biology aqa chapter 1 questions and answers

7/25/2019 Biology AQA Chapter 1 Questions and Answers

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Biology Homework

Biology 2 Questions:

1. What is a nucleus? And in which cells is it found?

A nucleus contains the genetic material of the cell. The nucleus is a large roundish

organelle. t is !ounded !y a dou!le mem!rane which has numerous "ores. nside the

nucleus are chromosomes and a dark region called a nucleolus which makes ri!osomes.

2. What is a cell mem!rane? And in which cells is it found?

t is a mem!rane that is found on the surface of animal cells and #ust inside the cell wall

of other cells. t$s made mainly of li"ids and "roteins. %ell mem!rane regulates the

mo&ement of su!stances into and out of the cell.

'. What is a cyto"lasm? And in which cells is it found?

%yto"lasm is a #elly(like fluid that fills a cell is called cyto"lasm. t is made u" of mostly

water and salt. %yto"lasm is "resent within the cell mem!rane of all cell ty"es and

contains all organelles and cell "arts.

). What is a ri!osome? And in which cells is it found?

*i!osome is a &ery small organelle that either floats free in the cyto"lasm or is attached

to r+*. t$s made u" of "roteins and *,A. The ri!osome is the site where "roteins are

made.

-. What are mitochondria and in which cells are they found?

They ha&e a dou!le mem!rane( the inner one is folded to form structures called cristae.

nside is the matri/ which contains en0ymes in&ol&ed in res"iration. itochondrion is the

site of aero!ic res"iration where AT is "roduced.

3. What is cell wall? And in which cells is it found?

%ell wall is a rigid structure that surrounds cell in "lants/ algae and fungi. n "lants and

algae it$s made mainly of the cellulose whereas in fungi it is made u" of chitin. %ell walls

su""ort cells and "re&ent them from changing sha"e.

4. What is a chloro"last? And in which cells is it found?

%hloro"last is a small/ flattened structure found in "lants and algal cells. t$s surrounded

!y a dou!le mem!rane. %hloro"last is the site where "hotosynthesis takes "lace.

5. What is a &acuole? And in which cells is it found?

6acuole is a mem!rane( !ound organelle found in the cyto"lasm of "lant cells. t hel"s to

maintain "ressure inside the cell and kee" the cell rigid. This sto"s "lants from wilting.

7. What is flagellum? And in which cells is it found?

8lagellum is a hairlike structure that allows !acteria and s"erm to mo&e.

19.Where is the ,A in a !acteria cell found?



Bacteria do not ha&e a nucleus. They do ha&e two ty"es of ,A;

"lasmid and chromosomal. The chromosomal ,A carries most of the genetic

information. lasmid ,A forms small loo"s and carries etra information11.What is yeast? And how does it res"ire?

Although yeast is a single(celled organism/ they "ossess a cellular organi0ation similar tothat of higher organisms/ including humans. <"ecifically/ their genetic content is

contained within a nucleus. This classifies them as eukaryotic organisms. =east can

undergo aero!ic res"iration or anaero!ic res"iration. n !read(making/ the yeast starts

off res"iring aero!ically/ "roducing water and also car!on dioide to make the dough rise.

When the air runs out/ the yeast !egins to res"ire anaero!ically.

12. +"lain why fat cells are s"ecialised?

8at cell are s"ecialised to store fat. This is im"ortant so that animals can sur&i&e when

they ha&e to go "eriods without food. A fat cell is s"ecial as it can e"and u" to 1999

times its original si0e as it fills its centre with fat. A fat cell has &ery few mitochondrialea&ing lots of s"ace for fat storage.

1'. +"lain why cone cells are s"ecialised?

%one cells are sha"ed in a weird manner/ in which there is an outer segment with

s"eciali0ed "hotorece"tors/ and a sort of neuronal stem that leads towards the !ase of

the eye. There is a nucleus and mitochondria in the cell !ut the cell also has a syna"se

which normal cells do not ha&e. These cells are used to s"ecialise colours and see in

daylight.

1). +"lain why "lant root hair cells are s"ecialised?

lants a!sor! water from the soil !y osmosis. *oot hair cells are s"ecialised for this !y

ha&ing a large surface area to s"eed u" osmosis. The a!sor!ed water is trans"orted

through the roots to the rest of the "lant where it is used for different "ur"oses.

1-. +"lain why s"erm cells are s"ecialised?<"erm %ells are s"ecialised in a num!er of ways. They ha&e a tail which mo&es !y

energy generated !y many mitochondria and "ro"els the cell. The head of

the cell contains a s"ecialised lysosome called acrosome that releases en0ymes so that

the s"erm cell can "enetrate the o&um coat of the egg.

13.What is diffusion?iffusion is the "assi&e mo&ement of "articles down a concentration gradient from an

area of high concentration to an area of low concentration.

14.Which cells are ada"ted to increase diffusion? How?

>ea&es cells are thin in order to reduce the distance that gases ha&e to diffuse through.

They are !road with a s"ongy layer inside to "ro&ide a large surface area.

15.How can the rate of diffusion !e increased?

The rate of diffusion is increased when: the distance is decreased/ the surface area

is increased/ and the concentration difference concentration gradient@ is increased.



