Topic 1,2,3 bio 1020

what is biology

what is biology

the scientific study of life

what is life

an imperfect replicating system that evolves by natural selection

the basic properties of life

1. life is ordered

2. life uses energy

3. life undergoes growth and development

4. life responds to its environment

5. life regulates itself

6. life reproduces

7. life adapts by evolutionary adaptation

describe-life is ordered

• organized into highly ordered structures

• energy must be put into the system to maintain order

• non living things can be ordered, but less than living things (crystalline structure of minerals)

describe-life uses energy

• maintenance of order

• reproduction

• movement in the environment

• obtaining food and resources for growth and development

describe-life undergoes growth and development

• DNA is inherited and controls the pattern of growth and development through the regulation of gene expression

describe-life responds to its environment

• constant monitoring of its environment

• predator avoidance

• changing diet according to season

• tilting leaves and flowers towards the light

• regulating internal conditons

• temperature

describe-life regulates itself

• homeostasis is the steady state regulation of the organism

• often a response to environment

• flow of blood through your vessels

describe-life reproduces

• the need to make more of its own kind

• asexual and sexual modes of reproduction

• cloning, fragmentation, budding, sex

describe-life adapts by evolutionary adaptation

• populations of species adapt to their environment by evolution

• the environment selects against individuals that are not suited to the environment via natural selection

arrange the levels of biological organization in their proper order

1. the biosphere - consists of all life on earth contained within all the ecosystems

2. ecosystems - all living things + non living within a particular area

3. communities - assemblages of different populations of different species living close together with the potential to interact

4. populations - group of interbreeding individuals of the same species that live in the same area

5. organisms - individual living things

6. organs - a collection of different tissues with a specialized function

7. tissues - a collection of differentiated, specialized cells

8. cells - a collection of organelles within a membrane

9. organelles - a collection of molecules form organelles (in eukaryotes)

10. molecules

what is a virus

• dna/rna is surrounded by a capsid

• when a cell is infected, the virus releases its genetic material which hijacks the cell into producing more viruses

are viruses living

no because they don’t meet all the 7 criteria of living organisms

eukaryotes

• use dna as genetic code

• one domain - eukarya

• have a nucleus and other internal compartments

• single celled or multicellular - humans

prokaryotes

• two domains - bacteria and archaea

• use dna as genetic code

• no nucleus

• always single celled

describe how energy flows through an ecosystem while nutrients cycle within it

energy is transformed from the sun by photosynthesis and transformed again in cellular respiration. energy is transferred to metabolic processes and food chains. the energy is then lost as heat in the ecosystem.

plants take up chemicals from the soil and air, the chemicals in the plants will then be passed to organisms that eat the plants. energy is then returned to the soil via decomposition by fungi and bacteria

list the 3 domains of life

• bacteria - prokaryote

• archaea - prokaryote

• eukaryotes

phylogenetic trees

represent hypothesis about the evolutionary relationship of the organism - usually based on DNA/genetic relationships

arrange the taxa in their proper Linnaean hierarchy

King Philip Cried Out, ‘For Goodness Sake’

kingdom, phylum, class, order, family, genus, species

hypothesis

a proposed explanation based on observations and assumptions that is testable

• an explanation that is broader in scope than a hypothesis, generates new hypotheses

theory

is supported by a large body of evidence

• there is one theory in biology: cel theory (cells are fundamental unit of structure in living things) (supported by many independent hypotheses and observations)

inductive reasoning

type of logic in which generalizations are based on large number of observations

deductive reasoning

logic that flows in the opposite direction, so from general to specific

• takes on IF and THEN

cause

factor A leads to condition B

• low temperatures cause leaf colour change

• if i study, i will do well in my class

correlation

when factor A changes, so does condition B

• heart rate increases with increased physical activity

• can be actual or meaningless

outline the requirements for natural selection

• organisms have variable traits that make them unique (phenotype)

• the traits must be variable within the population

• the traits must be passed on from parent to offspring (heritable)

• natural selection acts on these traits (evolutionary adaptation)

selective pressure

• favourable traits are selected for and passed onto the next generation

• unfavourable traits are selected against and not passed on

evolution

descent with modification

aristotle

saw species as unchanging, or fixed

• scala naturae

• basis of old testament

carl linnaeus

classified life according to their similarities

• linnaean classification of taxonomy

• described based on pattern of their creation

georges cuvier

noted older strata had different species that newer strata

• speculated that each stratum represented a single catastrophic event leading to the extinction of that species

james hutton

proposed that earth’s geological features were a result of gradual processes (erosion, valleys being formed by rivers)

charles lyell

proposed the same geological process in the past were occurring in the present, at the same rate

jean baptiste lamarck

proposed the first hypothesized mechanism for evolution

• suggested that evolutionary change explains the patterns seen in the fossils and how certain organisms are found in certain environments

• suggested there were multiple lines of descent (older to newer fossils)

