TOPIC 7: Genetics, populations, evolution and ecosystems Flashcards

Question

# ***3.7.1 Inheritance*** Genetic diagram coding of codominance.

Answer 1

Gene^allele example: C^R C^W

Answer 2

C^R = allele for red pigment production. C^W = allele for white pigment production. **HOMOZYGOUS = C^R C^R and C^W C^W** **Parental phenotype:** Red coat White coat. **Parental genotype:** C^R C^R and C^W C^W **Gametes:** C^RC^R = C^R C^R C^WC^W = C^W C^W **Offspring genotypes:** *punnet square of the gametes to result in* **Offspring phenotype:** 100% roan coat (C^RC^W)

Answer 3

**HETEROZYGOUS = C^RC^W** **Parental phenotype:**roan coat & roan coat **Parental genotype:** C^RC^W & C^RC^W **Gametes:** C^RC^W = C^R C^W C^RC^W = C^R C^W **Offspring genotype:** *punnet square of the gametes to result in* **Offspring phenotype:** 50% = roan coat = C^RC^W 25% = red coat = C^RC^R 25% = white coat = C^WC^W

Answer 4

**More than 2 alleles** for a **1 gene.**

Answer 5

Gene^allele example: I^A I^O I^B I^O

Answer 6

AB in plasma = Anti-B Antigen in RBC = Antigen A

Answer 7

AB in plasma = Anti-A Antigen in RBC = Antigen B

Answer 8

AB in plasma = none Antigen in RBC = Antigen A and B

Answer 9

AB in plasma = Anti-A and B Antigen in RBC = none

Answer 10

Blood group A = I^A I^O or I^A I^A Blood group B = I^B I^O or I^B I^B Blood group AB = I^A I^B Blood group O = I^O I^O A = dominant B = dominant AB = codominant O = recessive.

Answer 11

Two genes carried on / located on the **same chromosome** = autosome. From the chromosome 1-23 the 23rd chromosome = sex chromosome ( X or Y)

Answer 12

NO crossing over All linked genes remian together in meiosis forming gametes then offspring.

Answer 13

**Two linked genes:** 1. body colour = grey = dominant = G black = recessive = g 2. wing size normal = dominant = N vestigial = recessive = n Grey normal = GN Grey vestigial = Gn Black normal = gN Black vestigial = gn **Parental phenotype:** Grey body & Grey body. **Parental genotype:** GB = Gg Nn GB = Gg Nn **Gametes:** GB = GN & gn GB = GN & gn **Offspring phenotype:** *punnet square using the gametes to result in* **Offspring genotype:** **3 x fruit flies** = grey body and normal wings 1x GGNN 2xGgNn **1 x fruit flies** = black body and vestigial wings 1x ggnn

Answer 14

**3 fruit flies:** Linked No crossing over More common. **1 fruit fly:** Not linked Crossing over occurs More rare.

Answer 15

A gene whose locus os on the **X chromosome**

Answer 16

Chromsome^allele example: X^R X^r

Answer 17

Disorder caused by a **defective gene** on the X chromosome.

Answer 18

Blood clots slowly. Slow and persistent leading to internal bleeding. Lethal if not treated. Some selective removal of gene population = occurenece = rare = 1 in 20000 in europe

Answer 19

Recessive allel with an **altered sequence of DNA nucleotides** which codes for a **faulty protein** = does not function. Indivduals are unable to produce functional protein required for the **clotting process**

Answer 20

**H = dominant = allele for the production of clotting protein** = rapid blood clot **h = recessive = allele for the non-production of clotting protein** = slow blood clot. } always attached to X chromosome = X^H X^h **Parental phenotype:** Carrier female & normal male. **Parental genotype:** CF = X^H X^h NM = X^H Y **Gametes:** CF = X^H & X^h NM = X^H & Y **Offspring genotype:** *punnet square using the gametes to result in* **Offspring phenotype:** 25% normal female = X^H X^H 25% normal male = X^H Y 25% carrier female = X^H X^h 25% haemophilliac male = X^h Y

Answer 21

One gene **influences** (affects / masks) the expression of another gene. example = dihydrid = 2 genes = one masks the other one. example = coat colour in mice, coat colour in Labradors, fruit colour of vegetables.