2-.Why is digestion im"ortant?igestion is im"ortant for !reaking down food into nutrients/ which the !ody uses for

energy/ growth/ and cell re"air. 8ood and drink must !e changed into smaller molecules

of nutrients !efore the !lood a!sor!s them and carries them to cells throughout the

!ody.

23.escri!e the "rocess of digestion/ !eginning at the mouth and ending at the anus?

8ood is digested in the mouth/ stomach and small intestine. igested food

is a!sor!ed into the !loodstream in the small intestine. +cess water is a!sor!ed !ack

into the !ody in the large intestine. Any undigested food "asses out of the anus

as faeces.

24.What is meant !y the term s"eciation?

Cnce two grou"s of one s"ecies are isolated different mutations occur in each grou". f

the en&ironments differ/ different ada"tations are fa&oured !y natural selection. This

leads to different characteristics e&ol&ing in each grou" as time "asses. +&entually thegrou"s !ecome so different that if they come together again they are una!le to

inter!reed and are now se"arate s"ecies.

25.How do "o"ulations !ecome isolated?

The cause of isolation can !e gradual/ like when mountains or deserts form/ or continents

s"lit a"art. t can also !e Euick/ such as organisms !eing !lown to different "laces !y a

storm or tsunami tidal wa&es@.

27.Why can they no longer inter!reed?

6ariations and mutations that occur in one grou" are not necessarily found in the othergrou". The longer the grou"s are isolated/ the more different they are. They e&entually

!ecome different s"ecies. oreo&er/ if there is a change in the en&ironment of one grou"

it does not necessarily occur in the en&ironment of the other. <o they will e&ol&e and

ada"t differently.

'9.What are fossils?

8ossils are the "reser&ed remains of "lants or animals. 8or such remains to !e

considered fossils/ scientists ha&e decided they ha&e to !e o&er 19/999 years old. Thereare two main ty"es of fossils/ !ody fossils and trace fossils. Body fossils are the

"reser&ed remains of a "lant or animalFs !ody. Trace fossils are the remains of theacti&ity of an animal/ such as "reser&ed track ways/ foot"rints/ fossili0ed egg shells/ andnests.

'1. <tate four ways in which they are formed?

'2.Why is it difficult to find e&idence of early life forms?

Cne difficulty in identifying the earliest e&idence of life is that most of the rocks from this

"eriod ha&e !een destroyed !y erosion and "late tectonics.



''.What can we learn from fossils?By studying the fossil record we can tell how long life has eisted on +arth/ and how

different "lants and animals are related to each other.').How many s"ecies are estimated to ha&e eisted?

ore than 77 "ercent of all s"ecies/ amounting to o&er fi&e !illion s"ecies that

e&er li&ed on +arth are estimated to !e etinct. +stimates on the num!er of +arthFs

current s"ecies range from 19 million to 1) million/ of which a!out 1.2 million ha&e !een

documented and o&er 53 "ercent ha&e not yet !een descri!ed.'-.What is etinction?

+tinction of a "articular animal or "lant s"ecies occurs when there are no more

indi&iduals of that s"ecies ali&e anywhere in the world ( the s"ecies has died out.'3. <tate three ways as to why it is caused?

Three ways that s"ecies can !ecome etinct are through: ra"id changes to the

en&ironment such as the climate@/ new diseases/ new com"etitors.

'4.i&e two detailed suggestions as to why life forms in the "ast may ha&e died out?

<ome animals such as the dodo are etinct !ecause of the indirect acti&ity of humans.These islands were uninha!ited/ and the dodo had no natural "redators. Then auritius

were colonised !y the utch in 13'5. odos were hunted for food and easy to catch/

!ecause they were not afraid of "eo"le. Howe&er/ it was new com"etitors !rought to the

islands/ such as "igs/ cats and rats/ which ate the dodosF eggs and young that were

finally res"onsi!le for the etinction of the dodo.Another reason why some life forms may ha&e died out is through isolation. f the

"ockets of ha!itat where that animal can li&e are too small/ the "o"ulations in any one

"lace will !e tiny. This makes them &ery fragile !ecause they can easily !e wi"ed out !y

disease/ "redators/ a natural disaster etc. Also/ isolated "o"ulation "ockets !ecome

in!red resulting in a far greater occurrence of still!irth and deformed young that do not

sur&i&e.'5.escri!e why each of these factors affects the distri!ution of organisms: tem"erature/

nutrients/ light/ water/ oygen/ %C2.

'7.What is a Euadrat?Quadrat is often used in sam"ling "lants. t marks off an eact area so that the "lants in

that area can !e identified and counted.)9.What are line transects?

>ine transects are used when you wish to illustrate a "articular gradient or linear "attern

along which communities of "lants and/ or animals change. They "ro&ide a good way of

!eing a!le to clearly &isualise the changes taking "lace along the line. e"ending on how

detailed the line transect is/ they can usually !e accom"lished fairly Euickly.

)1.What is "hotosynthesis?

reen "lants a!sor! light energy using chloro"hyll in their lea&es. They use it to react

car!on dioide with water to make a sugar called glucose. The glucose is used in

res"iration/ or con&erted into starch and stored. Cygen is "roduced as a !y("roduct.

This "rocess is called "hotosynthesis.

)2.What is the word eEuation for "hotosynthesis?%ar!on dioide G water G light energy@ → glucose G oygen

)'.What is the sym!ol eEuation for "hotosynthesis?



