Biology 2 - Topic 3

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What are fossils?
It is a trace that animals and plants lived a long time ago.
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Give 3 ways in which fossils can be formed.
1. Gradual replacement by minerals. 2. Forms casts and impressions. 3. Forms preservation in places where no decay happens.
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Describe how gradual replacement by minerals occurs.
Things like: teeth, shells and bones don't decay easily so can last ages when buried. They replace minerals eventually that forms a rock-like substance. They stay in the rock and are eventually dug up.
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Describe how casts and impressions are formed.
When organisms are buried in soft material: clay, the material hardens around the organism leaving a cast. Things like footprints can be make an impression.
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Describe how preservations are formed when no decay happens.
The conditions are suitable for microbes to work, glacier as it is too cold.
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Where are fossils found?
In layers of rocks.
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What 3 things do fossils found in rock layers tell us?
1. What the creature looked like. 2. How long ago they existed - the deeper the rock, the older the fossil. 3. How they evolved - studying similarities and differences between fossils and rock ages; we can see how species have changed.
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The fossil record is...
...incomplete.
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Why are fossil records incomplete? 3 things.
1. Very few plants or animals actually turn into fossils - they decay. 2. Some body part, like soft tissue, decay completely. 3.Some fossils are yet to be discovered.
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What is the pentadactyl limb?
It is a limb with five digits.
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What does the pentadactyl limb provide?
Evidence for evolution.
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Give 3 organisms that have pentadactyl limbs?
Mammals, reptiles and amphibians.
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What is the similarity of pentadactyl limbs?
They have bone structure that provides evidence that species with pentadactyl limbs have evolved from a common ancestors. It is unlikely that they had similar bone structure.
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What is growth.
An increase in size and mass.
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How can you measure growth? 3 things.
1. Size 2. Wet mass. 3. Dry mass.
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What is size?
The measurements of: height, width and circumference.
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What is wet mass?
The mass of the organism's body and how much water in the body it has - the mass varies from day to day.
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What is dry mass?
The mass of an organism with no water in it's body - this doesn't vary.
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What does growth involve?
1. Cell differentiation. 2. Division 3. Elongation.
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What do plants and animals do with cell differentiation, division and elongation?
They grow and develop.
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What is cell differentiation?
The process by which a cell changes to become specialised for its job.
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What is cell division?
Cell division is mitosis.
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What is cell elongation?
Where a plant cell expands, making the cell bigger and the plant to grow.
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Which organism does cell elongation occur in?
In only plants.
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Plants and animals grow...
...differently.
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How does growth happen in animals?
By cell division. Animals grow while they are young and reach full growth when they stop growing. When you are young, cell divides quickly but, when you are an adult; your cells divide for repair. They replace the old and damaged cells.
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What does this mean?
That cell differentiation is lost at an early stage.
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How does growth happen in plants?
Plants grow continuously. Plants continue to differentiate to develop new part: branches, leaves, roots. Growth in height is by cell elongation. Cell division happens at the: tips of roots and shoots.
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What are interpret percentile charts used for?
For growth data.
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What are growth charts used for?
To assess a child's growth over time so that overall pattern in development is seen and, any problems highlighted: obesity pr dwarfism.
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What tree measurements are taken?
1. Length. 2. Mass. 3. Head circumference.
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Cells are made up of?
Tissues, organs and systems.
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What have large multicellular organisms have?
They have different systems for exchanging and transporting materials.
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What are tissues?
A group of similar cells that work together to carry out a particular function - e.g. muscle tissue.
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What are organs?
A group of different tissues that work together to perform a particular function - e.g. the heart.
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What are organ systems?
A group of organs working together to perform a particular function - e.g. circulatory system.
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The heart has 4 what?
Chambers and blood vessels.
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What does the right side of the heart have? 5 things.
Pulmonary artery, vena cava, right atrium, valves and right ventricle.
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What does the right side of the heart recieve?
The deoxygenated blood through the vena cava.
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What happens to the deoxygenated blood?
It moves trough the right ventricle that pumps the lungs via the pulmonary artery.
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What does the left side of the heart have? 5 things.
Aorta, pulmonary veins, valves, left ventricle and left atrium.
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What does the left side of the heart receive?
The oxygenated blood.
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What happens to the oxygenated blood?
The oxygenated blood moves through the left ventricle and pumps round the whole body via the aorta.
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What is the difference between the left and right ventricle?
The left ventricle has thicker walls as it needs more muscles to pump blood around the whole body whereas, the right ventricle only has to pump to the lungs.
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What do valves do?
Prevent back-flow of the blood.
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What is the circulatory system?
Carrying blood around the body.
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Give the 4 things in the blood.
Red and white blood cells, plasma and platelets.
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What do red blood cells do?
Carries blood from the lungs to the cells in the body.
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What do red blood cells do?
They have biconcave disc shape to give a large surface area for absorbing oxygen.
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What do they contain?
Haemoglobin - contains a lot of iron.
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What happens to the haemoglobin when it gets to the lungs?
The haemoglobin combines with oxygen to become oxyhaemoglobin.
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What happens in body tissues with haemoglobin?
The oxyhaemoglobin releases the oxygen to the cells.
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What do red blood cells not have and why?
They don't have a nucleus so, there is more room for haemoglobin.
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What can a lack of iron do?
Cause a type of anaemia where the blood cannot carry enough oxygen.
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What do white blood cells do in the body?
They defend against diseases.
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What does white blood cells look like?
They change shape to take in unwanted microorganisms.
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What do white blood cells do it fight microorganisms?
They produce antibodies and antitoxins to neutralise toxins made by microorganisms.
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What does a low white blood cell count mean?
It could increase the risk of infections.
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What does a high white blood cell count mean?
That you may have an infection like: leukaemia (cancer in the blood).
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What do platelets do?
Help blood clot.
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What do platelets look like?
They are small fragments of cells.
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How do they help blood clot?
They help the wound to clot so it stops your blood from flooding out and, to stop microorganisms getting in.
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What does a lack of platelets mean?
They can cause excessive bleeding and bruising.
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What are plasmas?
They are a liquid that carries everything in the blood.
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What do they look like?
A pale yellow liquid keeps the blood fluid.
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What do they transport?
Red and white blood cells and platelets.
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What are glucose and amino acids?
They are nutrients.
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What happens to glucose and amino acids?
They are absorbed from the gut and taken into the body cells.
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What does carbon dioxide have to do with plasmas?
Carbon dioxide is a waste product in every cells that is transported from the blood to the lungs, where it is removed.
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What happens with urea?
This is a waste product that is formed in the liver. The blood transports it to the kidneys, where it is removed.
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What happens with hormones?
They are transported from the glands to target the organs.
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What happens with antibodies and antibiotics?
They are produced by the white blood cells.
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What are blood vessels designed for?
They are designed for their function.
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Give 3 types of blood vessels.
1. Arteries. 2. Capillaries. 3. Veins.
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What are arteries?
These carry blood away from the body.
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What are capillaries?
Theses are involved in the exchange of materials with the tissues.
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What are veins?
These carry blood into the heart,
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What do arteries do?
Carry blood under pressure.
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Describe what happens when arteries take blood away from the body.
The heart pumps the blood out at high pressure so the artery walls are strong and elastic.
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Why do the walls have to be thick?
Because, compared to the size of the hole down the middle - lumen - they contain thick layers on muscle to make them strong.
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Give two things you would pick out when annotating a diagram for arteries.
1. Lumen. 2. Elastic fibers and smooth muscles.
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Where are capillaries to arteries?
They branch off arteries.
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Capillaries are...
...really small.
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Describe what capillaries look like.