Answer 22

Controlled by 2 genes **GENE 1** controls for expression of pigment *allele E* = dominant = codes for pigment production. *allele e* = recessive = does not code for pigment production so **FUR IS YELLOW** **GENE 2** controls which pigment is expressed. *allele B* = dominant = black fur *allele b* = recessive = brown fur **Parental phenotype:** Black fur & black fur **Parental genotype:** EeBb & EeBb **Gametes** EeBb = EB Eb eB eb EeBb = EB Eb eB eb **Offspring genotype:** *punnet square using gametes to result in* **Offspring phenotype:** **9 x black fur** = 1x EEBB 2 x EEBb 2 x EeBB 4 x EeBb **3 x brown fur** = 1 x EEbb 2 x Eebb **4 x no pigment produced** = 1x eeBB 2 x eeBb 1 x eebb

Answer 23

Can be used to measure the **inheritance of sex-linked characters** such as haemophillia. **KEY SYMBOLS** *Square* = male *Circle* = female *Shaded square or circle (affected male or female)* = indicates prescence of character i.e. haemophillia in the phenotype.

Answer 24

**All the alleles of all the genes** in a population at one time.

Answer 25

All the indivduals of **one species** in **one area at one time** that **can be interbreeded.**

Answer 26

proportion of an allele within a the gene pool. = how often an allele occurs in a population = answer will be a decimal or a percentage

Answer 27

Exist as one or more populations.

Answer 28

A mathematical model that makes assumptions which **impedes** (interferes with) the **accuracy**. It assumes **no change** in allele frequency between generations within a population } not accurate assumption.

Answer 29

1. It must be a **large population** where there is **NO immigration, emigration, mutation or natural selection.** 2. **Random mating** = all possible genotypes can breed with every other genotype and no in breeding.

Answer 30

p^2 + 2pq + q^2 = 1 p^2 = frequency of **homozygous dominant** genotype 2pq = frequency of **heterozygous dominant** genotype = expresses dominant but carries a recessive allele. q^2 = frequency of **homozygous recessive** allele. 1 = whole population. **SIMULATANEOUSLY USE THIS EQUATION TOO:** p + q = 1 P = frequency of dominant allele q = frequency of reccesive allele.

Answer 31

Due to the genetic differences that occur as indivudals of a population will have **different alleles of the same gene** Genetic variation arises because of: 1. **Mutations:** Sudden changes to genes and chromosomes could be passed onto next generation. 2. **Meisosis:** Nuclear divison = new combination of alleles **before** being passed into gametes. 3. **Random fertilisation of gametes:** sexual reproduction = gametes fusing is a random process = new combination of alleles are produced = offspring different from parent.

Answer 32

Their variation is increased by all 3 methods = mutations, meisosis and random fertilisation of gametes. Meisosis and RFG = sexual reproduction leads to **further genetic variation**

Answer 33

1. Climate conditions = temperature, rainfall, sunlight. 2. Soil conditions 3. pH 4. Food availability.

Answer 34

Natural selection occurs.

Answer 35

Mutation. Meisosis and RFG produces further genetic variation.

Answer 36

Each organism is subjected to the process of selection based on its suitability for survival under conditions at that time.

Answer 37

Determine the **frequency of alleles** within the gene pool. Environmental factors that can **limit** a population. 1. Predation 2. Disease 3. Competition

Answer 38

1. Organisms that produce **more offsprings** than the availability of food, light and space. 2. Genetic variation within the **populations** of all species. 3. Variety of phenotypes that selection will operate against.

Answer 39

Too many offsprings for the available resources leading to competion between indivduals; **intraspecific competition** More competition = more individuals will die but deaths are not random. Organisms with phenotypes that provide **selective advantges** are more likely to **survive and reproduce** **Pass on the favourable alleles** to the next generation.

