science light digestion reactions

what does a prism do?

splits white light into a spectrum which is called dispersion.

what is dispersion in light?

the separation of white light into its component colours.

why does dispersion occur

-the different colours of light all have different wavelengths and different frequencies.

-each colour is refracted by a different amount depending on it’s frequency.

-higher frequencies such as violet are refracted more than lower frequencies such as red.

-this spreads the colours out to produce a continuous spectrum.

what is the visible spectrum?

wavelengths of light visible to humans.

what do filters do to light

allow some colours of light through, but absorb the rest.

what makes cyan?

green + blue

what makes magenta?

red + blye

what makes yellow?

green + red

how do we see different colours?

when light hits a surface, the colours of the object is refracted and the rest absorbed. the reflected light reaches our eyes and allows us to see the object.

what do black objects do to light?

absorb all colours.

what do white objects do to light?

reflect all colours.

what happens when light is absorbed?

the object heats up.

what is the light ray travelling toward the reflecting surface called?

the incident ray.

what is the ray that has been reflected called?

reflected ray.

what is the law of reflection?

angle of incidence = angle of reflection

what is a luminous object?

an object that produces its own light.

what is an object that doesn’t produce its own light called?

non luminous.

what happens when light travels through glass?

glass transmits the light (passes through), but a small amount is absorbed.

what is a transparent object?

an object that allows light to pass through.

what happens when light travels through a translucent object? (frosted glass, tissue paper)

some light passes through and is scattered/changed direction.

what does opaque mean?

does not transmit light.

what are shadows?

opaque objects produce them by blocking light. they can be predicted as light travels in straight lines.

what is a substance present at the start of a reaction?

reactant.

what does an arrow represent instead of =?

reactants are changing into a new substance.

what is conservation of mass?

the amount of each atom stays the same but are rearranged to make a new product.

What is the name of the elements or compounds produced by a chemical reaction?

products

What has happened if it appears that some mass has been lost in a chemical reaction?

Gas had been produced and escaped.

What is a physical change?

A change in which the form or appearance changes, but no new substances are formed. They are reversible, like changes of state + dissolving.

What is a chemical reaction?

change which atoms are rearranged to make new substances. Not easily reversible or not at all. They transmit energy to surroundings

Signs of chemical reactions:

-flames or sparks
- change of temperature
- loud bang or fizzing
- different smell

What is refraction?

the bending of waves due to a change in speed

Why does the image get flipped around in your eye

Because the light from the top of the object travels diagonally to the bottom of your eye

How does the eye work?

-Light rays are reflected off an object
-They enter the eyes through the cornea.
-The light than passes through the pupil
-The light is than focused by the lens
-They continue until they hit the retina at the back
-This produces upside down image onto the retina
-Optical nerve then transmits this to the brain which sorts out information so we dont see everything upside down

What happens when the light exits the glass after refraction?

The reverse happens and it goes back to the angle it was at before

What will happen if light hits the glass block straight on?

The light will slow down but not change angle/ be refracted

Why does dispersion happen?

When white light enters glass, it slows down and bends. Because some colours of light travel mere slowly in glass than others, they bend more.

Combustion is...

Chemical reaction where a substance reacts quickly with oxygen and gives out light and heat / burning

Decomposition is ...

A chemical reaction that breaks down compounds into simpler products.

What food group is a main source of energy

Carbohydrates

What are lipids?

Fats and oils that provide energy

What food group is responsible for the growth and repair of cells and tissues?

Proteins

What are vitamins and minerals for?

Essential in small amounts to keep you healthy

What is needed in all cells and body fluids

Water

What does fibre do

Provides bulk to keep food moving through the gut.

What does not eating enough of a nutrient mean?

Unbalanced diet, can lead to a deficiency

What type of person needs a lot of carbs

Athletes/any active person who would need lots of energy

Who needs lots of protein?

Pregnant women for developing baby, body builders to build muscle and babys to help the grow

Who need lots of vitamins and minerals

Baby and pregnant women, need folic acid to develop baby

What are enzymes?

proteins that act as biological catalysts by speeding uo digestion of nutrients
Each enzyme is specific to each nutrient

What enzyme breaks down carbohydrates?

Carbohydrases

What enzyme breaks down proteins?

Proteases

What enzyme breaks down lipids?

Lipases

What do each nutrient break down into?

Carbohydrates - glucose/simple sugars
Proteins - amino acids
Lipids - fatty acids + glycerol

What is the fuction of enzymes?

To be able to break down large insoluble molecules.

enzymes have to be a specific shape so they can fit into the gap

Will more than one enzyme fit into a molocule?

no

What path does food take through the body?

-mouth
-oesophagus
-stomach
-large intestine
-small intestine
-rectum
-anus

What is the function of the stomach?

The muscular sac where food is churned with digestive juices. Acid helps kill bacteria

Where does the digestion of proteins take place?

stomach and small intestine

What is the gut bacteria?

Microorganisms that naturally live in the
intestine and help food break down

What does the liver do?

It produces bile which neutralises stomach acid and helps with fat digestion

What does the large intestine do?

Water is absorbed into bloodstream and faeces is formed from the undigested food

mouth function;

Physical digestion of food starts here as food is chewed

Oesophagus

connects mouth to stomach

Oesophagus adaptions

Muscles in the walls of the oesophagus contract and relax to push food along. The waves of contraction and relaxation are called peristalsis

What does the small intestine do?

Here digestion is completed and soluble foods are absorbed. More enzymes are produced here to complete digestion

pancreas function

produces digestive enzymes which are added to the small intestine

salivary glands function

Produces digestive juice that is added into the mouth

Name ways the small intestine is adapted for absorbtion of nutrients:

-thin wall (only one cell thick) so that small soluble food molecules can be absorbed easily
-good blood supply to transport absorbed food around body to cells
-large surface area because of villi and it is very long.

How does refraction happen?

If light travels from air to glass, it will bend because it travels more slowly in glass than it does in air. If the light travels diagonally to the glass it will hit the glass on an angle which means one side of the ray will hit the glass slightly earlier and slow down causing the light to bend.

What is villi?

-The inside of the small intestine is covered in million of villi. Villi have three features that make absorbing digested food into the bloodstream very efficient:
-The have a large surface area so that digested food is absorbed more quickly into the blood
-They have a single layer of surface cells so that digested food diffuses quickly over a short distance
-They have a very good blood supply via a capillary network to assist quick absorbtion of digested food.