classification

Question 1

what is classification and taxonomy

Answer 1

act of arranging organisms based on their similarities and differences to make it easier for studying.Taxonomy is the study of classification and classification systems are placed in ataxinomic hierarchy.

Question 2

Describe the principles of biological classification.

Answer 2

Organisms are classified into a hierarchy of groups, which are subdivided into smaller groups.
Classification is based on shared features, which may be morphological, biochemical, or genetic.
The groups do not overlap — an organism belongs to only one group at each level of the hierarchy.

Question 3

What is the order of classification / taxonomic groups? (i.e. class, genus etc. in order)

Answer 3

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 4

What is the name of the groups of classification (i.e. class, genus etc.)?
What were the traditional 5 kingdoms?

Answer 4

Taxonomic groups
Animalia, Fungi, Protoctista, Plantae, Prokaryotae

Question 5

Who was the first to propose a modern system of classification and when?
What is the binomial naming system?
What is an advantage of using the binomial naming system?

Answer 5

Carl Linnaeus in the 18th century, hence it being named Linnaen Classification
Where we use the Genus and Species names (in that order) to identify a species.Genus part of the name has an upper case first letter, species part of the name has a lower case first letter.and always written in italics or underlined.
It removes the language barrier between two scientists without a common language who wish to talk about the same organism.

Question 6

Can organisms in the same genus reproduce?
What is the infertile offspring of two organisms of the same genus called?

Answer 6

yes, but they only produce infertile offspring
A hybrid, and has no Latin name

Question 7

When was the 6-kingdom model of classification with domains first introduced and by whom?
What are 3 reasons that scientists classify organisms?
What is one slight limitation of using a classification system?

Answer 7

1977 by Carl Woese
To identify species 2. To predict characteristics 3. To find evolutionary links
The classification is created by humans instead of being defined by nature.

Question 8

what are the 5 kingdoms and the features of them

Question 9

what is phylogeny

Answer 9

the study of the evolutionary history of groups of organisms. it tells whose related to whom and how closely related they are.

Question 10

What does a phylogenetic tree do?

what is a species based on phylogenetic tree.

Answer 10

Help us see relationships between organisms and common ancestors.
the smallest group that shares a common ancestor.
the smallest group that shares a common ancestor.

Question 11

Explain what phylogenetic trees show.

Answer 11

Explain what phylogenetic trees show.
A:
Phylogenetic trees illustrate the evolutionary relationships between organisms.
The closer the branches, the more closely related the organisms are.
Close branches mean they share a recent common ancestor.
Distant branches = organisms are less closely related, with a more distant ancestor.
The branch points (nodes) represent a common ancestor.
The length of branches (if shown) indicates the amount of evolutionary change or the time since divergence.
Phylogeny reflects the idea that all organisms have evolved from a common ancestor.

Question 12

application q

Answer 12

phone p263

Question 13

How can classification use phylogeny?

Answer 13

Organisms can be classified according to their evolutionary relationships.
Species that share a recent common ancestor are placed in the same group or clade.
Phylogeny can be determined using morphological, biochemical, or genetic data.

Question 14

What are two advantages of phylogeny over traditional classification?

Answer 14

It reflects evolutionary relationships rather than just physical similarities.
It uses molecular or genetic data, which is more accurate than relying on observable features alone.

Question 15

What does it mean when a branch on a phylogenetic tree does not make it to the top of the diagram (i.e. the modern day)?

Answer 15

the species is extinct

Question 16

what is cladistics

Answer 16

What is cladistics?
OCR-markscheme style answer (3–4 marks):
Cladistics is a method of classification based on evolutionary ancestry.
Organisms are grouped into clades, which include a common ancestor and all its descendants.
It uses shared derived characteristics, often from DNA or protein sequence data, to determine relationships.
Shown as a cladogram, a branching diagram of evolutionary relationships.

Question 17

How did early classification systems work, and why are modern methods better?

