Paper 2 biology flashcards

describe the structure of a nucleotide

phosphate

(phosphate attached to a) sugar

(which has 1 of 4) base(s)

(bases) are A, C, G and T

Describe how non-coding parts of DNA can affect the expression of genes.

(non-coding parts) can switch genes on / off

control variables other than time, temp, conc & volume

time of day

quantity

monocultures

the cultivation or growth of a single crop or organism especially on agricultural or forest land

Suggest one reason why some people are concerned about the use of golden rice.

may harm (human) health allow may cause side effects

what do giberellins do

to increase fruit size

to promote flower production

What is the advantage of golden rice compared with non-GM rice?

golden rice has improved nutritional value

label it

A- cornea

B- iris

C- cilary muscles

D - lense

E - suspensory ligaments

F - retina

G - optic nerve

H - sclera

cornea

(transparent layer at the front that allows light to be focused onto the retina

iris

(muscle which controls the size of the pupil to adapt to bright or dim lighting)

cillary muscles and suspensory ligaments

(hold lense in place ans control it’s shape)

retina

(light sensitive layer at the back of the eye which, stimulates retinal cells, sending impulses to the brain)

optic nerve

(connects eye and brain so impulses r carried to the brain for an image to b visualised)

sclera

(tough outer layer of the eye which protects it’s internal structures

how does the iris alter to bright lighting

CIRCULAR MUSCLES CONTRCAT

RADIAL MUSCLES RELAX

makes pupil smaller, avoids retinal damage

how does the iris alter to dim lighting

CIRCULAR MUSCLES relax

RADIAL MUSCLES contract

makes pupil larger so more light enters

how does the eye focus on a nearby object

1. ciliary muscles contract
2. (so ciliary muscles have a) smaller diameter
3. (so) suspensory ligaments loosen / slacken
4. (so) lens thickens or lens becomes more curved / rounded
5. (thicker) lens is more convergent
6. light rays / image focused on retina

how does the eye focus on a fraway object

cillary muscles relx

suspendory ligaments tightern

lense becomes thingner and light rays are refracted weakly

The medium ground finch and the small ground finch both feed on seeds

The size of seeds eaten by each bird depends on the depth of the bird’s beak

The range of beak depth of medium ground finches on Isabela Island is different from the range on Daphne Island. Explain what might have caused this difference.

1. colonisers of Isabela have a range of beak depths
2. due to mutation
3. large range of size seeds on Isabella
4. more competition for seeds on Isabela
5. birds with larger beaks get enough food to survive and reproduce
6. survivors pass on beneficial alleles to offspring

how to correct long sighted ness

convex / converging lens

light rays bent / refracted (inwards) more

light rays focused on retina

marathon runners often drink sports drink during a race explain why

to replace water ions an salt, that is lost in sweat

why might estimates of graph values with the x axis being time be inaccurate

the readings are too far apart

The results show that when the ice-cold water was drunk, the temperature near the brain decreased.

Explain why the temperature near the brain decreased.

blood is cooled at the mouth, this cooled blood then flows to the brain

How does the thermoregulatory centre send information to sweat glands in the skin?

via neurones

name organ a

liver

If the eye then focuses on the words in a book, changes would occur in the eye.

The light rays would be refracted more by the lens.

How does the lens refract the light more?

by becoming thicker

describe two improvements the students should make to their investigation

• keep temperature the same (for all dishes)

• use equal numbers of seedlings (in each dish)

• measure light intensity

A gene is a length of DNA. What type of substance does a gene code for?

protein

Describe how structure Q causes the change in the size of the pupil from A to B.

**muscle** contraction

Give two possible effects of an increase in global air temperature on living organisms.

• (some) plants grow faster / higher yield

• loss of habitat

• migration or change in distribution

• extinction

Explain why more water was lost through the skin during the race. (she was running)

more energy needed

(so) more (aerobic) respiration

(so) increased breathing (rate / depth)

Light is an environmental factor that affects the growth of dandelion plants.

Give two other environmental factors that affect the growth of dandelion plants

• temperature

• water

• (soil) pH

• minerals / ions

• wind

• herbivores

One advantage of asexual reproduction for bluebells is that only one parent is needed.

Suggest two other advantages of asexual reproduction for bluebells.

• many offspring produced

• takes less time

• (more) energy efficient

• genetically identical offspring

• successful traits maintained due to offspring being genetically identical

• no transfer of gametes or seed dispersal

Explain why sexual reproduction is an advantage for bluebells.

1. genetic variation (in offspring)
2. (so) better adapted survive
3. (and) colonise new areas by seed dispersal
4. many offspring so higher probability some will survive

A large amount of untreated sewage entered the river. Many fish died.

