7: Genetics, Populations, Evolution and Ecosystems Flashcards

Question

What is autosomal linkage?

Answer 1

- the idea that **genes on chromosomes are 'linked'** and stay together during independent segregation in meiosis - closer 2 genes are, more closely linked, less likely to split up - preserves parental allele combinations in offspring

Answer 2

e.g. fruit flies - body colour and wing length are closely linked

Answer 3

characteristics controlled by different genes @ different loci interact to form the phenotype

Answer 4

- when the allele of one gene is able to **mask the expression** of another allele of a different gene - e.g. flower colour/ baldness & widow's peak

Answer 5

2 copies of an allele needed to mask other gene expression

Answer 6

1 allele needed to mask the other gene

Answer 7

- used to test if results of an experiment support a theory/ hypothesis - compares expected vs observed results

Answer 8

- establish null hypothesis: **there is no significant diffeent between observed and expected results** - use equation - find **critical value**: 5% chance difference due to chance

Answer 9

- if percentage/ given value < 0.05, then lower % due to chance - higher percentage certainty than 95% - there is a significant difference (between means/ observed and expected/ correlations) - reject null hypothesis - **and vise versa** | DON'T MENTION RESULTS IN CONCLUSION

Answer 10

a group of similar organisms able to reprodue and produce fertile offspring

Answer 11

a group of organisms of the same species that live in the same area at the same time and can interbreed

Answer 12

the complete range of alleles present in the population

Answer 13

how often certain alleles occur in a population

Answer 14

a mathematical model predicting/ estimating the frequence of alleles won't change from one generation to the next (uses genotypes and phenotypes in a population)

Answer 15

- population is large enough - no immigration or emmigration - no mutations - no births or deaths - no natural selection - random mating occurs- so different phenotypes occur

Answer 16

**p + q = 1** - p- frequency of dominant allele - q- frequency of recessive allele

Answer 17

**p² + 2pq + q² = 1** - p²= freq. of homozygous dominant genotype - q²= freq. of homozygous recessive genotype - 2pq= freq. of heterozygoud genotype | represents punnet sqare

Answer 18

the differences between individuals

Answer 19

variation between the **same species**

Answer 20

variation between **different** species

Answer 21

- individuals in a population show a range of phenotypes - caused by genetic and/ or environmental factors

Answer 22

- **mutations-** changes in DNA base sequence, lead to new alleles being mafe - **meiosis-** crossing over of chromatids, independent segregation of chromosomes, forms gametes - **fertelisation-** random fertelisation of gametes - **environment-** e.g. lifestyle, climate, etc. | same genes, different alleles

Answer 23

- individuals in a species with more beneficial/ adapted phenotype are more likely to survive, reproduce and pass on beneficial characteristics to offspring

Answer 24

increases allele frequency of beneficial alleles in the next generation in a gene pool

Answer 25

- caused by **prediation, disease, competition, etc.** - only genetic variation causes naturall selection - organisms face many **selection pressures** threatening their survival - different alleles and variation in species means some are better adapted to selection pressures then others

Answer 26

- occurs in **unchanging environment** - results in individuals with alleles for characteristics towards the median to be more likely to survive and reproduce - **alleles at extremes reduce chance of survival** - average allele better suited to selection pressure, more likely to survive and reproduce

Answer 27

- higher mode - less extremes - narrower, taller graph - reduced range | e.g. polar bear fur length

Answer 28

- occurs when there's **changes in an organisms environment** (e.g. competition - organisms within a species with **allele for extreme phenotype are more likely to survive and reproduce** - frequency of extreme allele increases

Answer 29

- new mode - favours exyreme - same range - graph shifts towards extreme | e.g. cheetah speed

Answer 30

- opposite of stabilising selection - occurs when **change in environment favours more than one phenotype** - organisms with allele for phenotypes at **both extremes** are more likely to survive, reproduce and pass on alleles for that phenotype

Answer 31

- 2 modes - favours extremes - mode changes - medium allele frequency decreases | e.g. beak size

Answer 32

the development of a new species from an existing species

Answer 33

- occurs when poulations of the same species become **reproductively isolated** - a change in **allele frequence** within species causes changes to their **phenotype**, so they're no longer able to **interbreed** and produce fertile offspring

Answer 34

- **geographic isolation** - when the population of a species is divided by a **physical barrier** (e.g. oceans, moutains, earthquake, etc.) - seperates individuals from main population - as no **gene flow** between populations (**allopatric speciation**)

