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Biology Model Answers > Topic 4 > Flashcards

Topic 4 Flashcards

1
Q

Natural selection- IGNS

A

Isolation - separated
Genetic variation
Natural selection - advantageous alleles
Speciation

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2
Q

What is meany by biodiversity

A

Variety of species in an ecosystem and the variety of alleles ina gene pool

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3
Q

What is a species

A
  • group of organism
    -with similar morphology, physiology and behaviour
  • which interbreed to produce fertile offspring
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4
Q

What is a population

A
  • group of interbreeding indivuals of the same spcies
  • found in thr same area
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5
Q

What is a niche

A
  • when a species has adapted and won its habitat
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6
Q

Behavioural adaptations

A

-actions that help survival and reproduction

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7
Q

Physiological adaption

A

-features of the internal working organism that help survival and reproduction

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8
Q

Anatomical adaptations

A

-structures we can see when we observe/ dissect

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9
Q

What is co adaption

A

-when plants and its pollinator become dependent on each other over time

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10
Q

What is a gene pool

A

-consists of the alleles of all the genes present in a popualtion

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11
Q

The ability of a population to adapt to new conditions will depend on

A
  • the strength of selection pressure
    -size of gene pool
    -reproductive rate of organisms
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12
Q

What is reproductive isolation

A

-when a group of indivuals become separated from the group
-with each separate group accusations different Allele frequency’s

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13
Q

What is taxonomy

A

-placing the organisms into groups based of shared features

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14
Q

Order of taxonomic heriachy

A

Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species

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15
Q

What are the 3 domains

A
  • archaea
  • Bacteria
  • eukaryota
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16
Q

What is the differences between bacteria archaea and eukarya

A

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

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17
Q

What is specie richness

A

-the number of species present in a habitat

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18
Q

What does the term endemic mean

A

-a group of organisms that are only found in that area and no where else

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19
Q

How do plants build tall structures?

A

-they have strong cell wall made from cellulose
- they have columns and tubes from spealcised cells built in
- they stiffen some cells with ligin

20
Q

What are the properties and functions of cellulose

A
  • polysaccharide
  • made from beta glucose
  • condensation reaction
    -1,4 glycosidic bonds
  • long unbraced
  • contains microfillbs between OH groups
  • plant’s strength comes from cellulose
21
Q

Why is the cell wall so strong

A
  • pectin acts as cement and holds the cells together
    -cellulose micrfibills are arranged into a matrix of h]pectin which makes it strong
22
Q

What is a plasmodesmta

A
  • narrow fluid channels which make the cytoplasm of one cell continues with the cytoplasm of the next
23
Q

Why is the xylem a specialised cell for plant growth

A
  • forms tubes to transport water and mineral around the plant
    -also stuffers cell walls to help support the plant
24
Q

Why is the phloem a specialised cell for plant growth

A

-a long tube which transports organic solutes such as sugars amino acids around plant
-DO NOT SUPPORT PLANT

25
Q

Why is the sclerenchyma a specialised cell for plant growth

A
  • forms colours
  • stiffens the cell which provides support
26
Q

How are xylem vessel formed

A

-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

27
Q

What is the difference between prokaryotes and eukaryotes

A

Prokaryotes- no nucleus, large , DNA free , small ribosomes 70s
Eukaryotes - has nucleus, large , dna packed in nucleus , large 80 ribosomes

28
Q

How is water transported through xylem vessels

A
  • xylem vessels are fluid filled tubes
    -water moves upwards from root to shoot
29
Q

What is the transpiration stream and how does it occur

A

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

30
Q

What is the cohesion tension theory in plants

A
  • 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

31
Q

How are phloem vessels formed

A

-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

32
Q

How do phloem vessels transport substances

A

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

33
Q

What is a companion cell and where is it found

A
  • 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
34
Q

what is a turgid cell

A
  • complete full cell
  • with its cell contests pressing out on cell wall
35
Q

What is pre clinical testing

A
  • Animal and laboratory studies on isolated cells and tissue cultures
  • In order to assess the safety
  • And determine the effectiveness
36
Q

What is phase 1 of clinal trials

A

-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

37
Q

What is phase 2 in clinical trials

A
  • small group of volunteers with the disease
  • Are treated to test the drugs effectivess
38
Q

What is phase 3 of clinical trials - DBT

A

-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

39
Q

How are seeds adapted to ensure the survival of a plant

A
  • protect their embryo
    -aid dispersal
  • provide nutrition for new plant
40
Q

Why are oil based plastics/fuels not sustainable

A
  • 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
41
Q

What are captive breeding programmes and what are the positives

A
  • 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
42
Q

What is interbreeding depression

A

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

43
Q

What is in situ

A
  • on sight
  • best way to prevent genetic drift and interbreeding depression
44
Q

What is ex situ

A
  • off sight
    -can play a role in preventing genetic drift and interbreeding depression
45
Q

What are stud books

A
  • 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
46
Q

What are seed banks

A
  • 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

Biology Model Answers (8 decks)

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