Unit 10 - Classification and Evolution Flashcards

Question

What are the features of Bacteria?

Answer 1

- 70s ribosomes - RNA polymerase contains 5 proteins

Answer 2

- 80s ribosomes - RNA polymerase contains 12 proteins

Answer 3

Archaebacteria and Eubacteria.

Answer 4

Archaebacteria are known as ancient bacteria, while Eubacteria are known as true bacteria. Eubacteria are found in all environments, whereas Archaebacteria are more likely to be found in environments with extreme conditions.

Answer 5

Phylogeny is the study of the evolutionary relationships between organisms, which shows which organisms are related and how closely related they are.

Answer 6

Phylogenetic or evolutionary trees are branched diagrams representing evolutionary relationships between organisms and showing how different species evolved from a common ancestor.

Answer 7

- Phylogeny can be done without reference to Linnaean classification, which is a confusing system because it implies that different groups in each rank are equivalent - e.g. cats and orchids are both families, but orchids have existed far longer than cats - Unlike the hierarchical system, phylogeny produces a continuous tree - the lack of discrete taxonomic groups means that organisms are not placed into groups they do not fit into

Answer 8

Darwin's theory was originally published with Wallace in 1858, and his book On the Origin of Species, which popularised the theory, was published in 1859.

Answer 9

1. Offspring generally appear similar to their parents 2. No two individuals are identical 3. Organisms have the ability to produce large numbers of offspring 4. Populations in nature tend to remain fairly stable in size

Answer 10

Phenotype = the observable characteristics of an organism, determined by the organism's genes and by their environment

Answer 11

- resource availability - environment - biological factors

Answer 12

The process whereby organisms better adapted to their environment will survive to produce more offspring.

Answer 13

The individuals with those alleles will usually survive and produce more offspring, passing the alleles on.

Answer 14

A unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Answer 15

Wallace had independently created his own theory of evolution. As his theory was similar to Darwin's, the two theories were published as a joint paper.

Answer 16

- Both believed in natural selection - Their conclusions on how natural selection causes evolution were the same

Answer 17

- Darwin thought selection acted on individuals while Wallace thought it acted on groups or species - Darwin emphasised competition within populations as the driving force for evolution, whereas Wallace put more emphasis on the species meeting the demands of a change in their environment - Darwin also explained evolution through sexual selection, which Wallace disregarded

Answer 18

- Darwin's book On the Origin of Species popularised the theory - He was the first to present evidence for the theory - His version of the theory contains more individual theories than natural selection, like sexual selection

Answer 19

The remains or impression or a prehistoric plant or animal embedded in rock and preserved in petrified form.

Answer 20

The horse.

Answer 21

- Simple fossils are found in older rocks than fossils of complex organisms - The sequence in which fossils are found matches the organisms' ecological links to each other - By studying similarities in the anatomy of fossils, scientists can show how closely related organisms have evolved from the same ancestor - Fossils allow relationships between extinct and extant organisms to be investigated

Answer 22

An ancestral organism shared by two or more descendent lineages.

Answer 23

Scientists research slight changes occurring in cytochrome C and rRNA. To find out how closely two species are related, the molecular sequence of a molecule is compared. Species that are closely related have the most similar DNA. rRNA is often used because it has a very slow rate of substitution.

Answer 24

The DNA would be very similar.

Answer 25

The DNA would be quite different.

Answer 26

Organisms that are distantly related have had more time since they shared a common ancestor, so mutations have accumulated in their DNA, while more closely related organisms haven't had time for enough mutations to occur to make their DNA sequences significantly different.

Answer 27

Variation = differences in characteristics between organisms

Answer 28

Variation between individuals of different species.

Answer 29

Variation between individuals of the same species.

Answer 30

Genetic causes or environmental causes. Most characteristics are caused by a combination of genetics and environmental factors.

Answer 31

Mutations - sudden changes in DNA Fusion of gametes at fertilisation - the offspring will inherit characteristics from both parents and which genes are inherited differs as gamete fusion is random Meiosis - crossing over and independent assortment lead to variation Alleles - no organisms will have the same alleles/gene variants

Answer 32

Asexual reproduction produces clones, which have exactly the same genetic material as the parent, so genetic information in those organisms can only be increased through mutations.

