1 Key Concepts In Biology

Question 1

What is an electron microscope?

Answer 1

A microscope which fires electrons through thespecimin and sensors pick up what makes it through and turns it into a visabke light image

Question 2

What is meant by an instruments resolution?

Answer 2

Resolution is how well a microscope can distinguish between 2 points, as Appleseed to them blurring into one, a higher resolution means that the image is more clear

Question 3

Why can some cell structures, such as chloroplasts only be observed properly with an electron microscope and not a light microscope?

Answer 3

Some cell structures are very small and require a very high magnification and resolution to be observed, the extent of which can only be produced by an electron microscope

Question 4

How do you calculate magnification?

Answer 4

Magnification = image size/real size

Question 5

name the parts of plant and animal cells, and describe their functions

Answer 5

Question 6

how are sperm cells adapted to their function

Answer 6

1. it has a long tail to help it swim to the ovum
2. large spiral consisting of mitocondria in the mid section to provide energy, from resperation, needed to swim
3. the acrosome is s store for enzymes needed to break down the ovums gell membrane
4. haploid nucleus

Question 7

how is an ovum(egg cell) adapted to its function?

Answer 7

1. it has a haploid nucleus
2. large amount of cytoplasm, containing nutrients for the embryo
3. after fertilisation, its membrane changes so nomore sperm can get in, ensuring the offspring has the right amount of DNA

Question 8

what is the function of a ciliated epithelial cell and how is it adapted for this function?

Answer 8

• it move substances(such as mucus)along the surface of organs(such as the trachea) in one direction(so the mucus doesnt go into the lungs and can be swallowed instead)
• ciliated epithelial cells have cilia(hair like structures)on their top surface which beat to move substances

Question 9

what are the common parts of bacteria cells and what are their functions?

Answer 9

Question 10

why are bacteria classified as prokaryotic

Answer 10

• it is a single celled organism
• they dont have a nucleus
• they lack some organells, such as mitocondria

Question 11

what is the difference between eukaryotes and prokaryotes?

Answer 11

1. eukaryotes are multicellular, prokaryotes are singlecellular
2. eukaryotic cells have a nucleus, prokaryotic cells have a single circular chromosome and plasmids
3. eukariotic cells are complex and have more organells, prokaryotic cells are missing some organelles, such as mitochondria

Question 12

what is an enzyme?

Answer 12

proteins

a biological catalyst

Question 13

what are some examples of enzymes and where are they found?

Answer 13

• amylase: breaks down starches into sugars, present in saliva and the small intestine
• lipase: breaks down fat into glyserol and fatty acids, found in the small intestine
• proteas:break down proteins into amino acids, found in the small intestine and stomach

Question 14

what are the subunits for carbohydrates, proteins and lipid?

Answer 14

sugars, amino acids , glyserol and fatty acids

Question 15

what do enzymes do?

Answer 15

catalyse the breakdown of ubstances, making reaction quicker and more efficient

and synthesis of substances back from their base units

Question 16

why is catalysis by enzymes important for life processes?

Answer 16

it allows reactions to happen much faster

Question 17

what is enzyme specifity?

Answer 17

enzymes work by locking up with substances due to a specific shape, known as the lock and key mechanism, in which only the specified substances will fit into the enzymes active sight and be able to catalyse or synthesise

Question 18

why do enzymes have their particular shape?

Answer 18

the order of amino acids which make up the enzyme controlls how it folds and when and where hydrogen bonds from to hold it in shape

Question 19

how does an enzyme become denatured?

Answer 19

if the enzyme becomes too hot, its hydrogen bonds will break and its active sight will change shape, meaning that the specific substance wil no longer fit and its activity will slow to 0

Question 20

how does temperature affect the rate of reaction of an enzyme?

Answer 20

if too cold, the rate of reaction is slow because the substrate it catalyses will move slow and bump into it less but if too hot it will become denatured, so there is an optimum temperature at which an enzyme will work best

Question 21

how does substrate concentration affect the rate of reaction of an enzyme?

Answer 21

the greater the concentration, the greater the reactin rate because there is kore chance that the substrate will come in contact with the enzyme and react, but it takes time for the reaction to happen, so there is a maximum rate as the enzyme cant react with a second bit of substrate if it is already reacting

Question 22

how odes pH affect the rate of reaction of an enzyme?

Answer 22

an enzyme has an optimum pH, which is ofetn 0, and decreases in reation rate evenly based on difference in pH above and below the optimum

Question 23

what are the 3 ways a substance can be transported in and out of a cell?

Answer 23

diffusion

osmosis

active transport

Question 24

how does active transport work?

Answer 24

transporter proteins in the membrane of a cell grab onto required substances(which are too large to fit through the permiable membrane) and using energy pull the substance into the cell, often againts the concentration gradient

Question 25

how are substances transpoted by diffusion?

Answer 25

diffusion is the overall movement of particles from a high concentration area to a low concentration area

Question 26

how is water transported by osmosis?

Answer 26

osmosis is the diffusion of water in and out of cells. water molecules move in and out of cells through tiny holes in the permiable membrane, from high concentration areas to low concentration area.