Diversity, Variation And Classification

Question 1

What is Meiosis?

Answer 1

• A type of cell division where gametes
are made
•
• Gametes are haploid (Contain only 1of each chromosome).
> allows them to come together in
reproduction to form a diploid cell
(has a pair/2 of each chromosome)

Question 2

How can you compare meiosis and mitosis

Answer 2

Mitosis
- chromosome number remains same
- cells produced are diploid
- produced identical only
- one division/2 cells produced
- body cell formation

Meiosis
- chromosome number halved
- cells produced haploid
- cells produced not identical
- two divisions /4 cells produced
- used in gamete formation

..
They’re different as
- mitosis only involves one division (wch separates sister chromatids)
- meiosis has two divisions (wch separate homologous pairs then sister chromatids).
-
- There’s no pairing or separating of homologous chromosomes in mitosis
- and so no crossing over or independent segregation of chromosomes.
So produces genetically identical daughter cells — unlike meiosis.

Question 3

How is DNA from One Generation is Passed to the Next by Gametes

Answer 3

1) Gametes are the sperm cells in males and egg cells in females.
> join together at fertilisation to form a zygote, wch divides and develops into a new organism.

2) Normal body cells have the diploid number (2n) of chromosomes
— meaning each cell contains two of each chromosome,
one from mum and one from dad.

3) Gametes have a haploid (n) number of chromosomes - only one copy of each chromosome.

4) At fertilisation, a haploid sperm fuses with a haploid egg,
making cell with normal diploid number of chromosomes.
> Half these chromosomes are from sperm and half are from egg

During sexual reproduction, any sperm can fertilise any egg — fertilisation is random.
- Random fertilisation produces zygotes with diff combos of chromosomes to both parents.
- This mixing of genetic material in sexual reproduction increases genetic diversity in a species

(2n/n is another way to represent diploid/haploid)

Question 4

How Gametes are Formed by Meiosis, and what meiosis is

Answer 4

Meiosis is a type of cell division.
> takes place in the reproductive organs.
> Cells that divide by meiosis start diploid, but cells formed from meiosis are haploid
—
— the chromosome number halves. Without meiosis, you’d get double the number of chromosomes when gametes fuse.

1) Before meiosis, DNA unravels and replicates
> so are two copies of each chromosome/two chromatids.

2) DNA condenses to double-armed chromosomes,each made w two sister chromatids, joined by centromere.

3) Meiosis I (first division) - the chromosomes arrange themselves into homologous pairs.
4) These homologous pairs then separate, halving chromosome number.

5) Meiosis Il (2nd division) - pairs of sister chromatids wch make each chromosome separate (centromere divides).
6) Four haploid cells (gametes) that are genetically different are produced.
diagram 1

..

About Homologous Pairs..
- Humans have 46 chromosomes — 23 pairs. One in each pair came from mum and one from dad,
> e.g. two number l’s (one from mum and one from dad), two number 2’s etc.
-
- The chromosomes that make up each pair are same size and same genes
- but may have diff gene versions (alleles).
- These pairs of chromosomes are called homologous pairs

Question 5

What happens when Chromatids Cross Over in Meiosis 1

Answer 5

During meiosis 1, homologous pairs of chromosomes come together and pair up. - The chromatids twist round each other and bits of chromatids swap over.

The chromatids still contain the same genes but
now have a diff combination of alleles.
diagram 2

Question 6

In what 2 events does Meiosis allow Production of Cells that are Genetically Different

Answer 6

There are two main events during meiosis that lead to genetic variation:

1) Crossing over of chromatids
- crossing over of chromatids in meiosis I
means that each of four daughter cells formed in meiosis contains chromatids with diff alleles
-
- after crossing over, one chromosome from each homologous pair ends up in each cell
- each cell has a different chromatid, so a diff allele set, increasing genetic variation

..
2) Independent segregation of chromosomes
- Each homologous pair of chromosomes in cells is made up of one chromosome
- from mum and one from dad
-
- When homologous pairs are separated in meiosis 1, it’s random wch chromosome ends up in wch daughter cell.
- four daughter cells produced have diff combos of maternal/paternal chromosomes.
> One chromosome from each homologous pair ends up in each cell.

This is independent segregation of the chromosomes.
- Each cell has a diff chromatid and so a diff set of alleles, wch increases genetic variation in potential offspring

Question 7

Chromosome Mutations and what are they caused by

Answer 7

Chromosome Mutations
- caused by Errors in Cell Division

In humans, when meiosis works properly, all four daughter cells end up with
23 whole chromosomes
- one from each homologous pair (1 to 23), but arent homologous pairs

But can go wrong; cells produced contain
- variations in numbers of whole chromosomes
- or parts of chromosomes.
1) eg, two cells from meiosis may have 23 whole chromosomes,
- one each of 1 to 23, but the other two may have two chromosome 6’s and other, no chromosome 6.
2) This is chromosome mutation and is caused by errors during meiosis.

3) Chromosome mutations lead to inherited conditions as errors are present in gametes (hereditary cells).
- One type of chromosome mutation is called non-disjunction
— a failure of chromosomes to separate properly.
—In ppl, non-disjunction of chromosome 21 in meiosis leads to Down’s Syndrome.

Question 8

What is non disjunction in chromosome mutation and how does it lead to downs syndrome

Answer 8

Down’s syndrome is caused by one having an extra copy of chromosome 21
(or sometimes an extra copy of part of chromosome 21).
>
&raquo_space; Non-disjunction in this case is where chromosome 21 fails to separate properly
&raquo_space; in meiosis, so one cell gets an extra copy of 21 and another gets none.
>
» Non-disjunction occurs (failure of chromosomes to separate properly)

• homologous pair fails to separate.
  When gamete with extra copy fuses to another gamete at fertilisation,
• the resulting zygote will have three copies of chromosome 21.

Question 9

What are mutations and the types

Answer 9

Gene mutations involve a change in DNA base sequence of chromosomes.

The types of errors that can occur include:
- Substitution — one base is substituted with another
-> e.g. ATGCCT becomes ATTCCT.
- Deletion — one base is deleted
-> e.g. ATGCCT becomes ATCCT.
-
- Errors can also be caused by
- insertion, duplication, addition and translocation of bases.

the order of DNA bases in a gene determines order of amino acids in a particular protein.
- If a mutation occurs in a gene
- the sequence of amino acids it codes for (and the protein formed) cd be altered

Question 10

How do Not All Mutations Affect the Order of Amino Acids

Answer 10

The degenerate nature of the genetic code
- means some aas are coded for by more than one DNA triplet.
- so not all substitutions will result in a change to amino acid sequence of protein
— coding for the same aa

HOWEVER deletions will
— the deletion of a base will change number of bases present, wch will
cause a shift in all base triplets after it.

Question 11

What are Mutagenic Agents

Answer 11

Mutations occur spontaneously
- e.g. when DNA is misread during replication.

But some things cause an increase in rate of mutations
— these are called mutagenic agents.
- Ultraviolet radiation
- ionising radiation
- some chemicals
- some viruses

Question 12

What do Lots of Different Alleles Mean in terms of a High Genetic Diversity

Answer 12

Genetic diversity describes the number of alleles in a species or population,
- and natural selection increases proportion of advantageous alleles.
- It’s all abt the most well-adapted organisms getting on with some reproduction.

1) Remember, there can be diff versions of a single gene — alleles
2) Genetic diversity is number of diff alleles of genes in a species or population.
3) Genetic diversity within a population is increased by:
- Mutations in DNA - forming new alleles.
- Diff alleles being introduced into a population when individuals from another population migrate into them and reproduce. This is known as gene flow.

> A population is a group of organisms of one species living in a particular habitat.

Genetic diversity is what allows natural selection to occur

Question 13

What are Genetic Bottlenecks

Answer 13

A genetic bottleneck is an event that causes
- a big reduction in a population
- e.g. when a large number of organisms in a population die before reproducing.

This reduces the number of diff alleles in gene pool so reduces genetic diversity.
> The gene pool is the complete range of alleles in a population.

The survivors reproduce
> a larger population is created from a few individuals.

Question 14

What is The Founder Effect (a Type of Genetic Bottleneck)

Answer 14

The founder effect describes what happens
- when a few organisms from a population start a new colony
- where there are a small number of diff alleles in initial gene pool.

• frequency of each allele in new colony may be very diff to frequency
• of those alleles in original population
  —
  — eg, an allele rare in original population may be more common in new.
• may lead to a higher incidence of genetic disease.

The founder effect can occur as a result of migration, leading to geographical separation
- or if a new colony is separated from original population for another reason, such as religion.
&raquo_space; eg the amish in USA

Question 15

How does Natural Selection Increase Advantageous Alleles in a Population

Answer 15

Randomly-occurring mutations sometimes result in a new allele being formed.
- can be harmful. wch usually means the mutated allele quickly dies out.

However, some mutations can produce alleles that are beneficial to an organism
> (e.g. a protein is produced that works better than original)
> helping organism survive in certain environments.
>
> When allele codes for characteristic that increases chances of survival,
> its frequency in the population can increase.
This process is known as natural selection. Here’s how it works:

1) Not all organisms are as likely to reproduce as each other.
- There’s differential reproductive success in a population
- ones with allele that increases chance of survival are more likely to survive, reproduce and pass genes (including the beneficial allele),
- than individuals with diff alleles

2)means that a greater proportion of next generation inherits beneficial allele.
3)so they are more likely to survive, reproduce and pass their genes.

4) So the frequency of beneficial allele increases from generation to generation.
5) Over generations this leads to evolution as advantageous alleles become more common in population.

Adaptation and selection are both key factors in evolution
- the gradual change in species over time.
- Evolution has led to huge diversity of living organisms on Earth.

Question 16

How does Natural Selection Lead to Populations Becoming Better Adapted

Answer 16

Adaptations help organisms to survive in their environment.
- They can be behavioural, physiological or anatomical.

Here are some examples:
1) Behavioural adaptations
> Ways an organism acts that increase chance of survival and reproduction.
&raquo_space; eg, possums ‘play dead’ if threatened by a predator to escape attack.

2) Physiological adaptations
> Processes inside an organism’s body that increase chance of survival.
&raquo_space; eg, brown bears hibernate over winter.
- They lower rate of metabolism (all the chemical reactions taking place in their body).
- This conserves energy, so don’t need to look for food in months when scarce.

3) Anatomical adaptations
> Structural features of an organism’s body that increase chance of survival.
&raquo_space; eg. whales have a thick layer of blubber (fat) wch helps keep warm in cold sea.

Question 17

How may Different Types of Natural Selection Lead to Different Frequency Patterns

Answer 17

You might remember natural selection alters allele trequency in a population.
- stabilising and directional selection are types of natural selection that affect allele freq in diff ways..

• Antibiotic Resistance Shows Directional Selection
- Directional selection is where individuals with alleles for characteristics of an extreme type are more likely to survive/reproduce
- cd be in response to an environmental change
>
> Bacteria evolving antibiotic resistance is an example

• Human Birth Weight Shows Stabilising Selection
- Stabilising selection is where individuals with alleles for characteristics towards middle of range are more likely to survive and reproduce.
- occurs when environment isn’t changing,
- reduces range of possible characteristics.
>
> An example of stabilising selection is human birth weight.

Question 18

How does directional selection work in antibiotic resistance

Answer 18

1) Some individuals in a population
have alleles that give resistance to an antibiotic.

2) The population is exposed to antibiotic, killing bacteria without resistant allele.

3) The resistant bacteria survive and reproduce without competition,
passing on
the allele that gives antibiotic resistance to their offspring.

4) After some time, most organisms in the population will carry the antibiotic resistance allele.

Question 19

How does stabilising selection work in terms of human birth rates

Answer 19

1) Humans have a range of birth weights.
2) Very small babies are less likely to survive
— partly as they find it hard to maintain their body temperature.

3) Giving birth to large babies can be difficult, so large babies are less likely to survive too.

4) Conditions are most favourable for medium-sized babies
- so weight of human babies tends to shift towards middle of the range.

Question 20

How do you interpret data on effects of effects of selection

Answer 20

1) describe what data shows (type of natural selection, and how number show that)

2) say why (more likely to survive winter eg and reproduce)

Question 21

How Can you Investigate Effects of Antibiotics on Bacterial Growth

Answer 21

You Test the Effects of Antibiotics Using Agar Plates

1) The bacteria youll use are likely to have been grown
- in a liquid broth (mixture of distilled water, bacterial culture and nutrients).

2) Use sterile pipette to transfer bacteria from broth
- to an agar plate (petri dish with agar jelly.)
- Spread bacteria over plate using sterile plastic spreader.

3) Use sterile forceps to place paper discs soaked
- with diff antibiotics spaced apart on plate.
- Make sure you add negative control disc soaked only in sterile water.