Answer 33

Where there are two extremes and a full range of intermediate values. Most individuals are close to the mean and the number of individuals at the extremes is low.

Answer 34

Continuous variation is usually regulated by multiple genes and can be influenced by the environment in which an organism lives.

Answer 35

Where there are two or more distinct categories with no intermediate values. The members of a species may be evenly distributed between the different forms, or there may be more of one type than the other.

Answer 36

Discontinuous variation is usually regulated by a single gene and is not influenced by the environment in which an organism lives.

Answer 37

A normal distribution.

Answer 38

The mean, median and mode are the same, in the middle of the curve. Most values lie close to the mean, and the number of individuals at the extremes is low.

Answer 39

A measure of the variation within a sample.

Answer 40

Standard deviation is represented by the width of a normal distribution curve.

Answer 41

If SD is low, there is less variation, and if SD is high, there is more variation.

Answer 42

To compare the means of data values of two populations.

Answer 43

sample size - number of data sets

Answer 44

1. Calculate the mean for each data set 2. Calculate the standard deviation for each data set 3. Put the values into the t test equation and calculate the value of t 4. Calculate the degrees of freedom 5. Compare the t value to the significance table at 5% or 0.05 6. If t is lower than the value in the table, there is no significant difference between the means of the data sets and therefore any variation is likely due to chance. If t is greater than the value in the table, there is a significant difference between the means of the data sets and therefore any variation is unlikely to be due to chance.

Answer 45

1. Rank the data from smallest to highest, with 1 being the highest 2. Repeat for the second data set 3. Find the difference between the ranks and square it (d2) 4. Put the values into the equation and calculate the correlation coefficient 5. Compare the value to the critical value (using the number of pairs of data as n) - if the value is lower than the critical value, we accept the null hypothesis, and if it is higher, we reject the null hypothesis

Answer 46

Adaptations = characteristics which increase an organism’s chances of survival and reproduction in its unique environment

Answer 47

Anatomical, behavioural and physiological.

Answer 48

Body coverings - in animals could be hair, scales, spines, feathers, shells etc, and waxy layers and spikes in plants Camouflage - the outer colour of an animal allows it to blend into the environment, making it more invisible to predators Teeth - the shape and type are related to the animal’s diet; herbivores have consistently growing teeth while carnivores have sharp canine teeth Mimicry - copying another organism’s appearance or sounds allows a harmless organism to fool predators into thinking it is poisonous or dangerous

Answer 49

Survival behaviours Courtship - increases the organism’s chances of reproduction by helping to attract a mate Seasonal behaviours which help the organism cope with environmental changes, such as: Migration - moving from region to region for a better climate/food source Hibernation - a period of inactivity in which an animal’s body temperature, heart rate and breathing rate slow down to conserve energy, reducing the animal’s requirements for food

Answer 50

Behavioural adaptations can be innate/instinctive (inherited through genes) or learned through experience or observing other animals.

Answer 51

Poison production - many reptiles produce venom to kill their prey and many plants produce poisons in their leaves to protect themselves from being eaten Antibiotic production - some bacteria produce antibiotics to kill other species of bacteria in the surrounding area Water holding - enables organisms to survive for long periods without access to water Reflexes - e.g. blinking Temperature regulation

Answer 52

Convergent evolution = when unrelated species begin to share similar traits

Answer 53

Analogous structures = structures which have a different genetic origin but have adapted to perform the same function

Answer 54

Aloe and agave - they have both adapted to survive in the desert but evolved entirely separately, with aloe having evolved in sub-Saharan Africa while agave evolved in Mexico and the southern United States.

Answer 55

Despite the geographical and temporal separation between marsupials and placental mammals (their last common ancestor was over 100 million years ago) they bear a strong resemblance in overall shape, type of locomotion and feeding techniques because they have adapted to similar climates and food supplies. However, their distinct evolutionary relationships are reflected in their different methods of reproduction. In placental mammals, a placenta connects the embryo to its mother’s circulatory system in the uterus. Marsupials start life in the uterus, but leave and enter the marsupium while they are embryos, completing their development by suckling milk.

