Classification

Question 1

What is classification

Answer 1

The act of arranging organisms into groups based on their similarities and differences. This makes it easier for scientists to study them.

Question 2

How many taxonomic levels are there

Answer 2

8

Question 3

What are the 8 taxonomic groups

Answer 3

1) domain
2) kingdom
3) phylum
4) class
5) order
6) family
7) genus
8) species

Question 4

The five kingdom classification system and their general characteristics

Answer 4

Prokaryotae- bacteria - prokaryotic , unicellular, no nucleus, less than 5 micrometres

Protoctista - algae and Protozoa- eukaryotic cells, usually live in water, single celled or simple multicellular organisms

Fungi - moulds, yeast mushrooms- eukaryotic, chitin cell wall, saprotrophic, single/multi cellular

Plantae- mosses, ferns, flowering plants - eukaryotic, multicellular, cell walls made of cellulose, can photosynthesises, contain chlorophyll, autotrophic.

Animalia- mammals, birds, fish , insects - eukaryotic, multicellular, no cell walls, heterotrophic.

Question 5

What is a saprotrophic organism

Answer 5

An organism that absorbs substances from dead or decaying organisms

Question 6

What is the naming system used in classification

Answer 6

It is called the binomial system. The first part is the genus name and has a capital letter. The second part is the species name and begins with a lower case. Always written in italics unless handwritten then they are underlined.

Question 7

What is phylogeny

Answer 7

The Study of the evolutionary history of groups of organisms

Question 8

How to show relationships between organisms

Answer 8

Phylogenetic tree. Branches show common ancestors

Question 9

What is it called when you classify organisms into groups and take phylogeny into account

Answer 9

Cladistics

Question 10

Why is observable features not enough to place organisms into groups

Answer 10

Scientists do no always agree on the relative importance of different features and groups based solely on physical features may Not show How related organisms Are.

Question 11

Other evidence that shows how similar organisms are

Answer 11

1) molecular evidence - the similarities in proteins and DNA. You can compare things like how DNA is stored and the sequence of DNA bases. You can also compare the sequence of amino acids in proteins.

2) embryological evidence- the similarities in the early stages of an organisms development

3) Anatomical evidence - the similarities in structure and function of different body parts.

4) behavioural evidence - the similarities in behaviour and social organisation of organisms.

Question 12

What is the three domain system.

Answer 12

In 1990, the three domain system replaced the older five kingdom system. The three domains were Eukarya, Archaea and Bacteria. Domains was the highest taxonomic level and the lower hierarchy stays the same.

Question 13

Evidence that led to the proposal of the three domain system

Answer 13

1) molecular evidence - the enzyme RNA ploymerase is different in bacteria and Archaea. Archaea but not bacteria have similar histones to Eukarya.

2) cell membrane evidence- the bonds of the lipids in the cell membrane of bacteria and Archaea are different. The development and composition of flagellae are also different.

Most scientists agree bacteria and archaea developed seperately and archaea is more closely related to Eukarya than bacteria.

Question 14

Variation definition

Answer 14

The differences that exists between individuals.

Question 15

Types of variation

Answer 15

1) intraspecific- occurs within a species
2) interspefific - occurs between species
3) continuous (no distinct categories) eg height
4) discontinuous (distinct categories ) eg blood type

Question 16

What can variation be caused by

Answer 16

1) genetic factors
2) environmental factors
3) both

Question 17

How do genetics cause variation

Answer 17

Different species have different genes. Individuals of the same species have the same genes but different alleles. The genes and alleles make up the organism’s genotype. Differences in genotype result in variation in phenotype.

Variation only caused by genetics includes blood Type in humans and antibiotic resistance in bacteria. Genetic factors are inherited.

Question 18

How does the environment cause variation

Answer 18

Differences in climate, Food and lifestyle can cause variation. Examples of variation caused by only environmental factors includes accents and whether people have pierced ears.

Question 19

How do both genetic and environmental factors cause variation

Answer 19

1) height- genes determine how tall an organism can grow but diet and nutrient availability affects how tall an organism actually grows.

2) flagellum - genes determine if microorganisms can grow a flagellum but some will only start to grow them in certain environments eg if metal ions are present.

Question 20

How can you compare variation between samples

Answer 20

By calculating means of different samples and comparing using a distribution curve.

Question 21

How can you tell variation within a sample

Answer 21

Standard devaition tells us the spread of values about the mean.

Question 22

How do adaptations make an organism better suited to their environment

Answer 22

1) being adopted to an environment means the organism has features that increase its chance of survival and reproduction, and the chances of its offspring reproducing successfully. Adaptations can be behavioural, physiological and anatomical. Adaptations develop by evolution by natural selection.

