Life's basics Flashcards
steps of the scientific method
- observation
- hypothesis
- new observations or experiments
- develop a theory
observation
Recorded as data - quantitative or qualitative
Microscopes, precision instruments etc.
Use statistics to determine if data is significant or random fluctuations
Inductive reasoning - generalisations derived from a large number of specific observations eg. The sun always rises in the east
hypothesis
possible explanations from observations that lead to a testable prediction
Can carry out an experiment (test under controlled conditions)
Deductive reasoning: “if”…”then” logic that flows on from premises.
Can never be proven true
Validity is increased when many scientists test the hypothesis and it stands up to experimentation
Predictions (based on hypothesis)
new observations or experiment
to test hypothesis
If results are not consistent, reject or revise hypothesis
If there is a change, hypothesis is correct (not necessarily correct) - come up with a new prediction to check again
develop a theory
when multiple related hypothesis have been supported, it is a theory.
Broader than a hypothesis
Vast amount of evidence
Can be modified or rejected
model organism
a species that is easy to grow in a lab and can be experimented upon (all living things are evolutionary connected).
what are the two types of studies?
observation and experimentation
experimentation
Test 2 or more groups in controlled conditions (truly assess impact of one variable - IV)
IV
what you change (in the experimental group)
DV
what you measure
controlled variable
variables you keep the same - species of flower, height of flower so that only colour is tested
control group
without the IV to determine whether other factors (other than the IV) cause the change
graphs
x axis: independent variable eg. Colour of flower
Y axis: dependant variable eg. Average time spent at each flower
sexual dimorphism
males and females of the same species display different characteristics other than genitalia.
facts about widow birds and their sexual dimorphism
From Africa
Female: yellow-brown, plain looking (blends into grasses)
Males: long black tails and red wings, white shoulders
Males jump with fluffed feathers to attract females - highest and longest
Males compete to be most impressive
Female lays eggs in one of the many nests in the male’s territory
characteristics of living things
- complex with precise spatial organisation
- change in response to environment
- can reproduce to pass on genetic info
- evolve
- metabolism
define evolving
changing over generations in response to environmental pressure.
what is homeostasis
maintaining a stable internal environment in the face of changing external environments
what is ecology?
the study of how organisms interact with one another and their natural environment.
Trees requiring bees to pollinate them to produce a seed
The seed is eaten and taken away so that it can grow somewhere where it will not have to compete with the other tree
Evolution allowed for the selection of sweeter flowers and sweeter fruits so that the animals want them
first law of thermodynamics
Energy can neither be created nor destroyed; it can only be transformed from one form into another.
Total energy in the world is constant
Living things transform energy from the sun or chemical compounds - inputs and outputs
Move, reproduce, build cellular components etc.
Dissipated as heat
second law of thermodynamics
The degree of disorder (or the number of possible positions and motions of molecules) in the universe tends to increase.
Organising marbles into a row takes energy, so does organising a cell
Entropy: the amount of disorder in a system.
Some energy is used for organising the cell but the rest is released as heat.
Heat increases motion and therefore increases disorder - by releasing heat, cells keep with the second law
Entropy can decrease locally (in the cell) when heat released into the environment increases disorder outside.
the cell - definition and features
Cell: simplest entity that can exist as an independent unit of life- simplest form of life.
Every living thing is made of cells - one, to a few to many
Vary in size
Cells have a stable blueprint, a boundary between the outer environment and an ability to harness materials and energy from the environment
Three main features of cells - store and transfer genetic info, enclosed in a membrane and undergoes metabolism
what are nucleic acids?
Nucleic acids store and transmit information needed to grow, function and reproduce
Acts as a blueprint
Cells copy this information to reproduce
DNA
a type of nucleic acid Double stranded helix
Each stand is a varying sequence of four different molecules, connected end to end
This sequence encodes cellular info
Directs the formation of proteins - structural and functional molecule involved in shape, movement, chemical reactions etc.
DNA is replicated and passed onto progeny - mistakes can be lethal
Mutations: changes to DNA that arise in replication of from environmental impacts. They can be lethal or lead to variation and evolution.
RNA
- a type of nucleic acid
Single stranded
Proteins copy the DNA template strands into a different form (mRNA)
Transcription: copying the information and forming mRNA
Translation: specialised proteins read the mRNA strand and assemble a protein
what is the central dogma?
pathway from DNA to RNA to proteins
what is a gene?
a section of DNA sequence that corresponds to a specific protein
what is the plasma membrane and what does it do?
separates the living interior of a cell from its non-living environment
Controls movement of materials into and out of the cell (protects the cell)
Selectively permeable
Membranes also surround internal structures (organelles), compartmentalising