3%C2 G 3H2C (((((( %3H12C3 G 3C2

)).How is light energy a!sor!ed and what is it used to com!ine?>ight is a!sor!ed !y the leaf$s chloro"lasts. <ome of the light energy is carried to the

chloro"hyll to form high energy electrons. The light energy is used to s"lit water

molecules. The !reaku" of water releases oygen/ electrons and "rotons.

)-.How can we ensure "hotosynthesis has taken "lace? i&e a ste" !y ste" guide of thee"eriment.

)3.Why does the leaf !eing thin aid diffusion?

The lea&es !eing thin aid diffusion !ecause it is a shorter distance for car!on dioide to

diffuse into the leaf cells.)4.Why does the u""er surface !eing green aid "hotosynthesis?

The u""er surface of the lea&es contain chloro"hyll which a!sor!s sunlight in order to

transfer energy into chemicals.)5.Why does the stomata hel" diffusion on the under surface of a leaf?

The stomata can o"en to allow diffusion of car!on dioide into the leaf from the

atmos"here/ and the diffusion of oygen and water &a"our out of the leaf.

)7.Why does a large surface area hel" with "hotosynthesis?A larger surface area means that there would !e more chloro"hyll "resent in the lea&es.

This would mean more light energy could !e a!sor!ed and more car!on dioide can

diffuse in meaning there is a higher rate of "hotosynthesis

-9.What is the function of the leaf &ein?6eins "ro&ide su""ort for the leaf and trans"ort !oth water and minerals &ia ylem@ and

food energy &ia "hloem@ through the leaf and on to the rest of the "lant.-1.What does the "lant use glucose for? <tate four main things.

lucose can !e used as a storage molecule in the form of starch. lucose could also !e

used to "roduce cellulose which strengthens the cell wall and it can also !e used to

"roduce "roteins such as chloro"hyll and en0ymes.

-2.-'.-).What is meant !y hydro"onics?

Hydro"onics is the "rocess of growing "lants in sand/ gra&el/ or liEuids/ with added

nutrients !ut without soil.

--.What are the ad&antages of an artificial en&ironment?

Artificial grass is dura!le/ so it can last "articularly in areas of hea&y usage/ like

walkways. nstalling artificial grass means you will ha&e a dura!le surface. =ou



only need to carry out light maintenance once the grass is installed. This/ of

course/ generates you sa&ings on time and u"(kee" costs/ and is "articularly

useful if maintenance isnFt "ossi!le or "ractical. Because you wonFt need to mow

or water the grass/ or e&en a""ly fertilisers or "esticides it is en&ironmentally

friendly. Another ad&antage is that you donFt need to water artificial grass this is

ideal where water is scarce.

-3.How could gardeners encourage "lant growth in artificial conditions? <tate at least fi&e

factors.( <electi&e weed killers kill some "lants !ut not others. This can !e useful for

getting rid of dandelions in a lawn without killing the grass/ or getting rid of

thistles in a field without killing the wheat "lants. This also sto"s the weed for

com"eting for the same nutrients as the "lants you want.( *ooting "owder makes stem cuttings Euickly de&elo" roots. *ooting "owder

contains growth hormones.

( The use of artificial light allows "hotosynthesis to continue !eyond daylight hours.

Bright lights also "ro&ide a higher(than(normal light intensity.

( The use of additional car!on dioide released into the atmos"here inside the

greenhouse also allows "hotosynthesis to continue at an increased rate.-4.What is meant !y a limiting factor?

Three factors can limit the s"eed of "hotosynthesis: light intensity/ car!on dioide

concentration and tem"erature. Without enough light/ a "lant cannot "hotosynthesise

&ery Euickly/ e&en if there is "lenty of water and car!on dioide.

-5.uring the day is there a net gain of oygen or car!on dioide to the en&ironment?The rate of "hotosynthesis is higher than the rate of res"iration therefore there is a net

gain for the en&ironment.-7. At night do "lants "hotosynthesise? Why?

lants don$t "hotosynthesise during the night as there is no sunlight which means that

there is a limiting factor.

39. At duskIdawn is the com"ensation "oint. What does this mean?The com"ensation "oint is the amount of light intensity on the light cur&e where the rate

of "hotosynthesis eactly matches the rate of res"iration.31.escri!e what you would see on a gra"h demonstrating light intensity.

32.escri!e what you would see on a gra"h demonstrating tem"erature.

3'.escri!e what you would see on a gra"h demonstrating car!on dioide le&els.



3).How would you test whether %C2 is needed for "hotosynthesis?

We take a "otted "lant ha&ing long and narrow lea&es and "lace it in a com"letely dark

"lace for a!out three days to destarch its lea&es.

2. Take a glass !ottle ha&ing a wide mouth and "ut some "otassium hydroide solution

JCH solutionK in it. This "otassium hydroide solution is to a!sor! the car!on dioide

gas from the air "resent in the glass !ottle so that no car!on dioide is left in the air

inside the glass !ottle@.

'. Take a ru!!er cork which fits tightly into the mouth of the glass !ottle and cut it into

two hal&es.

). ut a destarched leaf of the "otted "lant while it is still attached to the "lant@/ in(

!etween the two hal&es of the cut cork and then fit the cork in the mouth of the glass

!ottle. The u""er half of the leaf should remain outside the glass !ottle and only the

lower half of the leaf should: !e inside the glass !ottle.