Untreated sewage contains organic matter and bacteria.

Explain why many fish died.

bacteria decay organic matter / sewage / algae / dead plants

(by) digestion

(and) bacteria respire aerobically

(which) lowers oxygen concentration

(so) reduced energy supply causes death of fish

Suggest why IVF and embryo transfer were used rather than allowing animals 7 and 8 to mate naturally.

takes less time (to obtain results)

or more offspring at the same time

The scientists will selectively breed some of the animals shown in Figure 11.

Describe how the scientists would do this

1. find females with low fat in milk and high milk yield
2. find males whose female offspring have high milk yield and low fat in milk
3. cross the best (for both features) female with the best male
4. select the best offspring (for both features) from each generation and repeat for several generations

what is the order of the classification system Linnaeus

kingdom

phylum

class

order

family

genus

species

Due to evidence available from chemical analysis, there is now a ‘three domain system’ developed by Carl Woese. In this system, organisms are divided into:

• archaea (primitive bacteria usually living in extreme environments)

• bacteria (true bacteria)

• eukaryota (which includes protists, fungi, plants and animals).

Describe how the ancestors of modern species A may have evolved into the species B

isolation of different populations

habitat variation

genetic variation or mutation

better adapted survive

(eventually) cannot produce fertile offspring with other populations

drawbacks of selective breeding

reduces the __**gene pool**__ of the population

inbreeding; makes them prone to disease or inherited defects as the gene pool is so small

what is a gene pool

collection of different alleles in a population

what is selective breeding

selecting for certain alleles that code for the traits that we want

uses of selective breeding

• Disease resistance in food crops.

• Animals which produce more meat or milk.

• Domestic dogs with a gentle nature.

• Large or unusual flowers.

steps of genetic engineering (transfering the gene from one organism to another)

dna is cut at specific base with restrictive enzyme to create a sticky end

vector dna is cut using the same restrictive enzymes to create complementary sticky ends

ligas enzymes, join the sticky ends together to form a recombinant dna

recombinant dna is mixed up with and taken up by target cells

how do you isolate a section of dna

using enzymes

what did darwin do?

studied geology & fossils

developed the theory of evolution by natural selection

darwin’s natural selection

• Individual organisms within a particular species show a wide range of variation for a characteristic. '

• Individuals with characteristics most suited to the environment are more likely to survive to breed successfully.

• The characteristics that have enabled these individuals to survive are then passed on to the next generation.

The theory of evolution by natural selection was only gradually accepted because

• the theory challenged the idea that God made all the animals and plants that live on Earth

• there was insufficient evidence at the time the theory was published to convince many scientists • the mechanism of inheritance and variation was not known until 50 years after the theory was published.

Jean-Baptiste Lamarck’s idea

Changes that occur in an organism during its lifetime can be inherited.

We now know that in the vast majority of cases this type of inheritance cannot occur

speciation

closely related species were often separated by geographical barriers such as a wide river

how does speciation happen

over time, natural selection will favour different alleles on the two sides on each side of the geographical barrier

In the **mid-19th century,** Gregor Mendel carried out breeding experiments on plants. One of his observations was …

In the **late 19th century** he observed….

1. that the inheritance of each characteristic is determined by ‘units’ that are passed on to descendants unchanged.
2. the behaviour of chromosomes during cell division

In the early 20th century it was observed that chromosomes and Mendel’s ‘units’ behaved in __________ ways. This led to the idea that …..

1. similar
2. the ‘units’, now called genes, were located on chromosomes.

In the mid-20th century the structure of ______ was determined and the mechanism of gene function worked out.

1. DNA

what happens in meiosis

1. copies of the genetic information are made
2. the cell divides twice to form four gametes, each with a single set of chromosomes
3. all gametes are genetically different from each other

what are substances labelled ACGT

bases

describe how non coding parts of DNA can affect the expression of genes

the non coding parts can turn on /off

describe how scientists would selectively breed a type of cattle that makes **large volumes** of **low-fat milk**