Answer 17

•Early systems: Used only observable features (anatomical or behavioral) to group organisms.
•Example: Number of legs, living in groups, habitat.
•Problem: Scientists might disagree on which features are most important; similar-looking organisms aren’t always closely related.
•Example: Sharks and whales both live in the sea and look similar, but sharks are cartilaginous fish, and whales are mammals.

•Modern systems: Use observable features plus additional evidence to show evolutionary relationships.
•Types of evidence: embryological, fossil, and molecular.
•This helps classify organisms based on how closely related they really are.

Question 18

Molecular evidence for classification

Answer 18

Gathering molecular evidence involves analysing the similarities in proteins and DNA. More closely related organisms will have more similar molecules.
You can compare things like how DNA is stored and the sequence of DNA bases.

You can also compare sequence of amino acids in proteins from a. Different organisms
eg cyctochrome C is a short protein found in many species. The more similar the amino acids sequence of cytochrome C in 2 diff species the more closely related the species are likely to be.

Question 19

How has new technology changed classification?

Answer 19

New technologies (e.g. new DNA analysis techniques, better microscopes) can result in new discoveries being made. Scientists can share their new discoveries in meetings and scientific journals.
How organisms are classified is continually revised to take account of any new findings that scientists discover.

Question 21

Compare the new 3 domain system with the older 5 kingdom system.

Answer 21

Kingdom – organisms placed into one of the following groups: Animalia, Plantae, Fungi, Protoctista & Prokaryotae.
Domains - Prokaryotes (cells without a nucleus) are now divided into 2 domains – Archea and bacteria. Eukaryotes (cells with a nucleus) are placed in the domain Eukarya.

Question 22

Why was the classification system changed & the 3 domain system introduced?

Answer 22

New evidence, mainly molecular showed large differences between Archea & Bacteria – evidence suggests that these two groups evolved separately. The classification system changed to reflect this new evidence.

Question 23

Why were prokaryotes reclassified into two domains, Archaea and Bacteria?

Answer 23

the prokaryotes were reclassified Ito 2 domains because new evidence showed large difference between the archea and bacteria.
the new evidence is:
molecular evidence:
the enzyme ran polymerase (for making ran) is different in bacteria and arches.archea but not bacteria have similar histones to eukarya

cellular evidence; the bonds of the lipids in. the cell membranes of bacteria and arches are different.the development and composition of flagella are also different
most scientist now argue that archer and bacteria evolved speeratley and archer are more closely related to euarya than bacteria.the three domain system reflects how different the arch and bacteria are.

Question 24

what is variation

Answer 24

Variation is the differences that exist between individuals.

Question 25

what is infraspecific and interspecific variation

Answer 25

Variation within a species-Individual European robins weigh between 16g and 22g and show some variation In many other characteristics including length wingspan colour and break size. The variation between different species-The lightest species of bird is the bee hummingbird, which weighs aroun: 422 1.6 g on average. The heaviest species of bird is the ostrich, which can weigh up to 160 kg (100 000 times as much).

Question 26

what is continuous variation

Answer 26

when the individuals in a population vary within a range-no distinct categories. eg Animals-Height — humans can be any height within a range a range,not just tall or short • Mass — humans can be any mass within a range. Milk yield-cows can produce any volume of milk within a range Plants- surface area of leaves-the surface area if each of a trees leaves can be any value within a range Mass-the mass of the seed from a flower head varies. Micro-organisms-width-of e coli bacteria varies within a range Length- length of flagellum varies

Question 27

discontinuous variation

Answer 27

when there are 2 or more distinct categories-eahc individual falls into only one of these examples and there are no intermediates. example When there are two or more categories-each individual falls into each one of these categories and there’s no intermediates. Example- Animals Blood group - humans can be group A, B, AB or O (see Figure 3). Plants-Colour - courgettes are either yellow, dark green or light green. Seed shape — some pea plants have smooth seeds and some have wrinkled seeds. Microorganisms-Anyibiotic resistance -bacteria are either resistant or not. Pigment production-some types of bacteria can produce a coloured pigment some cannot.

