T4 Biodiversity and Natural Resources

Question 1

How has biodiversity over time become threatened by human activity?

Answer 1

-human activities have threatened many species with extinction
-improved technology has led to more food so birth rate increases
-improved medicine, hygiene and health care decreases death rate
-as human population increases, there’s more demand for natural resources
-this has a harmful effect on atmosphere and climate and therefore aquatic and terrestrial ecosystems
-this negatively impacts species and habitats within them
Factors that affect biodiversity are
-habitat destruction (coral reefs, sea beds, land clearing for human needs/wants like housing and agriculture)
-over exploitation (of fish stocks, deforestation)
-hunting (wild species hunted at a faster rate than their replenishment)
-agriculture (eutrophication and pesticides kill insect and aquatic species, hedgerows being removed)
-climate change

Question 2

Define biodiversity

Answer 2

range and variety of genes, species and habitats within an ecosystem
it’s assessed at:
-the number and range of different ecosystems and habitats
-the number of individuals in each species (species evenness)
-the number of species and their relative abundance (species richness)
-the genetic variation within each species

Question 3

Explain how biodiversity can be measured within a habitat.

Answer 3

-species diversity can be measured by species richness in a habitat (no. of species in community)
species evenness + species diversity = biodiversity
-for larger areas, representative samples of the area can be used to estimate the total species number

RANDOM SAMPLING
- takes into account distribution and abundance
-use of quadrats which are placed on ground
-organisms within them are recorded
-can be used with plants
-laid randomly to avoid sampling bias
-calculate percentage cover

FOR ANIMALS
-sweeping net - catch flying insects and those that live in grass, sweep net back and forth
-pitfall traps - jars buried in ground to catch insects in ground and invertebrates
-kick-sampling - catch freshwater invertebrates. stream bed is kicked and insects are carried by stream into the net

Question 4

What is a niche habitat?

Answer 4

Niche - the {role/position} of a {species/organism} within the {ecosystem}

habitat - is the place where an organism lives while a niche is that organism’s role within that environment.

-a niche can only be occupied by one species so every species has a unique niche
-competition occurs if two species have the same niche and one will go extinct as it would be out-competed

Question 5

Explain how biodiversity can be compared
in different habitats using a formula to
calculate an index of diversity.

Answer 5

Index of diversity - measurement that describes the relationship between the number of species present and how each species contributes to the total number of organisms that are present in that community

D = N(n-1) / Σn(n-1)

Where:
n = total no. of organisms for a single species in the community
N = total no. of organisms in the community
Σ = sum of

Larger number (D) = higher diversity level
-useful for comparing species diversity in different habitats

Question 6

Give examples of behavioural,
physiological and anatomical adaptations of
organisms to suit their environment.

Answer 6

-adaptations occur because of abiotic and biotic selectors pressures
-they increase chances of survival and reproduction

Anatomical - structural features eg. horns, feathers, claws
Behavioural - courtship of defensive behaviours, migration, hibernation, distinct modes of communication
Physiological - processes inside the body, venom production, cellulose digestion

Question 7

How does natural selection lead to
adaptation and evolution?

Answer 7

1. there is variation in a population. this may be due to genetic mutations in DNA, that may be random, which introduce new alleles into a population. this means members of the population have beneficial alleles.
2. Environmental factors act as a selection pressure for the population eg. predation, disease, competition
3. Selection pressures increase the chances of those with a specific phenotype and with beneficial alleles surviving.
4. Beneficial, advantageous allele are passed on and inherited by offspring
5. Over many generations, the allele frequency changes, and a new species evolves through natural selection
6. Individuals that do not possess the advantageous alleles will most likely not survive long enough to reproduce, therefore reducing competition for resources. This will decrease the frequency of these non-advantageous alleles over time in a population

Question 8

How can reproductive isolation lead to
variation in populations and possibly the
formation of a new species?

