Semester 1 Exam Flashcards

The Universe

• All of matter and energy that exists in space and time

• It is everything that has ever existed and everything that ever will exist

Stars

• Giant spheres made of super heated gas

• Produce energy through nuclear fusion

Planets

• Spheres made of matter that orbit stars

Black holes

• Massive stars that end their lives by collapsing in on themselves

• So dense and have such a strong gravitational field that light can’t escape

Nebulas

• Made of hydrogen gas and dust

• Slowly collapse together under the force of gravity to create stars

• Leftover gas and dust forms planets (a nursery)

Galaxies

• Collection of stars, stellar remnants, gas, dust and dark matter

• Held together by gravity

Astronomical unit & when to use

• Average distance between Earth and the Sun

• Measures distances in our Solar System

Light year & when to use

• Distance light travels in a year

• Measures dinstances to other stars in the Milky Way

Parsec & when to use

• Measures distances to other galaxies

Wurdi Youang stone arrangment

• Located in Ballarat, Vic

• Over 11’000 years old - oldest known astronomical site

• Maps different setting positions of the sun throughout the year

• Shows different seasons & what food is available

Electromagnetic waves

• Form of radiation

• Travels through vaccum of space at the speed of light

• 7 types

Main sequence

• First stage after creation

• Composed of 98% hydrogen and helium

• Lasts 90% of Star’s life

Supergiant

• Produce heavier elements like Iron through fusion

• Makes them lose mass

Supernova

• Outer layers are of H and He are ejected

• Happens within seconds

Neutron star

• Core collapses into a dense mass of neutrons

Life cycle of high mass stars

1. Stellar nebula

2. Protostar

3. Main sequence

4. Supergiant

5. Supernova

6. Black hole or Neutron star

Red giant

• Star extends the outer layers by using the H in the core

• Grows more than 100x their main sequence size

Planetary nebula

• Outer layers are ejected

• Core contracts into a white dwarf

• Takes tens of thousands of years

White dwarf

• Composed of carbon and oxygen

• Can also be neon, magnesium and helium

Black dwarf

• Theoretical phase

• Occurs when the Star has cooled so much it no longer emits light

• Universe’s existense is too short to prove this

Life cycle of low mass stars

1. Stellar nebula

2. Protostar

3. Main sequence

4. Red giant

5. Planetary nebula

6. White dwarf

7. Black dwarf

Exoplanet

• Planet that orbits a star outside our solar system

Criteria of a Planet

1. Be spherical

2. Orbit a star

3. