Topic 4 Flashcards
Natural selection- IGNS
Isolation - separated
Genetic variation
Natural selection - advantageous alleles
Speciation
What is meany by biodiversity
Variety of species in an ecosystem and the variety of alleles ina gene pool
What is a species
- group of organism
-with similar morphology, physiology and behaviour - which interbreed to produce fertile offspring
What is a population
- group of interbreeding indivuals of the same spcies
- found in thr same area
What is a niche
- when a species has adapted and won its habitat
Behavioural adaptations
-actions that help survival and reproduction
Physiological adaption
-features of the internal working organism that help survival and reproduction
Anatomical adaptations
-structures we can see when we observe/ dissect
What is co adaption
-when plants and its pollinator become dependent on each other over time
What is a gene pool
-consists of the alleles of all the genes present in a popualtion
The ability of a population to adapt to new conditions will depend on
- the strength of selection pressure
-size of gene pool
-reproductive rate of organisms
What is reproductive isolation
-when a group of indivuals become separated from the group
-with each separate group accusations different Allele frequency’s
What is taxonomy
-placing the organisms into groups based of shared features
Order of taxonomic heriachy
Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What are the 3 domains
- archaea
- Bacteria
- eukaryota
What is the differences between bacteria archaea and eukarya
Archera - prokaryotic, circular, small subunit (70 ribosomes ), cell wall always present, has his tones and sometimes introns
Bacteria - prokaryotic , circular, 70s ribosomes , cell wall always present , no histones and never really introns
Eukarya - eukaryotic , liner chromones , large chromosomes (80) , walls is sometime time , has histones and introns always
What is specie richness
-the number of species present in a habitat
What does the term endemic mean
-a group of organisms that are only found in that area and no where else
How do plants build tall structures?
-they have strong cell wall made from cellulose
- they have columns and tubes from spealcised cells built in
- they stiffen some cells with ligin
What are the properties and functions of cellulose
- polysaccharide
- made from beta glucose
- condensation reaction
-1,4 glycosidic bonds - long unbraced
- contains microfillbs between OH groups
- plant’s strength comes from cellulose
Why is the cell wall so strong
- pectin acts as cement and holds the cells together
-cellulose micrfibills are arranged into a matrix of h]pectin which makes it strong
What is a plasmodesmta
- narrow fluid channels which make the cytoplasm of one cell continues with the cytoplasm of the next
Why is the xylem a specialised cell for plant growth
- forms tubes to transport water and mineral around the plant
-also stuffers cell walls to help support the plant
Why is the phloem a specialised cell for plant growth
-a long tube which transports organic solutes such as sugars amino acids around plant
-DO NOT SUPPORT PLANT
Why is the sclerenchyma a specialised cell for plant growth
- forms colours
- stiffens the cell which provides support
How are xylem vessel formed
-dead cells become Lined with lignin
-all cell organelles leave as they are dead
- this leaves a hollow tube with no organelles
- so water an easily flow through
-ligin makes it waterproof - so doesn’t leak out
What is the difference between prokaryotes and eukaryotes
Prokaryotes- no nucleus, large , DNA free , small ribosomes 70s
Eukaryotes - has nucleus, large , dna packed in nucleus , large 80 ribosomes
How is water transported through xylem vessels
- xylem vessels are fluid filled tubes
-water moves upwards from root to shoot
What is the transpiration stream and how does it occur
Water vapour diffuses out through the stroma down a diffusion gradient
- Water evaporates from the surfaces of cells lining the substomatal cavity
- Water is replaced by means of capillary action within the cell walls.
- Water is drawn out of the xylem
- A continuous column of water is
drawn up through xylem
- Water evaporating in this way is
known as transpiration
- The stream of water passing
through the plant is known as the transpiration stream
What is the cohesion tension theory in plants
- water is under tension as its pulled up the plants
-lignification of the xylem walls prevents them from collapsing - the water colum does not break when it’s pulled due to the cohesive forces between water molecules as a result of H bonding
Water in narrow tubes sticks together very strongly
- The movement of water through the xylem provides a mass flow system for the transport of inorganic ions
- These are absorbed into the roots and are required throughout the plant
How are phloem vessels formed
-Develops from a column of long, narrow cells in the growing stem
- Phloem cells are alive whereas xylem vessels are dead.