Answer 8

-speciation can occur when populations of a species become separated from each other by geographical barriers

-the barrier could be natural like a body of water or man-made like a road

-this creates two populations of the same species who are reproductively isolated from each other, and as a result, no genetic exchange can occur between them

-if there are sufficient selection pressures acting to change the gene pools (and allele frequencies) within both populations then eventually these populations will diverge and form separate species

-Over time, the two populations may begin to differ physiologically, behaviourally and anatomically

Question 9

Describe the process of classification

Answer 9

-domains are the highest taxonomic rank
-species is the lowest taxonomic rank in the system.
-there are no overlaps between the taxa

Domain > kingdom > phylum > class > order> family > genus > species

species concept - different species with similar phenotypes and genotypes can have the same genus but they aren’t the same species, as they don’t produce fertile offspring

-advances in tech have made it easier to compare organisms genotypes and explain the evolutionary relationships between them

Question 10

describe molecular phylogeny and what it tells scientists

Answer 10

phylogeny - relies on similarities and differences of molecules (like DNA, RNA and proteins) between groups of organisms to see how closely they’re related
-the more similar the molecules, the more recent the common ancestor they share

Question 11

What are the similarities and differences
between plant and animal cells?

Answer 11

SIMILARITIES
-mitochondria, endoplasmic reticulum, ribosomes, Golgi apparatus, cytoplasm
-membrane bound nucleus

DIFFERENCES
-Animal cells are primarily round and irregular in shape, whereas plant cells typically have fixed, rectangular shapes.
-Plant cells contain chloroplasts, whereas animal cells do not.
-Plant cells have a cell wall composed of cellulose in addition to the plasma membrane, whereas animal cells only contain a thin plasma membrane.
-Animal cells are equipped with a centrosome and lysosomes, whereas plant cells are not.
-Plant cells have plastids and a large central, permanent vacuole, whereas animal cells do not.

Question 12

how would a scientist validate their research?

Answer 12

-peer review
-dedicated scientific journals
-scientific conferences

-is the paper valid?
-is the paper significant? (it has to add something to scientific knowledge)
-is the paper original?

Question 13

What are the differences in the structure of
starch and cellulose, how does this relate to
their function?

Answer 13

-starch has a branched component, called amylopectin, which has 1,6 glycosidic links, whereas cellulose is straight chain
-cellulose has only 1,4 glycosidic links
-every other glucose is inverted to form the glycosidic links in cellulose
-hydrogen bonds hold the chains together to form cellulose microfibrils
-starch is made of alpha glucose and cellulose is beta glucose

Question 14

describe how xylem structure relates to its function

Answer 14

1. lignified cell wall
   - adds strength to withstand hydrostatic pressure so vessels don’t collapse
   - impermeable to water
2. no end plates
   - allows mass flow of water and dissolved solutes
   -adhesive and cohesive forces aren’t impeded
3. no protoplasm (cells are dead when mature)
   - does not impede mass flow of water and dissolved solutes in the transpiration stream
4. pits in wall are non-lignified
   - lateral water movement
   - allows continual flow, in case of air bubbles in vessels
5. small vessel diameter
   - prevents breakage of water column
   - assists capillary action

Question 15

describe the arrangement of cellulose in microfibrils in a plant

Answer 15

• cellulose molecules are unbranched chains of β-glucose molecules joined by 1,4-glycosidic bonds.
• microfibrils are formed from 50-80 cellulose molecules.
• hydrogen bonds form between adjacent cellulose molecules between adjacent hydroxyl groups and oxygen atoms.
• large number of hydrogen bonds give microfibrils their tensile strength.

Question 16

Create a table outlining the similarities and
differences between sclerenchyma, xylem
and phloem vessels.

Question 17

Outline the importance of water and
inorganic ions to plant.