-. The "otted "lant with its one destarched leaf half inside the glass !ottle containing

"otassium hydroide solution@ is ke"t in sunlight for ' to ) days. uring this "eriod/ the

u""er half of the leaf which is outside the glass !ottle@ gets car!on dioide from the air!ut the lower half of the leaf which is inside the glass !ottle@ does not get any car!on

dioide. This is !ecause all the car!on dioide of the air "resent in the glass !ottle has

!een a!sor!ed !y "otassium hydroide solution. And no fresh air can come into the

closed glass !ottle.

3. luck the leaf from the "lant and take it out from the glass !ottle. *emo&e the green

coloured chloro"hyll from the leaf !y !oiling it in alcohol. n this way/ we get a

decolourised leaf.

4. Wash the decolourised leaf with water to remo&e any chloro"hyll which may !e

sticking to it.

5. our iodine solution o&er the colourless leaf and o!ser&e the change in colour of the

leaf.

7. We will find that the lower half "art of the leaf which was inside the glass !ottle

ha&ing no car!on dioide around it@/ does not turn !lue(!lack on adding iodine solution

showing that no starch is "resent in this lower half of the leaf. 8rom this o!ser&ation we

conclude that the "hotosynthesis to make starch in the leaf does not take "lace without

car!on dioide.



19. The u""er half "art of the leaf which was outside the glass !ottle/ ha&ing car!on

dioide around it@ turns !lue(!lack on adding iodine solution showing that starch is

"resent in this u""er half of the leaf. 8rom this o!ser&ation we conclude that

"hotosynthesis to make starch@ takes "lace in the "resence of car!on dioide. n other

words/ car!on dioide is necessary for the "rocess of "hotosynthesis to take "lace.

3-.How would you test whether oygen is "roduced during "hotosynthesis?

f you want to show water as a factor of "hotosynthesis !y doing a test like a!o&e/ and

then you need to remo&e water from the chosen "lant lea&es. Howe&er/ once you remo&e

all the water from a "lant/ it$ll dry off and die Euickly. This means you cannot design a

test to e"eriment the necessity of water for "hotosynthesis. As the "lants die without

water/ we ha&e to conclude that "hotosynthesis too sto"s without water which

means water is also an essential factor of "hotosynthesis.

33.How would you test whether chloro"hyll is needed for "hotosynthesis?

1. We take a "otted "lant like croton whose lea&es are "artly green and "artly white. The

green "art of the leaf has chloro"hyll !ut the white "art of the leaf does not ha&echloro"hyll.

2. lace this "lant in a com"letely dark "lace for a!out three days to destarch its lea&es.

'. Take out the "otted "lant from the dark "lace and kee" it in !right sunshine for three

to four days.

). luck the &ariegated leaf from the "lant/ !oil it in water for a few minutes and then

remo&e its green colour Fchloro"hyllF !y !oiling it in alcohol. The green "arts of the leaf

get decolourised. <o/ we get decolourised leaf.

-. Wash the decolourised leaf with hot water to soften it and remo&e any chloro"hyll

which may !e sticking to it.

3. our iodine solution o&er the colourless leaf and o!ser&e the change in colour of the

leaf.

4. We will find that the outer "art of leaf that was originally white without chloro"hyll@

does not turn !lue(!lack on adding iodine solution showing that no starch is "resent in

this outer "art of the leaf. 8rom this o!ser&ation we conclude that the "hotosynthesis to

make starch does not take "lace without chloro"hyll.

5. The inner "art of leaf which was originally green contained chloro"hyll@ turns !lue(

!lack on adding iodine solution showing that starch is "resent in this inner "art of the

leaf. 8rom this o!ser&ation we conclude that the "hotosynthesis to make starch takes

"lace in the "resence of chloro"hyll. n other words/ chloro"hyll is necessary for the

"rocess of "hotosynthesis to take "lace.

34.How would you test whether light is needed for "hotosynthesis?

Take the "otted "lant and kee" it in a dark "lace for 2(' days so that the lea&es get

destarched.



2. %o&er a "art of one of its lea&es with the stri" of !lack "a"er. ake sure that you

co&er !oth the sides of the leaf.

'. ,ow "lace this "lant in sunlight for 'L) hours.

). luck the selected co&ered leaf and remo&e the !lack "a"er co&ering it.

-. lace this leaf in the !eaker containing water and !oil it for a!out 19 minutes.

3. Take out the leaf and now !oil it in alcohol/ using the water !ath/ for 19 minutes. This

remo&es the chloro"hyll.

4. Take out the leaf and wash it under running water.

5. lace this leaf in the etri dish and "ut a few dro"s of iodine solution on it. ,ow

o!ser&e the change in colour.

35.What are "roteins made u" of?roteins are made u" of smaller !uilding !locks called amino acids/ #oined together in

chains. <ome "roteins are #ust a few amino acids long/ while others are made u" of

se&eral thousands. These chains of amino acids fold u" in com"le ways/ gi&ing each

"rotein a uniEue ' sha"e.37.What do the different arrangement of amino acids form?

rimary structure is the seEuence of amino acids in the "oly"e"tide chain.The "oly"e"tide chain doesn$t remain flat and straight. Hydrogen !onds form !etween

the amino acids in the chain. This makes it automatically coil into an al"ha heli or fold

into a !eta "leated sheet( this is a secondary structure.