• suggested it was explained by use and disuse

• inheritance of acquired characteristics

adaptive radiation

a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms

• when a change in the environment makes new resources available, creates new challenges or opens new environmental niches

phylogenetic trees

• depicted are the evolutionary relationships of vertabrates

• all organisms have been evolving for the same amount of time

• diverging from previous ancestor every time

artificial selection

modifying other species by selecting and breeding individuals with desired traits

relative fitness

contribution an individual makes to the gene pool of the next generation relative to other individuals in that population

traits that can lead to relative fitness

• not having a genetic disorder

• not getting eaten by a predator

• not getting a disease

• surviving environment conditions

• accumulating nutrients

• ability to attract a mate

vestigial structures

had a function in a past ancestral species, but is no longer useful today

• tailbones

homologies

features that have underlying similarity but different functions

homologous structures

can have similar structures, different functions due to selection for those functions over time

divergent evolution

structures adapt by natural selection to do different functions (diverged into different structures)

analogous structures

similar function, different structure

convergent evolution

unrelated species that develop similar characteristics over time

genetic drift

the change in frequency of an existing gene variant in the population due to random chance

gene flow

the transfer of genetic material from one population to another (movement of genes)

relative fitness

the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

directional selection

shifts the overall makeup of the population by favouring variants that are at one extreme of the phenotypic distribution

• light mice selected against

disruptive selection

favours variants at both ends of the phenotypic extreme

• intermediate colour selected against

stabilising selection

removes the extreme phenotypic variants from the population and preserves the intermediate types

• light mice and dark mice selected against

sexual selection

individuals with certain inherited traits are more likely that others to obtain mates

intrasexual selection

selection within the same sex where individuals compete directly for mates of the opposite sex

intersexual selection

“mate choice” individuals in one sex are choosy in selecting mates

balancing selection

maintains two or more phenotypic forms in a population

frequency dependent selection

the fitness of a phenotypic depends on how common it is in the population

heterozygote advantage

heterozygous individuals have greater relative fitness than either of the homozygous individuals

• sickle cell

• malaria

conditions on early earth made life possible

1. the abiotic synthesis of small molecules, such as amino acids and nitrogenous bases

2. the joining of these molecules into macromolecules, such as proteins and nucleotides

3. the packaging of these molecules into protocells (first cells)

4. the origin of self replicating molecules that eventually made inheritance possible

geological record

standard scale of time that divides earth’s history into four eons and further subdivisions

mass extinctions

results in the loss of many species over a large expanse in a short amount of time

• there have been 5 mass extinctions

consequences of mass extinctions

• reduce a larger number of species

• reduce a complex ecological community to a shell

• species cannot reappear

adaptive radiations (benefits of mass extinction)

groups of organisms form many new species in relatively short time and whose adaptations can enable them to survive in environments their ancestors couldn’t

elements

cannot be broken down to smaller substances

92 natural elements 20 man made

compounds

contains 2 or more elements in fixed ratios

atoms

smallest unit of life

neutrons - neutral

electrons - negative charge

protons - positive charge

atomic mass

the sum of the protons and neutrons in the atomic nucleus

atomic number

is the number of protons in the atom

each element has a unique number of protons within its atoms

isotopes

same number of protons, different number of neutrons

stables isotopes do not lose subatomic particles

radioactive isotopes release subatomic particles and energy as the nucleus decays

carbon has __ naturally occurring isotopes

carbon 12- stable, most common 6 protons 6 neutrons 99% of all carbon

carbon 13- stable 7 neutrons 6 protons

carbon 14-unstable/radioactive 6 protons 8 neutrons

electron shells

orbitals that surround the nucleus

depicted as rings

1st shell 2 electrons 1s orbital

2nd shell 8 electrons 2s orbitals 2p orbitals

s=sphere

p=peanut

valence electron

the outermost, unused electrons

valence shell

outermost electron shell

ionic bonds

transfer electrons

formed between ions to fill valence shell

cations - positive

anion - negative

covalent bond

result from sharing electrons

molecules

two or more atoms held together by covalent bonds

polarity

difference in charge

electronegativity

the attraction of a particular atom’s electrons in a covalent bond

non polar covalent bond

the electrons are shared equally(due to the same electronegativity)

polar covalent bond

the electrons are shared unequally due to one atom being more electronegative than the other

most electronegative element

oxygen

hydrogen bonds

a weak chemical interaction

hydrogen is covalently bonded to an electronegative atom

van der waals interactions

weak interactions between molecules that have varying partial charges

interactions between foot molecules and wall molecules allow geckos to climb vertical walls

what do chemical reactions

change the composition of matter by making or breaking chemical bonds

when is chemical equilibrium achieved

when the forward and reverse rates ares the same

hydrogen ion

hydroxide ion

hydronium ion

H+ a single proton

OH- a water molecule that lost a proton

H3O+ water molecule that gains a proton

which is more electronegative, oxygen or hydrogen

oxygen, bonds between oxygen and hydrogen are polar covalent within a single water molecule

water molecules are held together by hydrogen bonds

water molecules can stay together

cohesion: the linking together of the water molecules via hydrogen bonding

• results in surface tension, a measure of how hard it is to break/stretch the surface of a liquid

adhesion: the clinging together of one substance to another

high specific capacity

the amount of heat that must be absorbed or lost to change the temperature of 1g of substance by 1C

water moderates temperature

warms the air at night, cools during day

water stabilizes ocean temperatures making favourable environments

solid water is less dense than liquid water

ice floats

water molecules expand as the freeze

more air pockets, less dense

water is the solvent of life

solutions

are homogenous mixtures of two or more substances

solvent

does the dissolving

solute

is the thing being dissolved

aqueous solutions

solutions made by dissolving solutes in water

hydrophobic

repels water

hyrdophilic

water loving

concentration

the number of moles of solute per litre of solution

acid

increases the hydrogen concentration of a solution H+ goes up

acids dissolve in water

dissociates to release hydrogen ions

base

reduces the hydrogen concentration of a solution OH- goes up

bases dissolve in water

lowers concentration by:accepting hydrogen ions, dissociating to produce excess hydrogen ions

pH scale

measures the logarithmic concentration of hydrogen ions