Answer 17

-absorbed through the root hairs on the root and travel up the stem in xylem vessels
-plant cells perform a variety of different functions in order to perform these functions efficiently, the plant requires water and inorganic ions (minerals)

Question 18

How could you investigate plant mineral
deficiencies ?

Question 19

Outline an experiment to determine the
tensile strength of plants.

Question 20

How has drug testing developed over time?

Question 21

What conditions are required for bacterial
growth?

Question 22

How would you investigate the
antimicrobial properties of plants?

Answer 22

• to prepare the plant extracts, plant tissue must be dried and ground finely
• this should be soaked in ethanol to extract the antimicrobial substances, after which it should be filtered
• equal sized discs cut from sterile absorbent paper should be dipped in the plant extract using sterile forceps
• leave the discs in the extract for the same amount of time to ensure that they absorb a similar amount of the plant extract
• the disc that will serve as the control will only be dipped in ethanol
• space the discs out evenly on the agar plate, before taping the lid on, inverting the plate and incubating it at 25°C
• this temperature will ensure good bacterial growth without stimulating the growth of human pathogens
• incubate for 24 to 48 hours

plant extract with the greatest zone of inhibition has the strongest antimicrobial nature

Question 23

How can plant fibres and starch be used to
contribute to sustainability?

Question 24

define endemism/ endemic species

Answer 24

when a species is native / only exists in a particular region
-more likely to be extinct due to their limited range

Question 25

How does climate change affect biodiversity?

Answer 25

-causes weather patterns to change so there’s more extreme conditions such as natural disasters -occurring too fast for species to adapt -global warming makes species move toward the poles and higher altitudes, so there’s increased competition there, which decreases biodiversity - plants can go extinct -increased ocean temperatures increase coral bleaching frequencies as organisms that keep them alive leave because of temperature stress -increased CO2 in the atmosphere dissolves in seawater so ocean is acidified. Organisms that need CaCO3 are negatively affected

Question 26

Describe genetic diversity

Answer 26

It’s the diversity of alleles and genes in the genome of species -same species don’t always have the same alleles for each same gene -populations of the same species can have genetic diversity -they live in different ranges of a habitat so have different selection pressures - this changes allele frequencies -genetic diversity allows species to adapt through selection pressures that are biotic and abiotic -it is limited in species that are small and geographically isolated -inbreeding in these species leads to a high proportion of homozygous individuals so there’s a low genetic diversity -recessive genetic diseases become more common

Question 27

Describe how zoos can conserve rare endemic species through captive breeding programmes and reintroduction programmes

Answer 27

In general: -to increase population size -to {maintain/increase} genetic diversity -protect them from {predators} Captive breeding: -inter zoo animal movement -selection of mates -use of IVF/surrogates Reintroduction: -reduce food intake to encourage hunting -select {habitat/reserves} -raise {awareness} of local population

Question 28

Why is the use of protected reserves likely to be more successful for animal conservation compared to captive breeding programmes?

Answer 28

-animals are more likely to breed in a natural environment -there are problems with releasing animals back into the wild so they’re avoided -less {stress} for the animals -{disease is less likely } -allows natural {inter specific relationships} to exist -wider gene pool and a large group of animals is needed -natural {diet} is available

Question 29

Describe the conditions used for the storage of seeds in seed banks

Answer 29

-dry and cold This {prevents} enzyme activity, prevents seed germination and seed decomposition

Question 30

Suggest advantages of selecting different seed sizes for long term storage

Answer 30

-maintains {genetic diversity/variation/size of gene pool} -greater change of having beneficial alleles -increases chance of future survival {due to higher adaptability/if environment changes} -less chance of being susceptible to a disease

Question 31

Define species

Answer 31

Individuals can interbreed to produce fertile offspring

Question 32

Describe the heterozygosity index

Answer 32

-the higher the proportion of heterozygotes in a population, the greater the genetic diversity -genetic diversity = phenotype + genotype -different alleles are responsible for phenotype variety in a species. -more different alleles for a characteristic = greater genetic diversity H = number of heterozygotes / number of individuals in population -you can find a H average at many loci -this can then be used as an estimate of genetic diversity of entire population genome