The coiled or folded chain of amino acids is often coiled and folded further. ore !ondsform !etween different "arts of the "oly"e"tide chain/ including hydrogen and ionic

!onds. 8or "roteins/ the tertiary structure forms their final ' structure49.<tate three things "roteins can !e used for a"art from !eing en0ymes?

roteins are used to form hormones/ trans"ort molecules such as haemoglo!in and !e

used as storage.

41.What is an en0yme?A su!stance "roduced !y a li&ing organism which acts as a catalyst to !ring a!out a

s"ecific !iochemical reaction.42.How are en0ymes "roduced?

+n0ymes are a ty"e of "rotein/ and like other "roteins/ they are made !y the translation

of the genetic code into a "articular seEuence of amino acids !y ri!osomes. After theen0yme is created as a chain of amino acids/ it folds into a "articular sha"e and often

!inds to other com"ounds/ known as cofactors/ !efore it !ecomes fully functional.4'.How would you identify an en0yme?

=ou can differentiate an en0yme from any normal cell !y the fact that it has an acti&e

site.4).What are su!strates?

<u!strates are the su!stances acted on !y an en0yme.4-.When su!strates reach the en0yme "rotein what ha""ens?



54.Which en0ymes are used in !iological detergents and why?Biological detergents and washing "owders use li"ases and "roteases to !reak

down fat and "rotein molecules from food stains that ha&e remained on clothing.

The fatty acids/ glycerol and amino acids that are "roduced are remo&ed in

the water during the washing "rocess.55.What is isomerise?

somerases are a general class of en0ymes which con&ert a molecule from one isomer to

another.

57.Why do !a!y foods need to !e "re(digested?Ba!ies donFt ha&e the "roteases to digest !a!y food/ so they are "re "rocessed with

"roteases to !reak the food down enough for a !a!y to a!sor! the nutrients79.Why is yeast used in food "roduction?

Through the "rocess of fermentation/ yeast con&erts sugars into car!on dioide and

alcohol. These two !y("roducts make yeast an etremely useful tool in food "roduction.

%ar!on dioide is what gi&es alcoholic !e&erages such as !eer and cham"agne their

characteristic !u!!les and is also res"onsi!le for rising !read.

71. n industry en0ymes are used to !ring a!out reactions at normal "H and tem"erature

that would otherwise reEuire e"ensi&e and demanding eEui"ment. Howe&er/ manyen0ymes are denatured at high tem"eratures and are difficult to "roduce.

72.Why are resin !eads used to sol&e this "ro!lem?

7'.What is res"iration?A "rocess in li&ing organisms in&ol&ing the "roduction of energy/ ty"ically with the intake

of oygen and the release of car!on dioide.7).Why is it needed?

*es"iration is the only way of creating AT energy@ and oygen for our !ody.7-.What are mitochondria? What do they ena!le?

itochondrion is the site of aero!ic res"iration where AT is "roduced.73.What is the word eEuation for aero!ic res"iration?

lucose G oygen (((

car!on dioide G water [email protected] are the !enefits of eercise on the heart?

+ercise lowers the chances of you getting dia!etes/ coronary heart disease/ heart failure

and stroke.75.What are the !enefits of eercise on the lungs?

The "rimary function of the lungs is to deli&er oygen to and remo&e car!on dioide from

the !ody. *egular eercise hel"s the "ulmonary system work more efficiently and

ena!les the lungs to take in more oygen. +&en "eo"le who suffer from chronic lung

"ro!lems can !enefit from regular "hysical acti&ity. +ercise strengthens the lim!

muscles and im"ro&es endurance/ which reduces the !reathlessness associated with

chronic lung conditions.

77.What are glycogen stores con&erted into during eercise?The muscles store glucose as glycogen. This can then !e con&erted !ack to glucose for

use during eercise.



199. What is "roduced the faster aero!ic res"iration takes "lace?uring hard eercise/ anaero!ic res"iration takes "lace as well as aero!ic res"iration. n

anaero!ic res"iration/ the waste "roduct/ lactic acid/ !uilds u" in the muscles causing "ain

and tiredness.

191. s aero!ic res"iration a long or short "rocess?>ong.

192. What is the difference !etween aero!ic res"iration and anaero!ic res"iration?Anaero!ic res"iration does not need oygen for it to ha""en whereas aero!ic res"iration

reEuires oygen. Anaero!ic res"iration releases much less energy "er glucose molecule

than aero!ic res"iration does.19'. What is meant !y the term oygen de!t?

A tem"orary oygen shortage in the !ody tissues arising from eercise.19). Why is less energy released?

uch less energy is released during anaero!ic res"iration than during aero!ic res"iration.

This is !ecause the !reakdown of glucose is incom"lete. Anaero!ic res"iration "roduces

an oygen de!t.19-. What is meant !y the term genetics?

The genetic "ro"erties or features of an organism/ characteristic193. What is meant !y the term fertilisation?The action or "rocess of fertili0ing an egg or a female animal or "lant/ in&ol&ing the

fusion of male and female gametes to form a 0ygote.194. What is the main structure in the nucleus of cells?