Question 28

CAUSES OF VARIATION

Answer 28

genetic factors environmental factors both of them

Question 29

what's the genetic factors

Answer 29

Diff species have different genes. Individuals of the same species have the same genes, but different versions of them (called alleles). The alleles an organism has make up its genotype. The differences in genotype result in variation in phenotype — the characteristics displayed by an organism. Example: Variation caused by genetic factors includes: • Eye colour in humans (which can be blue, green, grey, brown), • Blood type in humans (O, A, B or AB), • Antibiotic resistance in bacteria. You inherit your genes from your parents. This means variation caused by genetic factors is inherited.

Question 30

what's the environmental factors

Answer 30

Variation can also be caused by differences in the environment, e.g. climate, food, lifestyle, Characteristics controlled by environmental factors can change over an organism's life. Example Variation caused only by environmental factors includes accents and whether people have pierced ears.

Question 31

What are the 3 genetic causes of variation?

Answer 31

Crossing over of chromatids during meiosis Independent assortment of chromosomes during meiosis Random fertilisation of gametes

Question 32

explain genetic and environmental factors

Answer 32

genetic factors determine the characteristics an organisms own with but environmental factors influence how some characteristics develop eg height-genes determine how tall an organism can grow eg. tall parents tend to have tall children to have tall children).But diet or nutrient availability affects how tall an organism actually grows. flagellum-genes determine if a microorganism can grow a flagellum but some will only strait to grow them in a certain environments eg if metal ions are present.

Question 33

what is the mean What shape is a normal distribution?

Answer 33

average of the values collected in a sample. mean=total of all the values in the data/no of the values in the data. it can be used to tell there if there is variation in samples. bell shaped curve-symmetrical ab the mean

Question 34

what's standard deviation What percentage of things in a normal distribution are within ,2 and 3 standard deviation of the mean? What features are the same in a normal distribution?

Answer 34

tells you how much the values in a single sample vary.measure of the spread of values about the mean. 68% of the data,95%,99.7% The mean, median, and mode are all equal and at the centre of the distribution. The curve is symmetrical about the mean. The shape of the curve is bell-shaped. The proportion of data within 1, 2, and 3 standard deviations is constant: 68%, 95%, 99.7%.

Question 35

explain this bell curve

Answer 35

page 271 diagram

Question 36

work out the standard deviation for this tree A-22 B-2 C-26 D-29

Question 37

what's the range and compare it to standard deviation

Answer 37

Diff between highest and lowest. SD is better than the range because it takes into account all the values in the data set whereas the range only uses 2 this makes the range more likely to be affected by an anomalous result than SD.

Question 38

how to work out correlation between a factor a variation in a particular characteristic

Answer 38

calculate spearmans rank correlation coefficient-it shows how and how strongly related. result is number between -1 and 1 if its -1 then its a perfect negative correlation between2 v and vice versa.the closer figure is to 0 the weaker the correlation is.

Question 39

example of spearmint rho

Question 40

what are adaptations

Answer 40

Not all organisms are built the same — variation within and between species means some are just better adapted to their environment than others. 👉 Being adapted = having features that boost your chances of survival and reproduction, and help your offspring reproduce too. These features = adaptations. They can be: Behavioural 🧠 Physiological ⚡ Anatomical 🦴 Adaptations exist because of evolution by natural selection. In every generation, the best-adapted individuals are more likely to survive, reproduce, and pass on their winning alleles to the next round. Survival of the fittest, literally.

Question 41

what are types of adaptations

Answer 41

Behavioural adaptations These are ways an organism acts that increase its chance of survival. Examples * Possums sometimes 'play dead' — if they're being threatened by a predator they play dead to escape attack. This increases their chance of survival. Scorpions dance before mating so they attract a mate if same species Inc likelihood of successful mating . Physiological adaptations These are processes inside an organism's body that increase its chance of survival. Brown bears hibernate — they lower their rate of metabolism (all the chemical reactions taking place in their body) over winter. This conserves energy, so they don't need to look for food in the months when it's scarce — increasing their chance of survival. Some bacteria produce antibiotics — these kill other species of bacteria in the area. This means there's less competition, so they're more likely to survive. Anatomical-These are structural features of an organism's body that increase its chance of survival. Example-Otters have a streamlined shape — making it easier to glide through the water. This makes it easier for them to catch prey and escape predators, increasing their chance of survival. Whales have a thick layer of blubber (fat) — this helps to keep them warm in the cold sea. This increases their chance of survival in places where their food is found.