Question 33

explain the binomial system

Answer 33

Binomial - organism scientific name. Genus + species. Species can be universally identified -organisms can be placed into five kingdoms Kingdom Prokaryotae (Monera) -organisms that have prokaryotic cells -usually less than 5 μm Kingdom Protoctista -all eukaryotic -show great diversity -live in watery environments -can be unicellular or a group of similar cells eg. Protozoa have no cell wall, algae have cellulose and chloroplast Kingdom Fungi -all are eukaryotic -have a non cellulose cell wall made of chitin polysaccharide -saprotrophs - obtain energy by digesting decaying matter outside the cell from being parasites on living organisms -reproduce through spores that disperse on nearby ground -simple body form eg yeast, mushrooms, mould Kingdom Plantae -multicellular -all have cell walls composed of cellulose -possess large (and usually permanent) vacuoles that provide structural support -are able to differentiate into specialized cells to form tissues and organs -possess chloroplasts (containing chlorophyll) that enable photosynthesis (not all plant cells have chloroplasts) - autotrophs - synthesise organic molecules for energy use and building biomass from inorganic compounds Kingdom Animalia -animals are also multicellular eukaryotic organisms -can differentiate into many different specialised cell types that can form tissues and organs -have small temporary vacuoles (for example, lysosomes) -have no cell walls -heterotrophs, as they have a wide range of feeding mechanisms

Question 34

describe the critical evaluation of new classification data (how has classification changed over time)

Answer 34

-in the past, an organisms phenotypic characteristics were used, which was limited and led to wrong conclusions -advancement in genome sequencing and immunology allows for further research into species evolutionary relationships -this led to reclassification of some organisms and changes to classification system structure -three domain classification system which was based off new information from RNA molecular analysis -this led to prokaryotes being divide into two separate groups

Question 35

how is water and inorganic ions taken into a plant?

Answer 35

absorbed through the root hairs on the root and travel up the stem in xylem vessels

Question 36

why is water important to a plant?

Answer 36

-important component required for photosynthesis -provides a transport medium for minerals -maintains turgidity in plant cells though pressure in cell vacuoles -regulates temperature - to ensure that enzymes can function at their optimum rate

Question 37

why are magnesium ions important to a plant?

Answer 37

-important requirement for the production of chlorophyll -this provides the green colour of stems and leaves and is essential for photosynthesis

Question 38

why are calcium ions important to a plant?

Answer 38

-these form important cell wall components -plants require calcium ions for proper growth

Question 39

why are magnesium ions important to a plant?

Answer 39

-important requirement for the production of chlorophyll -this provides the green color of stems and leaves and is essential for photosynthesis

Question 40

describe adhesive and cohesive forces in the xylem

Answer 40

cohesion = hydrogen bonds between water molecules adhesion = hydrogen bonds between water molecules and cell wall

Question 41

define capillary action

Answer 41

- the spontaneous flow of a liquid into a narrow tube or porous material. - helps bring water up into the roots - can only "pull" water up a small distance, after which it cannot overcome gravity. - to get water up to all the branches and leaves, the forces of adhesion and cohesion go to work in the plant's xylem to move water to the furthest leaf

Question 42

describe the features of sclerenchyma

Answer 42

- sclerenchyma fibres are not involved in transport of substances - they provide support - they consist of bundles of dead cells - form long, hollow tubes - they do have end walls present - lignification of cell walls occur - do not have pits like xylem vessels - have more cellulose in their walls compared to other plant cells

Question 43

describe the features of phloem tissue

Answer 43

- bulk is made up of sieve tube elements (main conducting cells) and companion cells -another example of phloem is parenchyma for storage and strengthening fibres

Question 44

describe function of phloem

Answer 44

translocation - bidirectional transport of organic compounds, particularly sucrose, from sources to sinks

Question 45

how does the structure of sieve tube elements in phloem relate to their function?