The main structures making u" the nucleus are the nuclear en&elo"e/ a dou!le

mem!rane that encloses the entire organelle.195. What are they found in?

197. What is meant !y di"loid?i"loid is a cell or organism that has "aired chromosomes/ one from each "arent. n

humans/ cells other than human se cells/ are di"loid and ha&e 2' "airs of

chromosomes.119. What is meant !y ha"loid?

Ha"loid is the term used when a cell has half the usual num!er of chromosomes.111. What are genes?

A gene is the !asic "hysical and functional unit of heredity. enes/ which are made u" of

,A/ act as instructions to make molecules called "roteins.112. What is ,A?

eoyri!onucleic acid is a molecule that carries most of the genetic instructions used in

the de&elo"ment/ functioning and re"roduction of all known li&ing organisms and many

&iruses.11'. What are alleles?

An allele is a &ariant form of a gene. <ome genes ha&e a &ariety of different forms/ which

are located at the same "osition/ or genetic locus/ on a chromosome. Humans are called

di"loid organisms !ecause they ha&e two alleles at each genetic locus/ with one allele

inherited from each "arent.11). What is a genoty"e?

A genoty"e is an indi&idualFs collection of genes. The term also can refer to the two

alleles inherited for a "articular gene. The genoty"e is e"ressed when the information

encoded in the genesF ,A is used to make "rotein and *,A molecules.

11-. What is a "henoty"e?henoty"e is the "hysical a""earance resulting from the inherited information.

113. What is meant !y the term homo0ygous?When an indi&idual has two of the same allele/ whether dominant or recessi&e/ they are

homo0ygous. Hetero0ygous means ha&ing one each of two different alleles.



114. What is meant !y the term hetero0ygous?A di"loid organism is hetero0ygous at a gene locus when its cells contain two different

alleles of a gene.115. f an allele is dominant what does it mean?

A dominant allele always shows/ e&en if the indi&idual only has one co"y of the allele.117. When does a recessi&e allele show u"?

A recessi&e allele only shows if the indi&idual has two co"ies of the recessi&e allele.129. Who was eorge endel and what did he do?

regor endel is credited as the founder of the science of genetics. He identified many of

the rules of heredity. These rules determine how traits are "assed through generations of

li&ing things. endel saw that li&ing things "ass traits to the net generation !y

something which remains unchanged in successi&e generations of an organism ; we now

call this Osomething$ genes. regor also reali0ed that traits could ski" a generation ;

seemingly lost traits could a""ear again in another generation ; he called

these recessive traits. He identified recessi&e and dominant traits which "ass from

"arents to offs"ring. He also esta!lished/ momentously/ that traits "ass from "arents to

their offs"ring in a mathematically "redicta!le way.

121. What is meant !y monohy!rid inheritance?

onohy!rid inheritance is the inheritance of a single characteristic. The different forms

of the characteristic are usually controlled !y different alleles of the same gene.122. raw a ta!le of inheritance using the alleles T for tall and t for short?

12'. Why must chromosomes make co"ies of themsel&es !efore di&ision?

n order to ensure that when the cell di&ides/ each daughter cell recei&es an identical

co"y of the "arent cellFs genetic material.12). What is this called?

itosis

12-. How does this ha""en in terms of ,A?

itosis itself consists of fi&e acti&e ste"s/ or "hases: "ro"hase/ "rometa"hase/meta"hase/ ana"hase/ and telo"hase. Before a cell can enter the acti&e "hases ofmitosis/ howe&er/ it must go through a "eriod known as inter"hase/ during which itgrows and "roduces the &arious "roteins necessary for di&ision. Then/ at a critical "ointduring inter"hase called the < "hase@/ the cell du"licates its chromosomes and ensures

its systems are ready for cell di&ision. f all conditions are ideal/ the cell is now ready tomo&e into the first "hase of mitosis.

ro"hase is the first "hase of mitosis. uring this "hase/ the chromosomes inside thecellFs nucleus condense and form tight structures. n fact/ the chromosomes !ecome sodense that they a""ear as cur&y/ dark lines when &iewed under a microsco"e. Because

each chromosome was du"licated during < "hase/ it now consists of two identical co"ies



called sister chromatids that are attached at a common center "oint calledthe centromere.

m"ortant changes also take "lace outside of the nucleus during "ro"hase. n "articular/two structures called centrosomes mo&e to o""osite sides of the cell during this "haseand !egin !uilding the mitotic s"indle. The mitotic s"indle "lays a critical role during the

later "hases of mitosis as it orchestrates the mo&ement of sister chromatids to o""osite"oles of the cell.

8ollowing "ro"hase/ meta"hase !egins. At the start of meta"hase/ the microtu!ulesarrange the chromosomes in a line along the eEuator of the cell/ known asthe meta"hase "late. The centrosomes/ on o""osite "oles of the cell/ then "re"are tose"arate the sister chromatids.

After meta"hase is com"lete/ the cell enters ana"hase. uring ana"hase/ themicrotu!ules attached to the kinetochores contract/ which "ulls the sister chromatids

a"art and toward o""osite "oles of the cell. At this "oint/ each chromatid is considered ase"arate chromosome.

