Biology Paper 1 Topic 1 - Cell Level Systems

What are light microscopes useful for?

Viewing whole cells or large sub cellular structures

What do the eye piece and objective lenses do?

Magnify the object

What are light microscopes useful for?

Viewing whole cells or large sub cellular structures

What do the eye piece and objective lenses do?

Magnify the object

What happens to the specimen for a light microscope?

It is placed on a glass slide, covered with a cover slip and placed on the stage of the microscope

What does a lamp provide for a light microscope?

it provides illumination

How is magnification calculated?

By multiplying the magnification of the eyepiece lens by the megnification of the objective lens

What is typical magnification and resolution?

Magnification - between 40 and 2000 times larger with a resolution of about 0.2 micrometers

How can stains be used in microscopes?

They colour whole cells and structures within cells to make them easier to see

Why are mordants sometimes used in microscopes?

They fix the stain to the structures

What are electron microscopes useful for?

Viewing sub cellular structures, such as ribosomes, mitochondrial membranes and nuclear membranes in detail

What do electron microscopes use?

A beam of electrons instead of a lamp

What happens to the specimen in electron microscopes?

It is placed inside a vacuum chamber

What is used instead of lenses?

Electromagnets

Where is the image viewed for electron microscopes?

On a TV screen

What is the typical magnification and resolution for an electron microscope?

1 to 2 million times larger with a resolution of 2 nanometres

How do you convert m to mm?

multiply by 1000

how do you convert mm to um?

multiply by 1000

how do you convert um to nm?

multiply by 1000

What sub cellular structures are common to both plant and animal cells?

The nucleus, cytoplasm, cell membrane and mitochondria

What does the nucleus do?

controls the cell and contains genetic material in the form of chromosomes

what does the cytoplasm do?

where most chemical reactions take place

what does the cell membrane do?

a barrier that controls the passage of substances into and out of the cell and contains receptor molecules

what does mitochrondria do?

contains the enzymes for cellular respiration and is the site of respiration

What else do plant cells contain that animal cells don't have?

cell wall, vacuole, chloroplasts

what does the vacuole do?

contains cell sap, which provides support

what does the cell wall do?

made from cellulose and provides structural support

what do chloroplasts do?

contain chlorophyll and are the site of photosynthesis

what are prokaryotes?

cells such as bacteria that have no nucleus- the nuclear material is free within the cytoplasm,they may contain additional DNA in the form of a plasmid

What are eukaryotes?

a cell that has a nucleus bound by a nuclear membrane

Is DNA a polymer or monomer?

Polymer

what does DNA stand for?

deoxyribonucleic acid

What are the two strands in DNA in the form of?

A double helix

Where is DNA found?

In the nucleus of a cell

What does DNA code for?

Proteins

What are enzymes?

Biological catalysts that increase the rate of chemical reactions inside organisms

What are enzymes made of?

Proteins

what happens to the amino acid chain?

it is folded to make a shape into which substrates can fit into it

What is the place called where substrates can fit?

the active site

what is the lock and key hypothesis?

the idea that enzymes are specific and only substrate molecules with the correct shape can fit into the active site

When are enzymes denatured?

When they lose their shape, the substrate no longer fits and the enzyme does not work

What is the rate of enzyme action affected by?

Temperature, PH, substrate concentration and enzyme concentration

What do high temperatures cause for enzymes?

They lose their shape and become denatured

What do low temperatures cause for enzymes?

it slows down the rate of reaction

What is the optimum temperature of human enzymes?

37 degrees Celsius as it is the normal human internal body temperature

what happens as the substrate concentration increases?

the rate of enzyme activity increases to the point where all the substrate present is being used

Where does cellular respiration happen?

Inside the cells of all plants and animals, it occurs continuously

What controls cellular respiration?

enzymes

what type of reaction is cellular respiration?

exothermic

in what form of energy does cellular respiration release?

a high energy molecule called ATP (adenosine triphosphate)

Where does aerobic respiration happen?

In almost all organisms all the time

What does anaerobic respiration in animals produce?

what does anaerobic respiration in animals produce and what is the equation?

lactic acid

glucose ———> lactic acid

glucose ---> lactic acid

when does anaerobic respiration occur?

when oxygen cannot be delivered to cells fast enough e.g. during exercise

what happens when exercise stops?

there is an oxygen debt which must be paid back to remove the lactic acid which has accumulated in the cells which is why breathing rate is so fast

what does anaerobic respiration produce in yeast?

what does anaerobic respiration produce in yeast and what is the equation?

ethanol

glucose ———> carbon dioxide + ethanol

glucose ----> carbon dioxide + ethanol

Aerobic respiration

where does it occur

is oxygen needed

where does aerobic respiration occur and does it require oxygen and is breakdown of glucose complete?

it occurs in mitochrondria, it requires oxygen, and breakdown of glucose is complete

oxygen is needed

complete breakdown of glucose

Anaerobic respiration-where does it occur?is oxygen needed?is breakdown of glucose complete?

occurs in cytoplasm, oxygen isn’t needed, incomplete breakdown of glucose

oxygen isn't needed

incomplete breakdown of glucose

what biological molecules do we take in from our diet?

What biological molecules do we take in from our diet and what are they examples of?

carbohydrates, proteins and lipids which are all polymers

all are polymers

what happens to biological molecules during digestion?

they are broken down by enzymes into smaller molecules called monomers

why do fats need to be broken down?

why do fats need to be broken down and what is this called?

they need to be broken down into small droplets to make them more digestible, it is called emulsification

it is called emulsification

What is bile responsible for in the small intestine?

emulsifying fats

Carbohydrase

What substrate does it act upon

What substrate does carbohydrase act upon and what is the name of the monomer produced?

substrate - carbohydrate

monomer produced- glucose

monomer produced - glucose

Protease

What substrate does it act upon

What substrate does protease act upon and what is the name of the monomer produced?

substrate - proteins, monomer- amino acids

monomer - amino acids

Lipase-What substrate does it act upon?What is the name of the monomer produced? Substrate- lipids (fats) Monomer - fatty acids, glycerol

What molecules are transported by the blood into the cells in the body?

glucose, amino acids, glycerol and fatty acids

What does the breakdown of proteins, carbohydrates and lipids produce?

the building blocks to synthesise the many different types of molecules that our bodes need to function

In the cells what can glucose, amino acids and glycerol be used for?

glucose - respiration

amino acids - make useful proteins

glycerol - making useful lipids

amino acids - make useful proteins

glycerol - make useful lipids

How do green plants and algae make their own food?

By photosynthesis

How do green plants and algae form glucose?

by trapping light from the sun to fix carbon dioxide with hydrogen

what is glucose used for by plants and algae?

to build larger molecules such as complex carbohydrates and proteins