous tube

How does having thick walls made of lignin help the xylem perform its function?

Helps support the plant

How does having no cell content help the xylem perform its function?

Allows free passage of water

How does cells joint end to end with no cross walls to form a long continuous tube help the xylem perform its function?

Allows free passage of water

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Root hair cell

Function of Root hair cells

Absorb water and minerals from the soil through osmosis

How does water reach the mesophyll cells? (pathway)

Root hair cells, Root cortex cells, Xylem, Mesophyll cells

Plan an experiment to test the pathway of water in plants using a dye

Place a plant stem into a beaker of water that has had a stain added to it
Leave for a few hours until the leaves of the plant turn the same colour as the dyed water- This shows that the dye has travelled all the way up the xylem
Cut a cross section of the stem and view the position of the coloured dye, which will correspond with the location of the xylem vessels

Transpiration

The loss of water vapour from leaves

How does transpiration happen

Water evaporates from the surface of the mesophyll cells into the air spaces then diffuses out of the leaves through the stomata as water vapour

How does temperature effect transpiration and why?

Increases the rate of transpiration as particles have higher kinetic energy so transpiration occurs at a faster rate as water molecules evaporate and diffuse at a faster rate

How does humidity effect transpiration and why?

Decreases transpiration as when the air is saturated with water molecules the concentration gradient is lower so less diffusion out so less water is lost

How does wind speed effect transpiration and why?

Increases transpiration as high wind speed moves the water molecules arround the leaf which have recently transpired so there is a higher concentration gradient increasing water loss

Why does wilting happen

If more water evaporates away from the leaf then gained in the soil wilting will happen

How does wilting happen

Plant cells lose water so lose turgidity so the strength of the cell walls can no longer support the plant and it starts to collapse

How does water move up in xylem

Water moves upward in the xylem due to transpiration pull that draws up a column of water molecules held togethor by forces of attraction between water molecules