4) Lightly tape lid on, invert, incubate plate
- at about 25 °C for 48 hours. This allows the bacteria to grow (forming ‘lawn’).
- Anywhere bacteria can’t grow can be seen as clear patch in lawn of bacteria.
&raquo_space; This is called an inhibition zone.

5) The size of an inhibition zone tells you how well an antibiotic works.
- larger the zone, the more the bacteria were inhibited from growing.

6) A similar technique can be used to test effects of antiseptics or disinfectants on microbial growth.

diagram 3 for result

Question 22

What are Aseptic Techniques to Prevent Contamination of Microbial Cultures

Answer 22

Aseptic techniques prevent contamination of cultures by unwanted microorganisms.
> important as contamination can affect growth of microorganism that you’re working with.
>
> also important to avoid contamination with disease-causing microbes that could make you ill.

When carrying out antibiotic investigation, use following aseptic techniques:
1) Regularly disinfect work surfaces to minimise contamination.
- Don’t put any utensils on work surface.
- Contaminated utensils should be placed in beaker of disinfectant.

2) Use sterile equipment and discard safely after use.
- E.g. glassware can be sterilised before and after use in an autoclave
- steams equipment at high pressure
- Pre-sterilised plastics instruments are used once, then discarded.

3) Work near Bunsen flame.
- Hot air rises, so any microbes in air shd be drawn away from culture.

4) Minimise time spent with lid off agar plate,
- reduces chance of airborne microorganisms contaminating culture.

5) Briefly flame neck of glass container of broth just after opened/just before closed — causes air to move out container, preventing unwanted organisms from falling in.

6) You shd also take steps to protect yourself,
- e.g. wash hands thoroughly before and after handling cultures.

Question 23

Phylogeny Tells Us What About the Evolutionary History of Organisms

Answer 23

Phylogeny is the study of evolutionary history of groups of organisms.
- tells us who’s related to whom and how closely related they are.
-
- All organisms have evolved from shared common ancestors (relatives).
> can be shown on a phylogenetic tree
diagram 4

This tree show relationship between members of Hominidae family (great apes and humans).
- The first branch point represents a common ancestor of all family members.
> This ancestor is now extinct.

• Orangutans were the first group to diverge (evolve to be a diff species) from this common ancestor.
• Each of following branch points represents another common ancestor
  
  • from wch a diff group diverged. Gorillas diverged next, then humans, then bonobos and chimpanzees.
• Closely related species diverged away from each other most recently.
• E.g. humans and chimpanzees are closely related, as diverged recently.
• You can see this as their branches are close together.

Question 24

How is Classification All About Grouping Together Related Organisms

Answer 24

Taxonomy is the science of classification.
> involves naming organisms and organising them into groups.
> makes it easier to identify and study them.
-
- Scientists now take into account phylogeny when classifying organisms
- and group organisms according to their evolutionary relationships.

1) There are eight levels of groups used to classity organisms.
- These groups are called taxa.
- Each group is called a taxon.

2) The groups are arranged in a hierarchy,
- with largest groups at top
- smallest groups at the bottom
- Organisms can only belong to one group at each level in hierarchy — there’s no overlap.

3) Organisms are first sorted into three large taxa called domains
— the Eukarya, Bacteria and Archaea.

4) Related organisms in a domain are then sorted to smaller groups called kingdoms, > e.g. all animals are in animal kingdom.
- domain
- kingdom
- phylum
- class
- order
- family
- genus
- species

5) As you move down hierarchy,
> more groups at each level
> but fewer organisms in each group.
The organisms in each group also become more closely related

6) in the final group - species
— the groups there contain only one type of organism (e.g. humans, dogs, E. coli).

7) Scientists constantly update classification systems
- as of discoveries abt new species and new evidence abt known organisms
- (e.g. DNA sequence data)

Question 25

Whats a species

Answer 25

A species is a group of similar organisms able to reproduce to give fertile offspring.