Question 42

What is convergent evolution and give an example

Answer 42

Organisms from different taxonomic groups may have similar features even though they're not closely related - whales n sharks. = because the organisms have evolved in similar environments and to fill similar ecological niches. When 2 species evolve similar characteristics independently of one another because they've adapted to live in similar environments) it's called convergent evolution. There are eg of convergent evolution between the distantly-related marsupial and placental mammals.

Question 43

What are marsupial and placental mammals and how did they evolve?”

Answer 43

There are three different groups of mammals. Most are placental mammals, some are marsupials (and a very few are egg-laying monotremes). Marsupials are found mainly in Australia and the Americas. They diverged from placental mammals many millions of years ago and have been evolving separately ever since. There’s a few distinct differences between marsupial mammals and placental mammals

Question 44

How do marsupial and placental mammals differ?

Answer 44

Marsupial mammals-Have a short gestation period (pregnancy). Don't develop a full placenta. Are born early in their development and climb into their mother's pouch. Here they become attached to a teal and receive milk while they continue to develop. Placental mammals - Have a longer gestation period. Develop a placenta during pregnancy, Don't develop a full placenta. which allows the exchange oi nutrients and waste products between the fetus and the mother. Are born more fully developed.

Question 45

How have marsupial and placental moles evolved similarly?

Answer 45

Although marsupial and placental mammals have been evolving separately for years evolution of some species has converged There are many different species of mole. Most are placental moles, but there are also two species of marsupial mole. Marsupial and placental moles aren’t closely related but have evolved similar features independently (convergent evolution) because they live in similar environments. Both live underground in tunnels and burrow for food (e.g., earthworms, insects). adaptations for this: * Small or nonexistent eyes because they don't need to be able to see underground. * No external ears, to keep a streamlined head for burrowing. - Scoop-shaped and powerful front paws, which are good for digging. * Claws that are specialised for digging. * A tube shaped body and cone shaped head, which makes it easier to push through sand or soil.

Question 46

what were Darwins 4 observations

Answer 46

Organisms produce more offspring than survive. There's variation in the characteristics of members of the same species. Some of these characteristics can be passed on from one generation to the next Individuals that are best adapted to their environment are more likely to survive.

Question 47

what was darwins theory of natural selection

Answer 47

Individuals within a population show variation in their phenotypes (their characteristics). Selection pressures (environmental factors such as predation, disease and competition) create a struggle for survival. Individuals with better adaptations (characteristics that give a selective advantage, eg. being able to run away from predators faster) are more likely to survive and have reproductive success — in other words, they reproduce and pass on their advantageous adaptations to their offspring. Over time, the proportion of the population possessing the advantageous adaptations increases. Over generations this leads to evolution as the favourable adaptations become more common in the population.

Question 48

How Genetic Variation Drives Natural Selection.

Answer 48

Genes influence many characteristics, and individuals vary in phenotypes due to different alleles in gen variation.Organisms with advantageous traits are more likely to survive and pass these alleles to their offspring.”

Question 49

peppered moth example

Answer 49

show variation in colour — there are light ones (w alleles for light colour) and dark ones (w alleles for dark colour). * Before the 1800s there were more light moths than dark moths. * During the 1800s, pollution had blackened many of the trees that the moths lived on. * Dark coloured moths were now better adapted to this environment - they were better camouflaged from predators, so would be more likely to survive, reproduce and pass on the alleles for their dark colouring to their offspring. During this time the dark moths increased + the alleles for dark colour became more common in the population.