Answer 35

- **geographical isolation** causes different selection pressures, some alleles more advantageous than others - **natural selection** occurs so **allele frequency** changes - **directional selection** occurs, changing modal allele frequency - **change in allele frequency -> change in gene pool of isolated population -> change in phenotype** - eventually, individuals change so much they can't interbreed and produce fertile offspring **(reproductive isolation)** | seperated by physical barrier

Answer 36

- natural selection - mutations - genetic drift | leads to speciation

Answer 37

- **random mutation** results in **reproductive isolation**, individuals only reproduce with individuals with the same mutation - **change in alleles, genotypes and phenotypes** causes inability to interbrees with individuals without the mutation **mutations lead to:** - **seasonal changes-** different mating/ flowering/ sexually active seasons in the year, can't breed as not sexually active at the same time - **mechanical changes-** shape, size, genitalia function prevents successful mating and breeding - **behavioural changes-** develop courtshup rituals the species doen't find attractive, preventing breeding | random mutations

Answer 38

- **no selection pressures** - can cause evolution purely due to the **random passing down of alleles to offspring** - can change/ increase allele frequency - more effective in smaller populations, could lead to **reproductive isolation/ speciation**

Answer 39

- diversity caused by speciation/ evolutionary changes - 1 population divided and evolved into seperate species

Answer 40

the place where an organism lives

Answer 41

all of the organisms of the same species living in the same place at the same time, and able to breed together

Answer 42

all of the populations of different species in the same place at the same time, interacting with each other

Answer 43

inclused all organisms living in a commnity (biotic) and non-living conditions (abiotic)

Answer 44

- the role of a species within its habitat - species of organisms living in each habitat in the ecosystem have their own unique **niche**

Answer 45

- **biotic interactions:** eats and eaten by - **abiotic interactions:** when active, temperature

Answer 46

- in an ecosystem, a niche can only be occupied by one species - may appear that a niche occupied by more than one species, however there's slight differences between them - if 2 species try and occupy the same niche, they compete until more successful one left

Answer 47

a feature a species has that increases its chance of survival and reproduction

Answer 48

- **physiological-** e.g. snake venom - **behavioural-** e.g. penguin huddling - **anatomical-** e.g. puffer fish puffing up

Answer 49

the total no. of organisms of one specied in a habitat

Answer 50

maximum stable population size of a species that their ecosystem can support - in order for population of species to survive in a habitat, there needs to be a suitable amoung of all biotic and abiotic factors that influence survival changes

Answer 51

- **population size increases** - e.g. when temperature of a mammals surroundings is ideal for metabolic reactions, they don't use up as much energy to maintain body temperature - can **use more energy for growth and reproduction** so population size increases

Answer 52

- **population size decreases** - e.g. as amount of sunlight drecreases, plants can;t photosynthesis as much, need to conserve energy - e.g. when mammals surrounded by low temperatures, they use more energy to maintain body temperature

Answer 53

- **interspecific variation-** when **different species** compete for the same resources (resources reduced if they both share it, limiting both populations so there's less energy used to reproduce, decreasing population size) | more adapted one **outcompetes other species, can't co exist** - **intraspecific variation-** when organisms of the **same species** are in competition for the same resources, can lead to **cyclical change in population size** around carrying capacity of an ecosystem | increase in population limits resources due to competition (**size exceeds carrying capacity, not enough resources, population decline, then increase, repeats**) - **prediation-** when organisms (predators) kill and eat other organisms (prey) | **interlinked**

Answer 54

- **motile organisms (moving)-** mark, release, recapture - **non-motile organisms (non-moving)-** quadrats and transects

Answer 55

- use large no. of small quadrats to increase sample size (especially if unevenly distributed) - place quadrats randomly- form grid from area, randomly select co-ordinates using random generator, place quadrat, repeat - use same 2 sides to count avoiding double counting

Answer 56

1. randomly select sampling site 2. use a fram quadrat 3. identify plant species/ count frequency 4. repeat a large no. of times 5. find mean value 6. multiply by (total area/ area of quadrat)

Answer 57

- eliminates double counting - only counts organism it touches (the pin) - horizontal bar, supported by 2 legs, 10 holes to drop large pin - **% cover= (no. hits/ total no. pins) x 100**

Answer 58

to investigate a change in distribution in an area - form of **systematic sampling** - both transects work similarly - (interruped faster but less info) - **investigate gradual changes in communities**

Answer 59

1. lay rope or measuring tape along the area (to form transect), randomly pick area 2. place quadrat along transect 3. count no. of species in quadrat 4. repeat, placing quadrat at different intervals along the tape 5. repeat at least 3 times moving transect along the land, randomly

Answer 60

1. capture organisms 2. mark in a way that's easily identifyable 3. release organisms back into same community released from, leaving them time to re-acclimatise 4. recapture organisms 5. count total no. species and organisms marked 6. use equation to estimate population size : **(total no. 1st sample x total no. 2nd sample)/ no. marked organisms)**