Question 26

How is The Binomial Naming System Used in Classification

Answer 26

1) The nomenclature (naming system) used for classification is called the binomial system - all organisms are given one internationally accepted scientific name - in Latin that has two parts. The first part of the name is the genus name (with capital letter). The second part is the species name. > E.g. using binomial system humans are Homo sapiens. > Names are written in italics (or underlined if handwritten.) The binomial system helps avoid confusion of using common names. E.g. over 100 diff plant species are raspberries and one buttercup species has over 90 common names

Question 27

What is Courtship Behaviour and how can it be Used to Help Classify Species

Answer 27

Courtship behaviour is carried out by organisms - to attract a mate of the right species. It can be simple, e.g. releasing chemicals, or complex, e.g. a series of displays. Courtship behaviour is species specific — only members of same species will do and respond to that courtship behaviour. — allows members of same species to recognise each other, — preventing interbreeding and making reproduction more successful >> (as mating with wrong species won't produce fertile offspring). Because of this specificity, courtship behaviour can be used to classify organisms. - The more closely related species are, the more similar their courtship behaviour. .. - Some examples of courtship behaviour include: 1) Fireflies give off pulses of light. The pattern of flashes is specific to each species. 2) Crickets make sounds similar to Morse code, the code being diff for diff species. 3) Male peacocks show off their colourful tails. This tail pattern is only found in peacocks. 4) Male butterflies use chemicals to attract females. Only those of the correct species respond.

Question 28

How can Advances in Techniques Clarify Evolutionary Relationships

Answer 28

New/improved technologies can result in new discoveries being made and the relationships between organis being clarified. > can lead to classification systems being updated. Technologies useful for clarifying evolutionary relationships include: 1) Genome sequencing - its where the entire base sequence of an organism's DNA can be determined. - The DNA base sequence of one organism can then be compared to another organisms', - to see how closely related they are. - Closely related species have a higher percentage of similarity in their DNA base order - - Genome sequencing has clarified the relationship between skunks and Mustelidae family (weasels and badgers). > Skunks had genome sequencing done; their DNA sequence was significantly diff to other members of that family. > reclassified into the family Mephititi. 2) Comparing amino acid sequence - Proteins are of amino acids. - The sequence of aas in a protein is coded for by base sequence in DNA. - Related organisms ha s similar DNA sequences; similar aa sequences in proteins. 3) Immunological comparisons - Similar proteins will also bind the same antibodies > Eg. if antibodies to human version of protein are added to isolated samples from some other species, > any protein that's like human version will also be recognised (bound) by that antibody.

Question 29

How have Gene Technologies Changed the Way Genetic Diversity is Assessed

Answer 29

genetic diversity is the number of different alleles in a population. 1) Early estimates of genetic diversity were made by looking - at frequency of measurable or observable characteristics in a population, - e.g. number of diff eye colours in a population and number of ppl with each eye colour. 2) Since diff alleles determine diff characteristics - a wide variety of each characteristic in a population indicates a high number of diff alleles — and so a high genetic diversity. 3) but gene technologies have now been developed that allow us to measure genetic diversity directly: • diff alleles of same gene will have slightly different DNA base sequences. - Comparing DNA base sequences of same gene in diff organisms in a population - allows scientists to find out how many alleles of that gene there are in that population. • • diff alleles will also produce slightly diff mRNA base sequences, - and may produce proteins with slightly diff aa sequences, so these can also be compared. 4) These new technologies can all be used to give more accurate estimates of genetic diversity in a population or species. - They also allow the genetic diversity of diff species to be compared more easily.

Question 30

How can Variation be Caused by Genes, the Environment, or Both

Answer 30

Variation is the differences that exists between individuals. - There's variation between species and within species. 1) Variation can be caused by genetic factors. - Diff species have diff genes, wch causes variation between species. - Individuals of same species have same genes, but diff alleles (versions of genes) — this causes variation within a species. 2) Variation in a species can also be caused by differences in environment, e.g. climate, food, lifestyle. 3) Most variation in species is caused by a combo of genetic and environmental factors. > E.g. genes determine how tall an organism can grow, > but nutrient availability affects how tall the organism actually grows.

Question 31

What are samples

Answer 31

samples are used as models for the whole population. - as sample data will be used to draw concs abt the whole population - it's important that it accurately represents the whole population - and that any patterns observed are tested to ensure they're not by chance. To ensure sample isn't biased, it shd be random. > if you were looking at plant species in a field > you cd pick random sample sites by dividing field into a grid and using a random number generator to select coordinates. > To ensure any variation observed in the sample isn't just by chance, > it's important to analyse results statistically; allows you to be more confident that results are true >> so will reflect what's going on in the whole population.