8inally/ once ana"hase is com"lete/ the cell enters the last stage of the di&ision "rocessL telo"hase. uring telo"hase/ the newly se"arated chromosomes reach the mitotics"indle and a nuclear mem!rane forms around each set of chromosomes/ thus creating

two se"arate nuclei inside the same cell. As 8igure ) illustrates/ the cyto"lasm thendi&ides to "roduce two identical cells.

123. Where do free!ases assem!le?

124. What is mitosis and how many cells does it "roduce?itosis is a "art of the cell cycle in which chromosomes in a cell nucleus are se"arated

into two identical sets of chromosomes/ and each set ends u" in its own nucleus. t

"roduces 2 cells each with )3 chromosomes.125. What is meiosis and where does it occur? How many cells does it "roduced?eiosis is the ty"e of cell di&ision !y which gametes/ are "roduced. eiosis in&ol&es a

reduction in the amount of genetic material. t "roduces ) daughter cells.

127. What is meant !y the term differentiation?%ellular differentiation is the "rocess of a cell changing from one cell ty"e to another.

ost commonly this is a less s"eciali0ed ty"e !ecoming a more s"eciali0ed ty"e/ such as

during cell growth.

1'9. oes this ha""en in adult cells in humans?ifferentiation continues in adulthood as adult stem cells di&ide and create fully

differentiated daughter cells during tissue re"air and during normal cell turno&er.1'1. s cell di&ision in "lants restricted? Why?

any "lant cells kee" the a!ility to differentiate as they are a!le to kee" their toti"otencythroughout their life.

1'2. What are stem cells and where are they found?A stem cell is a cell that is ca"a!le of de&elo"ing into any ty"e of cell. These stem cells

ha&e !een found in tissues such as the !rain/ !one marrow/ !lood and in the em!ryo.1''. o adults ha&e stem cells? f so what are their "ro"erties?

Adult stem cells are undifferentiated cells found throughout the !ody that di&ide to

re"lenish dying cells and regenerate damaged tissues

1'). i&e four reasons for the use of stem cells in research and four reasons against.

ros:



• Adult stem cells can !e re"rogrammed and are less likely to !e re#ected when

used in trans"lants.

• +m!ryonic stem cells can grow for at least a year in some cases/ es"ecially when

esta!lished "rotocols are used. These cells can also !e used to generate more

cell ty"es.

• nduced "luri"otent stem cells hel" a&oid issues of histocom"ati!ility in

trans"lants/ and research on these cells will hel" re"rogram diseased or

damaged tissues.

%ons:

• Adult stem cells ha&e limited a!ility to differentiate from others and are

etremely hard to grow for long "eriod in culture. There is still no technology

a&aila!le that would hel" generate these cells in large Euantities.

• +m!ryonic stem cells may not !e acce"ted when used in trans"lants !ecause

there is no "rocess to generate them. They can e&en cause tumors when used

directly from undifferentiated culture "re".

• nduced "luri"otent stem cells usually ha&e no certain method of maintenanceand re"roduci!ility.

1'-. What is cystic fi!rosis?%ystic fi!rosis is an inherited disease caused !y a faulty gene. This gene controls the

mo&ement of salt and water in and out of your cells/ so the lungs and digesti&e system

!ecome clogged with mucus/ making it hard to !reathe and digest food.1'3. What is a "olydactyl?

olydactyly is an inherited condition in which a "erson has etra fingers or toes. t is

caused !y a dominant allele of a gene. This means it can !e "assed on !y #ust one

"arent if they ha&e the disorder.

1'4. What is Huntington$s disease?HuntingtonFs disease is an inherited condition that damages certain ner&e cells in the

!rain.1'5. Why is it not "ossi!le to cure genetic diseases at the moment?

enetic diseases/ such as %ystic 8i!rosis and HuntingtonFs disease/ are caused !y small

differences in the ,A that we get from each of our "arents. These differences affect

how we use a "articular gene/ and that leads to disease. <o we canFt really get rid of a

gene to cure a disease.1'7. What is "ossi!le?

enetic testing can determine whether a "erson is carrying the alleles that cause genetic

disorders. But there are limits to the testing/ and the su!#ect raises a num!er of ethical

issues.

1)9. What is meant !y genetic finger"rinting?

,A "rofiling also called ,A finger"rinting/ ,A testing/ or ,A ty"ing@ is a forensictechniEue used to identify indi&iduals !y characteristics of their ,A.

Biology ' Questions:

1. s !lood a tissue?

Blood is considered a connecti&e tissue for two !asic reasons em!ryologically/ it has thesame origin as do the other connecti&e tissue ty"es and !lood connects the !ody



systems together !ringing the needed oygen/ nutrients/ hormones and other signalling

molecules/ and remo&ing the wastes.

2. What is "lasma? What does it contain?

lasma is the largest com"onent of !lood/ making u" a!out --P of its o&erall content.

tFs mainly made of water and surrounds the !lood cells/ carrying them around the !ody.

lasma hel"s maintain !lood "ressure and regulates !ody tem"erature. t contains a

com"le mi of su!stances used !y the !ody to "erform im"ortant functions.