Answer 56

Marsupial mice and placental mice - both are small, agile climbers that live in dense ground cover and forage at night for small food items Flying phalangers and flying squirrels - both are gliders which eat insects and plants, and both have skin stretched between their forelimbs and hind limbs to provide a large surface area for gliding between trees Marsupial moles and placental moles - both burrow through soft soil to find worms and grubs, have a streamlined body shape and forelimbs for digging and have velvety fur to allow smooth movement through the soil, but the marsupial mole ranges in colour from white to orange whereas the placental mole is grey

Answer 57

Selection pressures = external agents that affect an organism’s ability to survive in a given environment

Answer 58

Organisms within a species show variation in their characteristics that are caused by differences in their genes, such as different alleles of a gene for a particular characteristic. New alleles can arise by mutation. Organisms whose characteristics are best adapted to the selection pressure have an increased chance of surviving and successfully reproducing. Less well-adapted organisms die or fail to reproduce. Successful organisms pass the allele encoding the advantageous characteristic onto their offspring. Conversely, organisms possessing the disadvantageous allele are less likely to successfully pass it on. This process is repeated for every generation. Over time, the proportion of individuals with the advantageous adaptation increases. Therefore, the frequency of the allele that codes for this particular characteristic increases in the population’s gene pool. Over very long periods of time and many generations, often involving multiple genes, this process can lead to the evolution of a new species.

Answer 59

Methicillin-resistant Staphylococcus aureus (MRSA) has developed resistance to many antibiotics, including methicillin Bacteria evolve in a short time due to reproducing very quickly Usually, mutations in bacteria result in their death, but a mutation in S. aureus provided resistance to methicillin When the bacteria were exposed to methicillin, resistant individuals survived and reproduced, passing the allele for resistance on to their offspring, while non-resistant individuals died Over time, the number of resistant individuals in the population increased until a resistant strain had evolved

Answer 60

Before the industrial revolution, most peppered moths were pale in colour, providing camouflage against tree bark - this increased their chances of survival as darker-coloured moths were eaten by birds During the industrial revolution, many trees became darker due to being covered in soot or a loss of lichen cover (caused by increased atmospheric pollution) - this meant more dark peppered moths survived and reproduced, passing on the ‘dark’ allele This increased the frequency of this allele, and of darker peppered moths, in the population After a few years, there were more dark than light peppered moths in areas close to industrial towns and cities Since the Clean Air Act of 1956, steps have been taken to improve air quality in towns and cities and to reduce the level of pollution released from factories The frequency of lighter peppered moths has increased again

Answer 61

Sheep blowflies cause a condition called flystrike in sheep, which can be fatal In the 1950s in Australia, the pesticide diazinon was used to kill blowflies, preventing flystrike Within six years, blowflies had developed high resistance to diazinon, as individuals with resistance had survived exposure, passing on the resistant allele - this allowed a resistant population to evolve Scientists extracted DNA from a sample of 70-year-old blowflies kept at the Australian Natural Insect Collection It was found that the older blowflies did not have resistance to diazinon (unlike the modern species), but both the older and modern blowflies had resistance to malathion (a similar pesticide) The scientists concluded that pre-adaptation contributed to the development of diazinon resistance - the pre-existing resistance to malathion allowed the blowflies to develop first resistance to organophosphate chemicals (the type of chemical which diazinon and malathion are) generally and eventually resistance to diazinon specifically

Answer 62

Scientists have discovered a new strain of Flavobacterium living in waste water from factories which produce nylon 6 (used to make toothbrushes, violin strings etc.) This strain of bacteria has evolved to digest nylon using enzymes called nylonases - this is beneficial to humans because it helps clear up factory waste, and to the bacteria because it provides them with another nutrient source Nylonases are unlike any enzymes found in other strains of Flavobacterium and do not help digest any other known material Most scientists believe that the mutation producing these enzymes was a result of a gene duplication combined with a frameshift mutation

Unit 10 - Classification and Evolution Flashcards

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