SNAB TOPIC 4- Biodiversity and Natural resources

How do zoos/seed banks preserve genetic diversity?

ZOOS

•Animals are selected to prevent inbreeding between closely related individuals

•A STUD BOOK is used to select individuals for mating and record all breeding events

•There is an exchange of animals and gametes between zoos.

SEED BANKS

•Seed banks collect seeds from various (endangered/rare/important) plant species.

•The seeds are cleaned, dried and frozen, which preserves genetic material.

•Seed banks actively participate in the exchange/distribution of seeds to be grown or conserved somewhere else.

•Research is made behind the correct collection storage and germination of the seeds to enhance conservation efforts.

4.1 Know that over time the variety of life has become extensive but is now being threatened by human activity.

Variety has become extensive but is now being threatened by human activity such as deforestation.

4.2 i) Understand the terms biodiversity and endemism.

Biodiversity - the variety of living organisms

Endemism - the state of a species being unique to a geographical location

4.2 ii) (PAR T A) Know how biodiversity can be measured within a habitat using species richness and within a species using genetic diversity by calculating the heterozygosity index

Species richness: the number of different species in a habitat

Species evenness: Abundance of each species

4.2 ii) (PART B) Know how biodiversity can be measured within a species using genetic diversity by calculating the heterozygosity index

Genetic diversity:

The number of alleles in a gene pool

Heterozygosity index

(Number of heterozygotes)÷(Total number of individuals in the population)

4.2 iii) Understand how biodiversity can be compared in different habitats using a formula to calculate an index of diversity

4.3 Understand the concept of niche and be able to discuss examples of adaptation of organisms to their environment

Niche: The role a species takes within a community

Species which share the same niche compete with each other, leaving the better adapted species behind. (natural selection)

Adaptations

Behavioural, improving chance of survival/reproduction e.g. mating calls

Anatomical, external or internal e.g. Camouflage, e.g. long loops of Henle in kidneys of desert mammals, allows them to retain water

Physiological - processes e.g. regulation of blood flow through the skin e.g. toxin/antifreeze proteins

4.4 Understand how natural selection can lead to adaptation and evolution.

1) Random mutations in a population

2) Variation of phenotypes/Genotypes

3) Environmental change poses as a selection pressure

4) Some individuals are advantaged due to their phenotype

5) This allows them to survive and reproduce, passing advantageous alleles to offspring

6) Over time, frequency of alleles in a population changes

4.5 i) Understand how the Hardy-Weinberg equation can be used to see whether a change in allele frequency is occurring in a population over time.

p + q = 1

4.5 ii) Understand that reproductive isolation can lead to accumulation of different genetic information in populations, potentially leading to the formation of new species.

Reproductive isolation--> Accumulation of different alleles in two populations--> eventually speciation can occur

Speciation may be allopatric (geographic isolation) or sympatric (non-geographic isolation e.g. behavioural, anatomical, temporal, gametic)

4.6 i) Understand that classification is a means of organising the variety of life based on relationships between organisms using differences and similarities in phenotypes and in genotypes, and is built around the species concept.

Organisms are studied based on their similarities/differences

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

4.6 ii) Understand the process and importance of critical evaluation of new data by the scientific community, which leads to new taxonomic groupings, including the three domains of life based on molecular phylogeny, which are Bacteria, Archaea, Eukaryota.

New data about organisms were collected, analysed and peer reviewed.

New discoveries such as genotype determination lead to better clarification.

Eventually, phylogeny (evolutionary history) and molecular phylogeny (DNA/protein history comparison) proved itself as evidence supporting the case for 3 domains of life.

Prokaryota, Archaea and Eukaryota

Eukaryotes: Plants, animals fungi

Prokaryotes: bacteria, protozoa

4.7 Know the ultrastructure of plant cells

4.7 Know the ultrastructure of plant cells (cell walls)

Cell walls are the rigid outermost layer made of cellulose fibrils, stacked and held together by a matrix. Some cell walls are fortified with lignin

supports plant

4.7 Know the ultrastructure of plant cells (chloroplasts)

Thylakoid stacks (grana), stroma, matrix, double membrane, inter membrane space

4.7 Know the ultrastructure of plant cells (amyloplasts)

Membrane bound organelles consisting of starch granules

Storage of starch grains

4.7 Know the ultrastructure of plant cells (tonoplast/vacuole)

Spaces enclosed by a membrane in cytoplasm are called vacuoles. Tonoplast is the name of the membrane around the vacuole.