Question 32

Whats standard deviation ⭐️

Answer 32

The Standard Deviation Tells You About Variation Within a Sample - tells you how much values in a sample vary. - a measure of spread of values abt the mean. - Sometimes you'll see the mean written as, e.g. 9 +/- 3. > means that mean is 9 > the standard deviation is 3 so > most values are spread between 6 to 12. A large standard deviation means values in sample vary a lot. A small standard deviation tells you most of sample data is round the mean value, so varies little. **diagram 5** = interpret standard deviation graphs

Question 34

How can you Use Standard Deviation to Draw Error Bars

Answer 34

Standard deviations can be plotted - on a graph or chart of mean values - using error bars Error bars extend one standard deviation above and one standard deviation below the mean >> (so total length of an error bar is twice standard deviation). The longer the bar, the larger the standard deviation and more spread sample data is from mean. **diagram 6** error bars

Question 35

Whats biodiversity, habitats and communities

Answer 35

1) Biodiversity — the variety of living organisms in an area. Areas with a high biodiversity are those with lots of different species. 2) Habitat — the place where an organism lives, e.g. a rocky shore or field. 3) Community — all the populations of different species in a habitat.

Question 36

How Can Biodiversity be Considered at Different Levels

Answer 36

Biodiversity can be considered at a range of scales - from the local to the global. 1) Local biodiversity - you cd consider the variety of diff species living in a small habitat that's local to you — e.g. a pond or meadow, or back garden. — Some habitats will be more biodiverse than others. 2) Global biodiversity - you could also consider variety of species on Earth. — Recent estimates put total number of species on Earth at abt 8.7 million. — Biodiversity varies in diff parts of the world — it is greatest at the equator and decreases towards poles.

Question 37

How can Biodiversity be Measured Using an Index of Diversity

Answer 37

Species richness is a measure of the number of diff species in a community. > worked out by taking random samples of a community > and counting the number of diff species. Species richness is also a simple measure of biodiversity. - But the number of diff species in a community isn't the only thing that affects biodiversity. - The population sizes of those species do too. - Species in a community in very small numbers shdn't be treated same as those with bigger populations. .. The number of species in a community and the abundance of each species is also known as - the species diversity An index of diversity is another way of measuring biodiversity. > calculated using an equation that takes > both the number of species in a community (species richness) > and abundance of each species (population sizes) into account. >> calculate an index of diversity (d) using this formula: d = ( N(N-1) ) / ( Σ n(n-1) ) — N is tot number of organisms of all species — n is tot number of organisms in one species — Σ is sum of/added together THE HIGHER NUMBER, THE MORE DIVERSE **eg. diagram 7**

Question 38

How can Agricultural Practices Reduce Biodiversity

Answer 38

Farmers try maximise amt of foodthat they can produce from a given area of land > but many methods they use reduce biodiversity 1) Woodland clearance — done to increase area of farmland. - directly reduces number of trees and sometimes number of diff tree species. - also destroys habitats, so some species cd lose shelter and food source. - - means species will die/be forced to migrate to another suitable area, further reducing biodiversity. 2) Hedgerow removal — also done to increase farmland area by turning - many small field to fewer big fields - reduces biodiversity for same reasons as woodland clearance 3) pesticides — these are chemicals that kill organisms (pests) that feed on crops. - reduces diversity by directly killing pests. - Any species that feed on pests will lose a food source, so their numbers could decrease too. 4) Herbicides — these are chemicals that kill unwanted plants (weeds). - reduces plant diversity; cd reduce the number of organisms that feed on weeds. 5) Monoculture — when farmers have fields containing only one type of plant. - A single type of plant reduces biodiversity directly - and will support fewer organisms (e.g. as a habitat or food source), wch further reduces biodiversity.

Question 39

Whats the imporance of conservation in terms of biodiversity

Answer 39

Whilst agriculture is important, we don't want to lose too much biodiversity - So has to be a balance between agriculture and conservation. Conservationists try protect biodiversity. Some examples of conservation schemes are: • Giving legal protection to endangered species. • Creating protected areas such as SSSIs (Sites of Special Scientific Interest) • and AONBs (Areas of Outstanding Natural Beauty). > restrict further development, including agricultural development. • The Environmental Stewardship Scheme wch encourages farmers to conserve biodiversity > e.g. by replanting hedgerows and leaving margins around fields for wild flowers to grow.