Answer 40

Differential reproductive success. = certain indivduals can reproduce and so the effect of differential reproductive success is that there is a **change in the allele frequency** within the gene pool.

Answer 41

1. Stabilising 2. Directional 3. Disruptive.

Answer 42

It preserves the **average phenotype** (around the mean) of a population by favouring **average indivduals** Selection **against** extremem phenotypes i.e. too low or too high. Occurs when environmental conditions are **constant** over time.

Answer 43

HOT TEMP: short fur mammals have an advantge as they can lose body heat more rapidly. COLD TEMP: long fur mammals have an advantge as they can preserve more body heat. CONSTANT TEMP: 10 degrees C indivduals at extreme ends i.e HOT & COLD will not survive.

Answer 44

Within a population there is a range of genetically different indivduals of one phenotype. If environmental conditions change so will the optimum value for survival. DS results in one extreme of the range of variation being selected than the other or even the mean. **SELECTION PRESSURE:** favours the combination of alleles that cause the mean moving right or left of its original position.

Answer 45

*BELL SHAPED CURVE WITH FUR LENGTH INCREASING BY 0.5CM AND 1.5CM IS THE OPTIMUM* 1. OPTIMUM FUR LENGTH AT 10 degrees C = 1.5cm 2. If temperature falls to 5 degrees C then the indivduals with 2.0 cm and more of fur length are **better insulated**; can survive and reproduce. 3. Hence the selection pressure **favours** indivduals with the longest fur i.e. right side. 4. The selection pressure causes a **shift in mean** towards the **longer fur** over generations. Selection pressure will continue. 5. Selection pressure **further shifts the mean fur length to the right** until 2.0cm is reached. 2.0cm is now the optimum length of fur for 5 degrees C. Selection pressure **ceases**.

Answer 46

Occurs when an environmental factors such as temperature take 2 distinct forms. Indivduals that contain the **extreme tratis** are more likely to survive and reproduce and pass on their alleles. Allele frequency will change as more wil begin to posses the allele for the extreme trait. Middle trait will become **less frequent**

Answer 47

Temp that alters between 5 degrees in the winter and 15 degrees in the summer. Can lead to 2 seperate species of the mammal 1. Long fur and active in the winter. 2. Short fur and active in the summer.

Answer 48

Evolution of new species from exisiting ones. Occurs when an original population of the same species becomes **reproductively isolated** = they are 2 populations of the same species but they cannot breed together due to differences in their gene pool.

Answer 49

Populations are **A**way / seperated geographically leading to reproductibe isolation such as moutain ranges, new water bodies. Geographical sepearation may result in a **physical barrier** between the 2 populations preventing them from interbreeding. They will both have different benefical mutations to help them survive in environments. The accumulation of DNA differences over time will become **so genetically different** they would be **unable** to interbreed + reproduce.

Answer 50

A population in the same area that leads them to become **reproductively isolated** due to differences in their **behaviour**. Reproductively isolated because of **random mutations** that could impact reproductive behaviour. For example: performing different courtship rituals or indivduals being fertile at different times of the year. Reproductive isolated populations will accumulate **different mutations**. DNA is different so **unable to interbreed and reproduce** because there is **no gene flow** between the 2 groups = 2 species.

Answer 51

When **chance** (not environmental selection pressures) lead to a change in the allele frequency then to speciation due to evolution via natural selection. Will **only** impact **small populations** as there is a **bigger impact** of changes in the allele frequency that is passed onto the next generation. Over time, some alleles can be **lost** or **favoured** by chance. Evolution occurs **more rapidly** in smaller populations as in large populations as changes in the allele frequencies due to genetic drift will **even out** across the whole population.

Answer 52

All the indivduals of **one species** in **one area at one time** that **can be interbreeded.**

Answer 53

A population of different species in the **same area** at the **same time**.

Answer 54

A **community and the non-living components** of environment (biotic and abiotic factors). Can range in size (small-large)

Answer 55

Part of an ecosystem where an organism lives and occupies a niche goverened by adaptations to biotic and abiotic conditions.

Answer 56

An organism's **role** within an ecosystem = position in the food web and habitat.