They are very small and you cannot see them with the naked eye.
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Describe how capillaries work.
They carry blood really close to every cell in the body to exchange substances with them
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What are the walls like in capillaries and why?
They have permeable walls so the exchange substances are carried with them.
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What do they supply and what do they take away?
They supply food and oxygen and, take away carbon dioxide.
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What are the walls usually like in capillaries and why?
They are only one cell thick which increases the rate of diffusion by decreasing the distance over which it occurs.
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Give three things that would be labeled in a diagram for capillaries.
1. Thin wall - one cell thick. 2. Small lumen. 3. Nucleus.
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Where are the veins compared to capillaries?
Capillaries join up to veins.
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What are the walls like in the veins?
They veins don't have as thick walls compared to arteries as the blood is pumped at a low pressure.
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What is the lumen like compared to arteries?
It is a bigger lumen which means that the veins can help the blood flow even though there is a lower pressure.
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Why do veins have valves?
To keep the blood flowing in the right direction.
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Give two things that would be in labeled in a diagram for veins.
1. Large lumen. 2. Elastic fibres and smooth muscle.
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What does digestion mean?
The breakdown of food into soluble productions that is then absorbed into the body.
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Where does digestion occur?
In the digestive system.
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How is the food broken down?
The food is catalysed by enzymes.
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What are big molecules and give 3 examples.
They are molecules that are too big to pass through walls of the digestive system. 1. Starch. 2. Proteins. 3. Fats.
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What are small molecules and give 3 examples.
They are molecules that can pass through walls of the digestive system. 1. Sugars. 2. Amino acids. 3. Fatty acids.
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How does the digestive system break down big molecules? Give 3 examples.
They break them down into smaller molecules. 1. Carbohydrases (amylase) digest starch into sugars. 2. Proteases (pepsin) digest proteins into amino acids. 3. Lipase digests fats to fatty acids to glycerol.
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Describe what happens at the mouth in the digestive system.
Food is moistened with saliva from the salivary glands. The salivary glands produce amylase enzymes that breaks down starch. Food is chewed to form a ball of food (bolus) before being swallowed.
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Describe what happens at the oesophagus in the digestive system.
The oesophagus is a tube where the food is taken from the mouth and into the stomach. The oesophagus is lined with muscles that contract to help the ball of food move along by the peristalsis.
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Describe what happens at the liver.
This is where bile is produced, and the bile neutralises stomach acid and emulsifies fats.
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Describe what happens at the gall bladder.
This is where the bile is stored before it is released into the small intestine.
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Describe what happens at the stomach in the digestive system.
It pummels the food with its muscular walls. It produces the protease enzymes, pepsin. It produces hydrochloric acid to kill bacteria and to give the right pH the protease enzyme can work at.
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Describe what happens at the pancreas.
This produces protease and amylase and lipase enzymes. It releases these into the small intestine.
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Describe what happens at the small intestine in the digestive system.
It produces protease, amylase and lipasr enzymes to complete digestion. This is also where food is absorbed out of the digestive system into the body.
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Describe what happens at the large intestine in the digestive system.
Where excess water is absorbed from the food.
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What can you use to test for a model of the gut?
The visking tubing.
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What experiment could you do to show the model of the gut?
Using iodine to test for starch and Benedict's test for sugar.
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Describe step 1.
Add the same number of starch suspension and 0.25% of amylase solution to the visking tubing. Rinse the outside of the tubing.
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Describe step 2.
Put the visking tubing into a boiling tube with distilled water in it.
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Describe step 3.
Test a drop of water from the visking tubing straight away with some iodine. Take 5 drops to test for Benedict's reagent, and record the colour each time.
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Describe step 4.
Leaving the boiling tube for 15 minutes.
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Describe step 5.
Test the water again and the Benedict's reagent, and record the colours.
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Describe step 6.
Repeat the experiment using other concentrations if the amylase: o.5%, 1% etc..
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Describe how you would use the Benedict's reagent.
Add 5 drops of water to a test tube and a drop of Benedict's reagent, and put the test tube into a beaker of boiling water. Record the colour after 2 minutes. It starts off: blue, green, yellow, orange then, brick-red.
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Why would Benedict's reagent change colours?