'. escri!e the function of red !lood cells.*ed !lood cells contain haemoglo!in is the "rotein inside red !lood cells that carries

oygen. *ed !lood cells also remo&e car!on dioide from your !ody/ trans"orting it to the

lungs for you to ehale.). escri!e the function of "hagocytes and lym"hocytes.

hagocytes are a ty"e of cell within the !ody ca"a!le of engulfing and a!sor!ing !acteria

and other small cells and "articles. >ym"hocytes are a form of small leucocyte white!lood cell@ with a single round nucleus/ occurring es"ecially in the lym"hatic system.-. escri!e the function of "latelets.

latelets are little "ieces of !lood cells. latelets heal wounds and "re&ent !leeding !y

forming !lood clots. latelets are made in your !one marrow.3. What is a "ulse?

A "ulse is the regular thro!!ing of the arteries/ caused !y the successi&e

contractions of the heart/ es"ecially as may !e felt at an artery/ as atthe wrist.4. Why do animals need a trans"ort system?

As the si0e of an organism increases/ its surface area to &olume ratio decreases. This

means it has relati&ely less surface area a&aila!le for su!stances to diffuse through/ so

the rate of diffusion may not !e fast enough to meet its cells reEuirements.

>arge multicellular organisms therefore cannot rely on diffusion alone to su""ly their cellswith su!stances such as food and oygen and to remo&e waste "roducts. >arge

multicellular organisms reEuire s"ecialised trans"ort systems.5. What are the four main cham!ers of the heart?

There are the left atria/ left &entricle/ right atria and the right &entricle.

7. How does !lood tra&el around the heart?Cygen you !reathe in from the air "asses through your lungs into your !lood

through the many ca"illaries in the lungs. Cygen(rich !lood mo&es through your

"ulmonary &eins to the left side of your heart and out of the aorta to the rest of

your !ody.19.escri!e an artery and its function.

An artery is a &essel that carries !lood away from the heart and toward other tissues andorgans. Arteries are "art of the circulatory system/ which deli&ers oygen and nutrients

to e&ery cell of the !ody.11.escri!e a &ein and its function.

6eins are the !lood &essels that carry deoygenated !lood from "arts of our !ody !ack to

the heart.

12.What are ca"illaries?

%a"illaries are the smallest of the !odyFs !lood &essels. They are only one cell thick/ and

they are the sites of the transfer of oygen and other nutrients from the !loodstream to

other tissues in the !ody they also collect car!on dioide waste materials and fluids for

return to the &eins.

1'.Why is a dou!le circulatory system more efficient than a single system?



ou!le circulation systems deli&er greater !lood flow rate to tissues around the !ody

!ecause the heart "um"s the oygenated !lood returned to it from the lungs. This is

useful !ecause when !lood "asses through the lungs its "ressure is reduced.1).What are cardiac cells?

%ardiac muscle cells are the muscle cells that make u" the cardiac muscle.1-.What is a stent?

A stent is a small mesh tu!e thatFs used to treat narrow or weak arteries13.What are the "ro!lems of !lood transfusions?

<ome infectious agents/ such as H6/ can sur&i&e in !lood and infect the "erson recei&ing

the !lood transfusion.

14.What are the ad&antages and disad&antages of: saline/ "erfleurocar!ons and artificial

haemoglo!in?

erfleurocar!ons:( 8%s are chea" and easy to manufacture in large Euantities/ can !e stored at room

tem"erature for u" to two years ( as o""osed to weeks/ ha&e no *8 ty"e and so can

!e mied safely with any !lood grou" without the need to check first.

( %linically/ "atients must !e maintained on high concentration oygen su""lementation

!oth !efore and after administration of 8% com"ounds. At a "oint the 8% "ortionloses the a!ility to transfuse oygen into tissue while still retaining some in solution.

Artificial haemoglo!in:

( Transfused !lood is currently more cost effecti&e/ !ut there are reasons to !elie&e thismay change. 8or eam"le/ the cost of !lood su!stitutes may fall as manufacturing

!ecomes refined. Hemoglo!in(!ased !lood su!stitutes may increase the odds ofdeaths and heart attacks.

15.What are the ad&antages of mechanical and !iological heart &al&es?echanical:

( The "rimary ad&antage of mechanical &al&es is that they will last a "atient$s

lifetime. echanical &al&es are "referred for "atients with life e"ectancies

!eyond 19(1- years !ecause they eliminate the mortality risk inherent in the

re"lacement of a worn out tissue &al&e.

Biological:

( The "rimary ad&antage of tissue &al&es is their lower reEuirement for

anticoagulation thera"y/ which reduces the incidence of !leeding. 8or the ma#ority

of tissue &al&e "atients/ taking an as"irin a day is sufficient anticoagulation

thera"y. any "atients with tissue &al&es/ howe&er/ do not en#oy this !enefit due

to anticoagulation reEuirements for other heart or &ascular conditions.17.What are the ad&antages and disad&antages of artificial hearts?

n cases where a "atient has se&ere heart diseaseIdamageIfailure/ a heart trans"lant is

necessary. Howe&er/ there is often a shortage of com"ati!le heart donors a&aila!le (

meaning that many "eo"le die while on the waiting list.

Artificial man(made@ hearts "ro&ide an alternati&e as they re"licate the function of the

heart. But current designs ha&e not "ro&ed to !e &ery successful in the long term/ and

are "rone to !lood clotting within them. Therefore/ artificial hearts are only used as a

short(term measure to kee" "atients ali&e until a !iological donor heart can !e found.

biology aqa chapter 1 questions and answers

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