Answer 45

1. sieve plates with sieve pores - allows continuous movement of organic compounds 2. cellulose cell wall - strengthens cell wall to withstand hydrostatic pressures that move the sap within 3. no nucleus, vacuole, ribosomes in mature cells (some ER and mitochondria present) - maximizes translocation space 4. thin cytoplasm - reduces friction to facilitate sap movement they line up end to end to form a continuous tube

Question 46

how does the structure of companion cells in phloem relate to their function?

Answer 46

1. nucleus and other organelles present - provides metabolic support to sieve tube elements - helps with loading and unloading sap 2. transport proteins in their plasma membrane - moves sap in and out of sieve tube elements 3. lots of mitochondria - provides ATP for sap active transport in and out of companion cells 4. plasmodesmata (channels in cell wall) - links to sieve tube elements - allows organic compounds to move from companion cells into sieve tube elements -

Question 47

describe the transpiration stream

Answer 47

1. water vapour diffuses out through stoma down a diffusion gradient 2. water evaporates from cell surfaces lining the substomatal cavity 3. water replaced by means of capillary action within cell walls 4. water is drawn out xylem 5. a continuous column of water is drawn up the xylem

Question 48

describe factors affecting rate of transpiration

Answer 48

1. Stomatal Density = The number and size of stomata. The number of stomata present on a leaf surface affects the amount of water vapour that can be lost. Leaves with more stomata will lose more water vapour than those with fewer stomata. 2. Leaf Area - Surface area to volume ratio; the more surface area exposed to the air, the more water vapour will be lost through transpiration. -Plants with more surface area exposed to the air generally have higher transpiration rates than those with less exposed surface area. Similarly, plants with thinner leaves will lose water more rapidly than those with thicker leaves. 3.Light intensity - higher light intensity levels will generally result in greater transpiration rates. This is because plants open their stomata in response to light, allowing water vapour to escape from the leaves. 4. Wind - generates more water loss because they lead to higher evaporation rates. 5. Humidity - low humidity means the plant needs to retain more water and typically develops leaves with a lesser surface area, thicker cuticles

Question 49

describe how water's thermal properties are important to a plant

Answer 49

- water cools and warms slowly due to a high specific heat capacity - this helps plants avoid rapid internal temperature changes as a result of the environment

Question 50

how is water's solvent properties important to a plant

Answer 50

- dissolved substances can be transported in xylem and phloem - sugar synthesis from photosynthesis can be transported around the plant

Question 51

describe the process of translocation

Answer 51

1. active transport moves sucrose from a companion cell into the sieve tube elements, reducing the water potential inside. 2. osmosis moves water into the phloem, which increases the hydrostatic pressure. The pressure is higher nearer the source cell and lower at the sink cell end. 3. solutes move down the pressure gradient, moving into the sink cells where they are converted into the molecules. 4. as the solutes are removed, the water potential near the sink end increases, causing osmosis to move water out of the phloem in order to maintain hydrostatic pressure gradient between the source and sink.

Question 52

describe the symptoms a plant experience with a lack of nitrates

Answer 52

- the amount of chlorophyll in the leaves, so plants ability to photosynthesise and grow reduces - leaves turn yellow, with red-brown cast - stunted growth

Question 53

describe the symptoms a plant experience with a lack of magnesium

Answer 53

- plant is limited in terms of photosynthetic ability due to a lack of chlorophyll -plant growth compromised - yellowung between leaf veins -some brownish parts -stunted growth

Question 54

describe the symptoms a plant experience with a lack of calcium

Answer 54

- cell wall support reduced and it forms the middle lamella, which is weakened. - metabolism restriction because of decreased membrane permeability - stubted growth -dead, curling leaves -weakened stem