if there is sugar present. The further the colour changes to brick-red, the more sugar is present.
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What is the colour of iodine?
Orangey-brown.
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Why might the colour of the iodine stay orangey-brown?
Because the sugar molecules might be too big to pass through the visking tubing and into the water,
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Why might the colour of Benedict's reagent change?
Because the starch has broken down by amylase to sugar in the visking tubing. The sugar molecules are small enough to pass through the visking tubing and into the water.
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What happens when the concentration increases?
The amylase increases, the Benedict's reagent changes colour to show there is more starch to be broken down by amylase to sugar. There are more active sites available to break down the starch to sugar.
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What happens until it gets to it optimum concentration?
The reaction won't increase because all the active sites are full.
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Describe the graph.
There is a steady increase until it gets to it's optimum temperature where the line corners off.
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Give 4 advantages of using the visking tubing as a model as the gut.
1. It is a good model of the gut as it only lets out smaller molecules. 2. It is cheaper. 3. Easier. 4. Good enough to see how the digestion works.
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Give 3 disadvantages of using the visking tubing model as the gut.
1. Isn't the same as the gut as the gut is longer has a bigger surface area. 2. The digestion and absorption will be different. 3. The visking tubing is not exactly the same as the gut.
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What do peristalsis involve?
Longitudinal and circular muscles.
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Where are the muscular tissues in the digestive system?
They are all the way down the digestive system.
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Where are the longitudinal muscles?
Down the left of the gut.
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Where are the circular muscles?
They run in circles around the gut.
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What is the job of the muscles?
They are to squeeze the food along.
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What are peristalsis?
It is the squeezing action in the gut by the longitudinal and circular muscles.
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What do waves of circular muscle contractions do?
Push the food along the gut.
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What do waves of longitudinal muscle contraptions do?
Run slightly to help keep the food in a ball.
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Is bile acidic, neutral or alkaline?
Bile is alkaline.
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Where do enzymes best for in alkaline environments? What does it do?
The small in intestine. This emulsifies fats.
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What do emulsifies fats mean?
The fats break down into tiny droplets. This gives a much bigger surface area of fat for the enzyme lipase to work - digests faster.
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What does villi provide?
A really big surface area.
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What does the small intestine have covered in?
Millions of little villi.
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Give 3 features that make absorbing digestion food into the blood stream really efficiently.
1.Has a big surface area so the digested food is absorbed much more quickly into the blood.2.Single layer of surface cells so that the digestion diffuses quickly or short distance.3.Good blood supply via capillary network to ensure quick absorption.
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What are functional foods? Give an example.
It has a health benefit beyond basic nutrition. E.g. It could prevent diseases.
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What are probiotics?
They are live bacteria and are similar to bacteria found naturally in your gut.
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What are probiotics used for?
Yogurts, soya milk and deitary supplements.
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What do they help?
To keep your digestive system healthy and your immune system strong.
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What are prebiotics?
These promote growth of good bacteria and are carbohydrates that we cannot digest.
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Where do they occur?
Leeks, onions and oats.
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What do plant stanol esters reduce?
Cholesterol.
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What are plant stanol esters?
Plant stanol esters are chemicals that can lower blood cholesterol and reduce the risk of heart diseases.
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Where do they occur?
In plant of very small quantities.
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What do manufacturers do with plant stanol esters?
They add the to spreads and dairy products.
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If people are worried about their cholesterol, what may they buy?
Some spreads and diary products.
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Give 4 things that show functional foods have been scientifically proven.
1. Is the study reported in journals? 2. Was it written by a qualified person? 3. Was the sample of people asked a reliable source? 4. Have there been other studies where the same results have occurred?
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Card 2

Front

Give 3 ways in which fossils can be formed.

Back

1. Gradual replacement by minerals. 2. Forms casts and impressions. 3. Forms preservation in places where no decay happens.

Card 3

Front

Describe how gradual replacement by minerals occurs.

Back

Preview of the front of card 3

Card 4

Front

Describe how casts and impressions are formed.

Back

Preview of the front of card 4

Card 5

Front

Describe how preservations are formed when no decay happens.

Back

Preview of the front of card 5
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