Maintains turgidity. They store/breakdown waste products

4.7 Know the ultrastructure of plant cells (plasmodesmata)

Cytoplasmic bridge between two adjacent plant cells

Enables transport and communication between cells.

(these are similar to gap junctions present in animal cells)

4.7 Know the ultrastructure of plant cells (pits)

Pit= depression in cell wall

Two adjacent cells (on top of each other) forms a pit pair.

Enables transport between adjacent cells

Not found in animal cells

4.7 Know the ultrastructure of plant cells (middle lamella)

Cementing material between plant cells

Made of calcium pectate and magnesium pectate.

Provides stability.

4.8 Be able to recognise the organelles in 4.7 from electron microscope (EM) images.

4.9 (PART A) Understand the structure and function of the polysaccharids starch

Starch

Starch is made of amylose & amylopectin

α-glucose units - both bonding OH groups on the ring face down

Amylose

- α 1-4 glycosidic bond

-unbranched, coiled

Amylopectin

-α 1-4 glycosidic bonds AND α 1-6 glycosidic bonds at branch point.

4.9 (PART B) Understand the structure and function of the polysaccharide cellulose, including the role of hydrogen bonds between β-glucose molecules in the formation of cellulose microfibrils.

Cellulose

Makes the cell wall

Beta glucose units- one bonding OH group on the ring faces down, the other faces up

Long, linear/unbranched chains of β-glucose, joined by β 1-4 glycosidic bonds

Microfibrils, formed when (50-80) chains are linked together by large numbers of hydrogen bonds to provide structural support.

4.10 Understand how the arrangement of cellulose microfibrils and secondary thickening in plant cell walls contributes to the physical properties of xylem vessels and sclerenchyma fibres in plant fibres that can be exploited by humans.

Plant fibres such as xylem vessels and sclerenchyma fibres are made of long tubes.

Microfibrils in the cells walls are arranged like a net. They are held together by a matrix.

Secondary thickening- adding more lignin over time as plant grows

Uses of plant fibres

Ropes or fabrics, as they are strong

CORE PRACTICAL 6:

Identify sclerenchyma fibres, phloem sieve tubes and xylem vessels and their location within stems through a light microscope.

Equipment

Plant sample

Coverslip

Mounted needles + forceps

Toluidine blue

Glycerol

(Filter paper, watch glass, coverslip)

Method

•Place the plant sample on watch glass.

•Pick out one/two vascular bundles and place on slide

•Tease vascular bundles apart with needles

•Add drop of stain, leave for a few mins

•Blot off extra stain

•Add drop of glycerol

•Examine under Low, medium and high

Observations

Xylem=long elongated tube like cells, walls thickened in spiral/ring formation. WIDER DIAMETER

Phloem sieve tube elements= also elongated, thin walls. Sieve plates visible as perforated cell walls.

Sclerenchyma - Long slender, HEAVILY STAINED. Outer edge of bundle.

Phloem- Smaller cells, more circular/rectangular than xylem. Cell walls less distinct.

4.11 Know the similarities and differences between the structures, position in the stem and function of sclerenchyma fibres, xylem vessels and phloem.

Sclerenchyma

Provides support

Long, tube like, no pits, thickened with lignin.

Xylem vessels

Provides support/transport of water & ions.

Long, tube like, with pits.

Phloem tissue

Enables translocation of organic solutes.

Sieve tube elements: Living cell, lacks nucleus, joins to form sieve tube

Companion cells: Have a nucleus/organelles so can provide energy to help sieve tube elements to transport actively.

CORE PRACTICAL 7:

Investigate plant mineral deficiencies.

Equipment

•5 plants

•Test tube rack

•Ruler

•Solution containing all minerals

•Solution containing all except magnesium ions

•Solution containing all except nitrate ions

•Solution containing all except calcium ions

•Solution containing no minerals

•Tin foil

Method

1) Half fill test tubes with each solution

2) Cover top with foil

3) Measure initial lengths of each seedling

4) Push roots of plantlet into solution, repeat for each tube

5)Wrap all tubes in foil (except for on top)

6) Place test tube rack on sunny window sill

7) Measure the length of the plants every other day, for two weeks

Control

The controls for this practical are the solution with all minerals, and the solution with no minerals.