Question 23

What are some behavioural adaptations

Answer 23

This is when the way an organism Acts increases its chance of survival. For example:

1) possums sometimes “play dead” when threatened by a predator.

2) scorpions dance before mating to make sure they attract a mate of the same species.

Question 24

What are some physiological adaptations

Answer 24

These are the processes inside an organism’s body that increase its chance of survival. For example:

1) brown bears hibernate- they lower their rate of metabolism over winter. This conserves Energy so they don’t need to look for Food when it’s scarce.

2) some bacteria produce antibiotics. These kill other bacteria in the area so there is less competition and they are more likely to survive.

Question 25

What are some anatomical adaptations

Answer 25

These are structural features of an organism’s body that increase its chance of survival. For example:

1) otters have a streamlined shape making it easier to glide through water. This makes it easier for them to catch prey and escape predators.

2) whales have a thick layer of blubber which keeps them warm in the cold sea.

Question 26

How can different taxonomic groups have similar features

Answer 26

Some organisms from different taxonomic groups have similar features though they are not closely related eg whales and sharks. This is because they have evolved in similar environments and to fill similar ecological niches.

Question 27

How are marsupial and placental mammals different

Answer 27

1) marsupial mammals have a shorter gestation period (pregnancy)
2) marsupial mammals don’t develop a full placenta but placental mammals develop placenta during pregnancy for exchange of nutrients between the Fetus and mother.
3) marsupial mammals are born early in their development but placental mammals are born more fully developed.

Question 28

Example of organisms that look similar but have different taxonomic groups.

Answer 28

Marsupial moles and placental moles aren’t closely related. They evolved independently on different continents. They do share similar anatomical features because they’ve high evolved to live in similar environments.

Both moles live in tunnels underground. They burrow to reach their Food supply. Their adaptations to this lifestyle include:
- small/nonexistent eyes because they don’t need to see underground
- no external ears to keep streamlined head for burrowing
- scoop shaped and powerful front paws for digging
- a tube shaped body ans cone shaped head which makes it easier to push through sand/soil.

Question 29

When did Darwin publish his theory of evolution by natural selection

Answer 29

1859

Question 30

What were Darwin’s key observations

Answer 30

1) organisms produce more offspring than survive.
2) there’s variation in the characteristics of members of the same species
3) some of these characteristics can be passed on from one generation to the next
4) individuals best adapted to their environment were more likely to survive.

Question 31

Darwin’s theory of evolution by natural selection

Answer 31

1) individuals within a population show variation within their phenotypes
2) selection pressure (eg predation, disease and competition) creates a struggle for survival
3) individuals with better adaptations are more likely to survive and reproduce, passing on their advantageous adaptations to their offspring.
4) over time the proportion of the population possessing the advantageous adaptations increases.
5) over generations, this leads to solution As the favourable characteristics become more common in the population.

Question 32

Wallace’s contribution to the theory of evolution

Answer 32

• he independently came up with the idea of natural selection and wrote to Darwin about it.
• he and Darwin published their papers on evolution together and acknowledged each other’s work.
• Wallace’s observations provided lots of evidence to support the theory of evolution by natural selection , for example, he realised that warning colours are used by some species (eg butterflies) to deter predators from eating them.

Question 33

Evidence to support evolution

Answer 33

1) fossil evidence. By arranging fossils in chronological order, gradual changes in organisms can be observed.

2) DNA evidence. Evolution is caused by the gradual changes in the base sequence of an organism’s DNA. Organisms that have diverged from each other more recently , should have more similar DNA.

3) Molecular evidence. They compare the sequence of amino acids in proteins and compare antibodies. Organisms that have diverged more recently have more similar molecules, and less time has passed for there to be a change in proteins.

Question 34

How have pests become resistant to pesticides.

Answer 34

1) there is a variation in a population of insects. Genetic mutations create alleles that make insects naturally resistant to a pesticide.

2) if insects are exposed to that pesticide, those with resistance will survive and reproduce.

3) the alleles that cause resistance will then be passed on to the next generation, so the population will evolve.

Question 35

How will pesticide resistance affect humans

Answer 35

1) crop infestations with pesticide resistant insects are harder to control. This means that before they find a pesticide that will kill the insects, the crops may be destroyed.

2) if disease carrying insects become pesticide resistant, the spread of disease could increase.

3) a population of insects could evolve resistance to all pesticides in use. To prevent this new pesticides need to be produced. This takes time and costs money.

Question 36

How does drug resistance affect humans

Answer 36

1) infections caused by drug-resistant microorganisms are harder to treat, it 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 I’ll and die.

2) there could be a point where the pathigens becomes resistant to all drugs we currently use. To prevent this, new drugs have to be developed. This takes time and costs money.