Question 50

Wallaces contribution

Answer 50

Alfred Russel Wallace independently developed the idea of natural selection and corresponded with Darwin. They published together, acknowledging each other’s work. — they didn't always agree about the mechanisms involved in natural selection. Wallace's provided lots of evidence to support the theory of evolution by natural selection. eg he realised that warning colours are used by some species (e.g. butterflies) to deter predators from eating them and that this was an eg of an advantageous adaptation that had evolved by natural selection.Darwin’s book On the Origin of Species later popularised the theory, which is why he is better remembered. he wrote about all the species that he had observed during his voyage to South America and the Galápagos Islands in the 1830s.

Question 51

Evidence to support evolution

Answer 51

Fossil Evidence: Fossils are the remains of organisms preserved in rocks. By arranging fossils in chronological order, gradual changes in organisms can be observed as evidence of evolution. Example: Horse fossils show a gradual increase in size, lengthening, and hoof development over time. Molecular Evidence: The theory of evolution suggests that all organisms have evolved from shared common ancestors. Closely related species diverged (evolved into different species) more recently. Evolution is caused by gradual changes in the base sequence of organisms’ DNA. Organisms that diverged more recently have more similar DNA because less time has passed for changes to accumulate. This has been confirmed by scientists. Example: Humans, chimps, and mice all evolved from a common ancestor. Humans and mice diverged a long time ago, while humans and chimps diverged more recently. Human and chimp DNA is 94% the same, but human and mouse DNA is only 85% the same. Molecular Evidence – Proteins and Other Molecules: In addition to DNA, similarities in other molecules also provide evidence for evolution. Scientists compare the sequence of amino acids in proteins and antibodies. Organisms that diverged more recently have more similar molecules because fewer changes have occurred over time.

Question 52

How does natural selection lead to pesticide resistance in insects?”

Answer 52

Pesticides are chemicals that kill pests (e.g. insects that damage crops), species of insect. Scientists have observed the evolution of pesticide resistance in many Examples -Some populations of mosquito have evolved resistance to the pesticide DDT.

Question 53

How Natural Selection acc works in Pesticide Resistance n example of resistance to DTT?

Answer 53

1.There is variation in a population of insects. Genetic mutations can make some insects naturally resistant to a pesticide. 2.If the population is exposed to that pesticide, only the individuals with resistance survive to reproduce. 3.The alleles that cause pesticide resistance are passed on to the next generation. 4.Over many generations, the population evolves to become more resistant to the chemical. Tip: Mutations are changes to the DNA base sequence. They can produce new alleles, such as alleles for pesticide resistance. Example – DDT was first used to kill malaria around WWII. By the 1950s, some mosquitoes had mutations giving them an allele for DDT resistance. When exposed, non-resistant mosquitoes died, while resistant ones survived, reproduced, and passed on the allele. Over generations, DDT resistance became widespread in these populations

Question 54

Implications of pesticide resistance for humans

Answer 54

Crop infestations with pesticide-resistant insects are harder to control. Some insects are resistant to multiple pesticides, making it difficult for farmers to find an effective chemical in time to prevent crop damage. If insects are resistant to specific pesticides, farmers may need to use broad-spectrum pesticides, which can also kill beneficial insects. Disease-carrying insects, such as mosquitoes, becoming resistant could increase the spread of disease. Insects could eventually evolve resistance to all pesticides in use, requiring the development of new pesticides, which is time-consuming and costly.

Question 55

Evolution of Antibiotic and Drug Resistance”

Answer 55

scientists have observed h evolution of antibiotic resistance in many species of bacteria, e.g. MRSA. Other pathogens have evolved resistance to specific drugs too. Example - to treat malaria. Some of the protoctists that cause malaria are resistant to several drugs used

Question 56

Implications of drug resistance to humans

Answer 56

Infections caused by drug-resistant microorganisms are harder to treat — especially if the microorganism is resistant to lots of different drugs. I can take doctors a while to figure out which drugs will get rid of the infection, and in that time the patient could become very ill or die. There could come a point where a pathogen has become resistant to all the drugs we currently use against it. To prevent this, new drugs need to be developed. This takes time and costs a lot of money.