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Biology Edexcel Alevel > Topic 4 > Flashcards

Topic 4 Flashcards

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1
Q

What is a species

A

Group of organisms that can interbreed to produce fertile organisms.

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2
Q

Population

A

Group of interbreeding organisms of same species found in an area (community is various population in a habitat)

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3
Q

Niche

A

The way an organism exploits it environment

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4
Q

Endemic

A

Only place organism is found

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5
Q

Adaptations (with examples)

A

Adaptations-features that enable organism to survive
—>Behavioural- changes in behaviour (mating calls)
—>Physiological-changes of internal processes in organisms (regulation of blood flow)
—>Anatomical-internal or external structure/physical changes (giraffe long neck)

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6
Q

Co-adaption process

A

When a two or more species undergo adaptions in a group

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7
Q

Natural selection

A

Process in which fitter individuals survive and pass on beneficial Allele to future generations

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8
Q

Evolution

A

Process when frequency of alleles in a gene pool (all alleles of all genes in a population) changes over time due to natural selection

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9
Q

Evolution via natural selection steps

A

1)Variety of phenotypes exist in population due to mutation
2)environmental changes occur so selection pressure changes
3)individuals with beneficial allele survive and reproduce
4)so frequency of alleles changes over time(evolution)

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10
Q

Heindy Weinberg equation

A

Conditions for equation - no mutation,Random mating,reproductive rate,large population size,gene pool size.

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11
Q

Reproductive isolation

A

If 2 populations become reproductively isolated new species formed due to accumulation of different genetic information in populations over time due to different selection pressures

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12
Q

Speciation (allopatric/sympatric)

A

Speciation-formation of species
Allopatric-in groups geographically isolated
Sympatric-isolated by other means (i.e in same area)

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13
Q

Biodiversity

A

Variety of living organisms in particular wealth of different species that exist due to evolution via natural selection

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14
Q

Taxonomy

A

Placing organism into groups based on shared features

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15
Q

Hierarchy of taxonomy

A

Kingdom
Phyla
Class
Order
Family
Genus
Species

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16
Q

What are the 5 kingdoms

A

Animalia (eukaryotes that are heterotrophs)
Plamtae (eukaryotes that are autotrophs)
Fungi (eukaryotes that are heterotrophs absorbing decaying matter)
Protoctista (eukaryotes that photosynthesise)
Procaryotae (prokaryotes, like bacteria)

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17
Q

How does scientific community evaluate data

A

Peer review
Present work at scientific conferences
Publish work

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18
Q

Genetic diversity

A

Measure of genetic variation found in species (number of Alleles in a gene pool), the higher variety of genotypes the more diverse the population.

Genetic variation could result from: meosis or random DNA mutations

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19
Q

Species richness

A

Number of species in habitat (most common Is called dominant)

20
Q

Ways of measuring biodiversity

A
21
Q

Ways of measuring genetic diversity (indirect/direct)

A

Direct method- DNA sequencing to determine bases that determine which alleles are present
Indirect method-DNA cut into fragments and separated by gel electrophoresis, different alleles identified as they produce different fragments

22
Q

How do plant build tall structures

A

-produce strong cell walls out of cellulose
-build tall columns/tubes from specialised cells
-stiffen special cell with lignin

23
Q

Structure of plant

A

Chloroplast- site of photosynthesis

Vacuole- contain cell sap and help store mineral also used for strength , surrounded by tonoplast (single membrane). Vacuole is turgid when H2O added.

Cell wall- made of cellulose, made of middle lamella holding cells together and cellulose microfibrills/microfibres

Amyloplasts- store amylopectin (starch), surrounded by double membrane

Pits- thin sections allowing communication between adjacent cells

Plasmodesmata- extension of cytoplasm between cell wall of adjacent cells involved in transport

24
Q

Cellulose

A

Chain of Beta glucose. Condensation reaction. 1,4 glycosidic bonds. Straight chain. H+ bonds between neighbouring OH groups and cellulose bundles form microfibrils, glue holding microfibrils together is composed of hemicellulose and pectins. Microfibrils provide strength/support they lay down at different angles.