Answer 57

**NONE** **1 species** has it **own niche** which is governed by adaptations to biotic and abioitc conditions in order to survive and reproduce.

Answer 58

Impact of interactions between organisms

Answer 59

**non-living** conditions of an ecosystem such as temperature, light, humidity.

Answer 60

The size of population of species that an ecosystem can support.

Answer 61

1. The effect of abiotic factors. 2. Interactions between organisms: intra and interspecific competition and predation.

Answer 62

**TEMPERATURE** Each species has different optimum temperatures. i.e. Cold blooded animals and plants: if there's a **decrease in temperature** below the optimum then enzymes will begin to work slowly, metabolic rate is slower so the population has a small carrying capacity. **LIGHT** **Increase in light intensity**, increase photosythesis rate, increase plant growth, more seeds are produced, carrying capacity is larger = animals that feed on these plants have **larger carrying capacity.** **pH** Affects enzyme action. The population of organisms is larger when there is a suitable pH. **WATER AND HUMIDITY** Water: only well adapted species live in dry conditions. Humidity: affects the transpiration rates in plants and evapouration of water from the bodies of animals.

Answer 63

Members of **different species** are in competition for the same resources (water,food,light) that is **limited in supply**. One species has a **competitive advantge** due to its adaptation to the environment. So the population size of that species will **increase** and the other one will **decrease** , could cause them to become **extinct** if conditions are the same.

Answer 64

No two species occupy the same niche.

Answer 65

Members of the **same species** that are in competition for resources and mates. The greater the availability of resources = larger population. i.e: robins that compete for breeding territory. Female birds are only attracted to males who established their territory allowing them to gain more food, interbreed, reproduce and pass on adaptations.

Answer 66

Predation = when an organism is consumed by another one. 1. **Predator eats prey** = reduces population of prey. 2. **Fewer prey available** = competiton **between predators** for the preys that are left behind. 3. **Predator population reduced** = unable to ibtain prey for their survival and hence die so cannot reproduce. 4. **Fewer predators** = **increase in prey** = survive, and reproduce 5. **Predator population will increase** as the prey population increased.

Answer 67

To estimate the size of a population of motile animals.

Answer 68

1. **Intial sample** of population is captured. 2. Indivduals are **marked then released** back into the wild. Number of caught is **recorded**. Mark must be weather resistant. 3. Left for a period of time to allow them to **randomly disperse** throughout habitat. 4. **Second sample** is captured. Number of caught is **recorded**. The number of **recaptured** is also recorded. 5. Equation to estimate the size of the population: Estimated total population = (Number of organisms **intially** caught X number of organisms in the **second** sample) / number of **marked organism recaptured**. 6. Repeat test = more times repeated = more reliable.

Answer 69

How you capture and how you mark must cause **no permanent harm** Considerations for the mark: 1. Non-toxic 2. Must not increase chance of predation. 3. Must not increase chance of reproduction (courtship rituals) 4. Must not interrupt with a bird's ability to fly.

Answer 70

1. The population size is **constant** = no birth, no death, no immigration or emigration. } These things will definately happen 2. Animals will always **redistribute evenly** } Animals may huddle in a particular area because of food, water or shelter from weather conditions or predators.

Answer 71

Sampling is more time efficient and can be accurate if implemented correctly.

Answer 72

1. Random sampling: in uniform areas to avoid bias. 2. Line transect to examine a change over distance. 3. Large sample (+30)

Answer 73

sample using a quadrat. Random sampling = uniform distribution. Line transect = uneven distribution.

Answer 74

1. Lie 2 tapes measures at a **right angle** to create a gridded area. 2. Use a **random number generator** to generate **2 coordinates** 3. Place quadrat and collect data (density/percentage cover or frequency). 4. Repeat test at least 30 times and calculate a mean.

Answer 75

Used to estimate a population size when they are **unevenly distrubted** e:g: populations which change over distance. Gives you a sample of different sections. examples: Sandy/ rocky shores. Across a path or river.