Answer 61

- capture as many organisms possible to increase sample size, ensuring reliable results - use nets or traps that don't injure/ harm the animal as can affect results (e.g. cover net trap to avoid rain/ predators) - mark using non-toxic paint or trackers - ensure mark doesn't fall off or intefere with daily activites or is easily noticeable by predators - give organism enough time to reintegrate with the rest of the population before recapture

Answer 62

- marked organism has enough time to reintegrate - definitive boundary - no marks fell off - few births - few deaths

Answer 63

**the process where an ecosystem will change over time** - occurs in a series of stages where at each stage, plant and animal communities in the area **slowly change their environment**, making it more suitable for other species with different adaptations - impact of these plants and animals leads to small change (e.g. in abiotic factors) | **results in biotic conditions change from abiotic conditions** - so communities of organisms **suceeded (replaced) by more adapted organisms**

Answer 64

- occurs when newly formed land/ sea levels fropped developing new land - no soil/ organic material to start with (so hostile species have to be tough)

Answer 65

1. colonisation by pioneer species 2. pioneer species change the environment and conditions 3. environment becomes less hostile for other/new species 4. change/increase in diversity/biodiversity 5. to climax community

Answer 66

1. **pioneer species colonises new land surface**: **live matter decomposers creating soil** so seeds/ spores carried by the wind begin to grow ( abiotic conditions are **very hostile** as limited water and nutrients due to lack of soil so pioneer species only species able to grow (adapted specially) 2. **when pioneer species die they're broken down by microorganisms that decompose that organic matter hummus** forming basic soil, changing environmental conditions making the area **less hostile maintaining water and nutrients so new organisms with different adaptations can grow** 3. organisms die and decompose, adds more organic materials forming deeper more **mineral rich soils**, nitrogen fixing bacteria makes ammonia used by plants to grow so they can **retain more water grow more changing conditions of environment making it less suitable for the previous species** 4. over time plants animals that are suited to environment move in **outcompeting original species** so better adapted ones become the **more dominant species** 5. as succession continues **ecosystem becomes more complex** as new species move in alongside existing species, **increasing biodiversity** is plants create habitats making abiotic conditions **less hostile** 6. results in **climax community**

Answer 67

- where the ecosystem is supporting the **largest/ most complex community** of plants and animals it can - as time goes on, this will remain in **steady state/ not change much**

Answer 68

depending on climate of ecosystem, this can affect what species make up the climax community

Answer 69

- occurs when **land previously occupied** with plants has been cleared of all plants but **soil remains** - can occur at **any stage after pioneer stage** - similar to primary but already soil present as starts at later stage and pioneer species larger

Answer 70

- prevent development of climax community - prevent succession - **plagioclimax-** succession stopped artificially (climax community)

Answer 71

the protection and management of a species and its habitat in a sustainable way

Answer 72

when there's enough resources available to meet the needs of people today witjout reducing the needs of people in the future

Answer 73

**must change with changes in ecosystem (often a conflict between conservation and human needs)** - management of succession - seed banks - captive breeding - fishing quotas - protected areas

Answer 74

- human activity interrupting succession - succession deliberately prevented to preserve ecosystem in its present state - e.g. **animal grazing-** eats growing tips of trees and shrubs, prevents development of climax community and halts succession - e.g. **set managed fires-** kills all plants, secondary succession occurs, pioneer species grow (these are plant species conerved)

Answer 75

- back up for conservation of different species grown in the wild - if plant is extinct/ lost from habitat, stored seeds used to reintroduce species - to ensure seeds are viable, need to test regularly ( which can be time consuming and expensive )

Answer 76

- breeding animals in **controlled environments** (e.g. in zoos to increase population size) - nearly extinct animals can be bred in captivity and released to wild, increasing no. preventing extinction - **animals bread in captivity may**: carry and spread disease, strugle to survive outside environment, lack natural instincts required for survival | (ex situ- off site)

Answer 77

- a limit to amount of a certain fish species that can be fished, to conserve species of fish as less killed, **reduce overfishing and extinction** - can reduce fishermen income - requires international co-operation - exceed quota results in fine - increases 'discards'- catch fish and throw back into sea

Answer 78

- protect habitat and species in them - e.g. natural reserves and natural parks - restricts urban/ industrial developments and farming - trees harvested with **coppicing**- trees cut to harvest wood, can still grow, no replant - frequently visited by tourists however, not easy to conserve

7: Genetics, Populations, Evolution and Ecosystems Flashcards

(103 cards)