25
Q

Xylem

A

Transport water/minerals up stem via transpiration stream as well as providing support. Long cylinders (hollow) with no end walls, cell wall thickened by cellulose to ease flow and stop cell collapsing.Lignified to make them waterproof and made of dead cells

26
Q

Phloem

A

Transports photosynthetic products via translocation. Made of living cells , has end walls which are sieve plates. Contain companion cells which contain all organelles, which perform metabolic functions.Use plasmodesmata to communicate

27
Q

Sclerenchyma

A

Found outside phloem, made of dead cells, heavily lignified and small lumen. Provide structural support.

28
Q

Importance of water of plants

A

-H+ bonds result in strong cohesive forces keeping water together during transport
-easily dissolves substances
-high SHC so temperature hard to change so water in plants helps them avoid rapid temperature changes
-water molecules easily stick to surfaces like xylem this is adhesions

29
Q

Turgid cell

A

Completely full

30
Q

Why are plant fibres useful

A

-Long and thin
-Strong
-Flexible
-Plant fibres can be added to other materials to form biocomposites

31
Q

What ions do plant need

A

—>Nitrate ions- make amino acids, chlorophyll. Lack can cause yellow leaves and studded growth.
—>Calcium ions- used to form calcium pectate they give glue between plant cells. Lack can cause misshapen leaves.
—>Magnesium ions-activate some enzymes and produce chlorophyll. Lack can cause yellow leaves away from veins.

32
Q

How is bacteria produced

A

Asexually via binary fission

33
Q

What’s does rate of growth depend on for bacteria

A

-nutrients
-temperature
-O2 for aerobic respiration
-no toxic waste

34
Q

Bacteria Cycle

A

-Lag phase (cells adjust to conditions)
-Exponential phase (cells divide as fast as possible in current conditions)
-Stationary phase (growth limited due to incorrect conditions)
-Death phase (Dead cells> cells growing)

35
Q

Drug testing

A

1)Pre clinical- using isolated cells and tissue culture o ashes for safety and effectiveness
2)Clinical 1- small group of healthy volunteers given dose. To confirm how drug is absorbed/digested/excreted
3)Clinical 2- small groups of patients (100-200) with disease given drug
4)Clinical 3-Large groups given drug . Some with placebo (inactive dummy) , double blind trail performed. If drug is effective then patients receiving drug show significant improvement.

36
Q

What are seeds used for

A

Protect embryo
Aid dispersal
Provide nutrition to new plant

37
Q

Structural differences between plant and animal cell

A

-plant cells have rigid cell wall animals don’t
-plant have chloroplast animal don’t
-animal cells have lysosomes and plants don’t
-both have Nucleus
-both have ER

38
Q

What is starch packaging

A

Starch granules can’t dissolve in water. So they are heated in water (gelatinisation), they swell and thicken, forming liquid which is cooled and the fabric produces can be used.

39
Q

How can enzymes mobilise stored food

A

—>Maltase/amylose- break starch into glucose which is converted into sucrose for transport to radicle/plumule
—>Protease- breaks proteins into amino acids
—>Lipase- breaks lipids in glycerol/fatty acids

40
Q

Why are using oil based plastics not sustainable

A

-burning fossil fuels increases C02 contributing to climate change
-oils resserves will run out
-plastics generate non-biodegradable waste

41
Q

Why is using plant based products good

A

Even though burning fuel from plants release CO2 plant are grown to counteract (no net change )

42
Q

What are issues with seed banks (storing seeds to conserve genetic diversity and prevent extinction )

A

-only some biodiversity stored
-some seeds can’t be stored in banks
-expensive (require power)

43
Q

What are the aims of captive breeding programs in zoos

A

-increase number of individuals in a species if numbers are low
-maintain genetic diversity in a captive population
-re-introduce animals into the wild

44
Q

What is genetic drift

A

Change of allele frequency over time by chance of allele not getting passed on

45
Q

What is genetic uniformaty

A

Genetic uniformity- individuals in a population have similar genotypes (adv in stable environment)
Can be disadvantage in unstable environment (diseases) it would be better to be genetically diverse

46
Q

What is Interbreeding depression

A

Many recessive alleles have harmful effect and offspring can be lees fit and not survive/reproduce

Biology Edexcel Alevel (8 decks)

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