Answer 76

Belt transects = quadrat is placed at **every position** along the tape measure. } for slow or non-motile organisms. Interrupted belt transects = quadrat placed a **uniform intervals** along tape measure i.e: every 5 metres = can see quicker difference.

Answer 77

1. **Place a tape measure at a right angle to the shore line.** 2. Place quadrat at every 5 metres for interrupted belt transects or at every position for belt transect. 3. Collect the data (density/ percentage cover/ frequency) 4. **Repeat by placing another 30 transects along the beach at a right angle to shore line.**

Answer 78

**% of squares in a quadrat with the species present. (there are 100 squares)** **Pros:** Quick method to sample a large area. Useful if too difficult to identifty organism such as moss or too many to count such as grass. **Cons:** Poor accuracy = doesn't consider overlapping of plants (might be more underneath) or the size of plants (one plant = big = occupy entire quadrat)

Answer 79

**Number of one whole species in a given area** = open quadrat is used. i.e 11 daisies in quadrat in 0.5m x 0.5m = 0.25m2 whole field = 280m2 (280/0.25) x 11 = 12320 species in entire field. **Pros:** More accurate = easily distinguish indivdual plant and not too many to count. Can be used to estimate species richness = count number of different species present. **Cons:** time consuming.

Answer 80

**Proporation of ground occupied by the species** = how many full squares are occupied by species. **Pros:** Quicker method than density. Useful if too difficult to identify = moss or too many to count = grass. **Cons:** Subjective = limits accuracy. Doesn't consider overlapping plant (more underneath) or size of plants (one plant = big = occupy entire quadrat)

Answer 81

Changes **over time** in the species that occupy a particular area.

Answer 82

When bare rock or other barren land is **first colonised** which can arise as a result of 1. Sand piled into dunes by wind or sea 2. Volcanoes erupting and deposing lava.

Answer 83

Dynamic systems. Changes day to day as populations fluctuate, slowly or rapidly.

Answer 84

**Colonisation by pioneer species to climax community.** Pioneer species colonise bare rock or bare sand } has high conc. of salt from the ocean.

Answer 85

Lichen = they are adapted to survive **harsh abiotic factors** Lichen exists as **2 species** algae and fungus = symbiotic relationship. Algae can **photosynthesise** to make glucose. Fungus can **absorb water** and release enzymes outside the cell (extracellular breakdown) onto the rocks and release mineral ions which are absorbed by the **algae and fungi**

Answer 86

Thin layer of soil is formed = **humus** which provides nutrients to support the community of small plants i.e. mosses + more smaller plants As the abiotic factors now become **less harsh** the larger plants can now survive and change environment, making it **less suitable for the previous species hence they are outcompeted** Results in a **less hostile environment** and an **increase in biodiversity** i.e. shrubs = climax community.

Answer 87

When land that has already sustained life i.e. had trees growing has been altered / disrupted or the plants have been destroyed due to human activity such as land clearance for agriculture or a forest fire. Succession will start again from soil and not bare rock. Soil already exisiting = spores and seeds often remain alive in the soil and there's an influx of animal and plants through dispersal and migration from surrounding area. Soil already exisiting = allows some plants to grow and flourish whereas before they couldn't due to large plants surrounding them.

Answer 88

Mangement of earths natural resources by humans that maximises the use of them in the future. Conservation of habitats involves managing succession.

Answer 89

1.**PERSONAL:** to maintain our planet and life support system. 2.**ETHICAL:** other species occupying earth longer than us. 3.**ECONOMIC:** living organisms contain large amounts of genes to make millions of substances. 4.**CULTURAL:** habitats and organisms enrich our lives. Add interests to life and inspires poets, writers and artists.

Answer 90

Prevents climax community. Greater variety of habitats are conserved which increases biodiversity. Management between the conflict between human needs and conservation to maintain sustainability of natural resources such as forest being **coppiced** = trees (climax community) are not completely pulled out of the ground but are cut down to the base. Wood is produced which can be used for timber = used for builiding products. There is also now an area where different species can thrive whereas in the climax community they were **outcompeted.**