1. find female with low(est) fat in milk **and** high(est) milk yield
2. find male whose female offspring have high(est) milk yield **and** low(est) fat in milk
3. cross the best (for both features) female with the best male
4. select the best offspring (for both features) from each generation and repeat for several generations

who developed the three domain system of classification

carl woese

suggest how scientists can estimate when X animal was alive by looking at the fossile

compare to other fossils of known age

two factors that may have caused the extinction of species X

* (new) predators
* new disease
* competition for food
* comp for mates
* habitat change

when using tissue culture to produced many plants from one plant why are **several groups scraped off the leaf**

so many / several plants can be produced

when using tissue culture to produced many plants from one plant why are **nutrients added to the agar jelly**

for making protein / amino acids

for making chlorophyll

for providing energy

for respiration

when using tissue culture to produced many plants from one plant why are **hormones added to the agar jelly**

so differentiation occurs

so roots / shoots develop

when using tissue culture to produced many plants from one plant why are **plant cells kept at 20*C**

so optimum / good growth

which two scientists proposed the theory of evolution by natural selection

Alfred Russel Wallace

Charles Darwin

what is a fossil

remains of an organism

from a long time ago

why is fossils for older things, harder to find

• fossils buried deep(er) so hard(er) to find

• more likely to be destroyed by geological activity / earthquakes

• oldest organisms were soft-bodied so most of the tissue decayed

pros of mass extinction

allows evolution of new species / varieties

con of mass extinction

• loss of potential, future biodiversity

what is deamination

Deamination is the removal of an amine group from a molecule.

amino acid → ammonia → urea

excess amino acids are broken down in the liver through deamination

what is the role of the kidney

filtration of blood to make urine

maintaining water ballance

why is it important to maintain water ballance

prevent bursting or shrivelling of red blood cells

what is filtered in the blood into the kidney

amino acids, glucose, water, salt, urea

what is reabsorbed back into the blood

amino acids and glucose via active transport

(some salt and water is also absorbed)

describe how a healthy kidney produces urine

kidney filters the blood

reabsorbs all the glucose

reabsorbs some ions and water

releases the rest in urea

How should the student decide where to place the quadrat?

coordinates

to achieve randomness

Using the mean from this investigation to calculate the number of daisy plants on the lawn may not be accurate.

too few quadrats,

sample may not be representative of the lawn

Suggest two improvements to the method to make the results more valid.

place (many) more quadrats

divide quadrats into more / smaller squares

estimate actual percentage cover in quadrat (instead of counting squares)

Describe:

• how microorganisms in the layers of soil help to recycle chemicals in the dead plants

• how the chemicals are used again by living plants

*in microorganisms*

• enzymes

• respiration

• production of carbon dioxide

*in plants*

• carbon dioxide (from air) taken in by leaves

• by diffusion

• via stomata

• carbon dioxide used in photosynthesis

difference between the process of meiosis and mitosis (3 marks)

1. one cell division in mitosis but two cell divisions in meiosis
2. mitosis produces genetically identical cells, but meiosis produced genetically different cells
3. mitosis produces diploid cells but meiosis produces haploid cells

similarity between mitosis and mieosis

**DNA** doubles / copies / replicates

A functional MRI (fMRI) scanner allows a person to move while the scanner makes images of the person’s brain activity.

Suggest how the fMRI scanner could help to find out more about the brain damage a person has.

• can ask people to do different tasks (while taking scan)

• to see which part of brain is active / inactive

• to compare with a person without brain damage

• to see (exactly) where the damage is

Describe how the brain receives information about light entering the eye.

1. (cells in) retina sensitive to light
2. impulse passes along (sensory) neurone
3. (along) optic nerves

why is the genotype Dd

has D because has Dupuytren’s and cannot be homozygous / DD or all the children would have Dupuytren’s

classes of organisation as determined by CARL LINEAUS

kingdom

phylum

class

order

family

genus

speicies

binomial system

genus then species

why wer new classification models proposed

developments in microscopy allowed for better examination of internal structures

improvement in understanding of biochemical processesw

what are the 3 domains

archaea → bacteria usiually living in extreme environments go here

eukarya

bacteria

which kingdoms belong in the domain eukarya

plants animals fungi protists

how are evolutionary trees created

by examining the dna of diff species and analysing how similar the sequences are

what does progesterone inhibit

FSH and LH

explain hohw photo tropism in a plant shoot helps the plant to survive

more light absorbed

increased photosynthesis

more glucose

give 1 reason why the total biomass of the daphnia in the pond is different from the total biomass of algae

* • non-digestible parts (of algae) or lost in faeces
* • not all absorbed
* • lost in urine / urea

explain how food from insects can improve human food security

less land required

(so) more space for crops (for humans)

less methane (from animals)

therefore less global warming

(therefore) less harmful effects of global warming on (human) food production

why is it more difficult to find older fossils

* fossils buried deep(er) so hard(er) to find
* older eras less researched by scientists because less to find
* allow oldest organisms were soft-bodied so there were very few fossils

advantages of mass extinction

allows evolution of new species / varieties

benefits of studying the whole human genome

• diagnosis of inherited / genetic disorder

• gene therapy or treatment of inherited disorders

• understanding (human) evolution

• diagnosis of inherited / genetic disorder

• gene therapy or treatment of inherited disorders

• understanding (human) evolutions