- The nucleus and most cell contents disintegrate during development
- Only a few organelles remaining in thin layer of cytoplasm close to the cell wall
- The end walls of each sieve tube cell contains holes that are aligned with neighbouring cell to allow transfer of material
- Perforated end walls are called sieve plates
- The section of a phloem sieve tube between sieve plates is called the sieve tube element
- The lumen is continuous through the sieve plates at each end of the
How do phloem vessels transport substances
Main substances transported are usually sucrose and amino acids
- Produced in the leaves by photosynthesis
- The fluid in the lumen moves along the sieve tube
- In some sieve tubes the fluid flows from the leaves down to the roots
- Where some sugars and amino acids are used for growth
- And sugars may be used as a source of energy or converted to polysaccharide (such as starch) and stored.
- In other cases it may move from the leaves to the buds, developing flowers, and fruits and the seeds
What is a companion cell and where is it found
- found in phloem alongside a sieve tube
-They still have have nucleus,
mitochondria, ribosomes and RER - These cells perform the metabolic
functions that maintain the sieve tube
what is a turgid cell
- complete full cell
- with its cell contests pressing out on cell wall
What is pre clinical testing
- Animal and laboratory studies on isolated cells and tissue cultures
- In order to assess the safety
- And determine the effectiveness
What is phase 1 of clinal trials
-Small group of healthy volunteers
- Are given in different dosages
- Used to determine whether or not
the drug acts as it is predicted in lab tests
What is phase 2 in clinical trials
- small group of volunteers with the disease
- Are treated to test the drugs effectivess
What is phase 3 of clinical trials - DBT
-Large group of patients are selected and divided randomly into two groups
- One group is given the compound being investigated
- The second is given a placebo
- Neither the patients nor doctors
know who has been given the drug or not
How are seeds adapted to ensure the survival of a plant
- protect their embryo
-aid dispersal - provide nutrition for new plant
Why are oil based plastics/fuels not sustainable
- Burning fossil fuels contributes to a net increase in atmospheric CO2 which contributes to climate change
- Oil reserves will eventually run out
- Plastics generate
non-biodegradable waste, creating waste disposal problems
What are captive breeding programmes and what are the positives
- take in endangered animals to breed
- they Increase the number of individuals of the species to prevent extinction
- Maintain genetic diversity within the captive population
- Reintroduce animals into the wild
What is interbreeding depression
In small populations whether in the wild or in captivity
- The likelihood of closely-related individuals mating increases
- This inbreeding causes the frequency of homozygous genotypes to rise
- Due to loss of heterozygotes
- Inbreeding results in individual
inheriting recessive alleles from both parents and the accumulation of the homozygous recessive genotypes in the offspring
- Many recessive alleles have harmful effects
- So an inbreeding depression occurs
- The offspring will therefore be less likely to survive reproduce
What is in situ
- on sight
- best way to prevent genetic drift and interbreeding depression
What is ex situ
- off sight
-can play a role in preventing genetic drift and interbreeding depression
What are stud books
- Shows the history and location of all the species
- In the places that co-operating in an overall breeding plan
- Used to ensure that genes from all of the founder members of the population are retained
- And equally represented in the subsequent generation.
- This requires that individuals that breed poorly in captivity must be encouraged to breed
- Whilst those that are particularly good must be limited
What are seed banks
- As plants are threatened by habitat destruction, climate change and over-harvesting
- Seed banks are an ex-situ form of conservation
- Small samples of seeds are taken
- They are stored easily due to their small size and ease of storage
- They are kept in dry and cool conditions
- After a month a sample is taken and germinated on agar plates
- To make sure that the seeds are still alive
- If germination rate falls below 75% then the seeds will be grown
- New seed samples will then be taken