Observations

Magnesium deficiency- stunted growth, yellowed leaves as chlorophyll cannot be made. Reddish brown tint

Nitrate deficiency- yellowed leaves and stunted growth

Calcium ions- stunted growth, soft plant lacking support as cell walls are weakened.

No minerals-Dead plant

All minerals- healthy plant, full growth

4.12 Understand the importance of water and inorganic ions (nitrate, calcium ions and magnesium ions) to plants.

Water

•Regulating temperature

•Transporting minerals

•Photosynthesis

•Maintain structural rigidity

Nitrate ions

•DNA production

•Protein production

•Chlorophyll production

Magnesium ions

•Needed for chlorophyll production

•Needed to create middle lamella

Calcium ions

•Needed to create middle lamella

•Needed to create cell walls

CORE PRACTICAL 8:

Determine the tensile strength of plant fibres.

Equipment

Stems of chosen plants

Sharp knife/scalpel

Paper towels

Clamp stands

A set of same type of weights

White tile

Method

1) Remove fibres*

2) Clamp fibre between two clamp stands

3) Add mass in middle, increase in increments

4) Note down mass required to snap fibre

5) Compare between different plants

* Soak plants if fibres are not easily obtainable

4.13 Understand the development of drug testing from historic to contemporary protocols, including William Withering's digitalis soup, double blind trials, placebo, three-phased testing.

Digitalis soup-Trial and error

Three phased testing

1) test on healthy individuals. find side effects.

2) test on large numbers of patients

3) test on thousands of patients, compare existing and new treatment.

Placebo- Inactive substances, looks like a drug but isn't. Acts as a control to compare how effective the new drug is.

Double blind study Neither patient nor doctor knows who has the placebo/drug --> No bias.

4.14 Understand the conditions required for bacterial growth.

•Source of nutrients

•Supply of oxygen for aerobic bacteria

•Optimum temperature/pH

CORE PRACTICAL 9:

Investigate the antimicrobial properties of plants, including aseptic techniques for the safe handling of bacteria.

Equipment

Pestle and mortar

Petri dish with agar seeded with E.coli

Ethanol

Sterile pipettes.

Garlic

Mint

Paper discs

Method

1) Crush garlic, add 10cm3 of alcohol. Shake for 10mins

2) Do same for mint

3)Pipette 0.1cm3 of each solution onto separate paper discs

4) Place the discs on agar

5) Close each disc, seal with tape, leave gap for oxygen

6) Leave to incubate overnight

7) Measure the radii of the clear zones of inhibition, compare with control disc

aseptic techniques:

-disinfected surfaces

-inoculating loop with

-incubation below 37 degrees C to prevent pathogens from thriving

-using flamed inoculating loops to transfer bacteria

Control

Add a disc that has 0.1cm3 of distilled water on it.

Calculation

Calculate area of zone of inhibition-->A=πr² .

Calculate mean using repeat data for each plant disc.

Conclusion

Garlic has a larger zone of inhibition, it has more antimicrobial properties.

4.15 Understand how the uses of plant fibres and starch may contribute to

sustainability, including plant-based products to replace oil-based plastics.

Plant fibres can be used for rope/fabric because they are biodegradable and easier to grow

Starch can be used instead of oil based plastics to make products such as vehicle biofuel.

This is more sustainable because they are easier to regrow.

4.16 Be able to evaluate the methods used by zoos and seed banks in the

conservation of endangered species and their genetic diversity, including

scientific research, captive breeding programmes, reintroduction programmes and education.

Protected environments:

"On site conservation", controlled/restricted areas conserves biodiversity

Zoos/botanical gardens

"Off site conservation" . Allow for captive breeding, conservation & reintroduction when possible.

Reproductive/nutritional studies can be carried out in zoo.

Seed banks

Allows conservation of species when habitat is not available and reintroduction when habitat is available.

Zoos/seed banks help educate people about the importance of wildlife/growing plants from seeds.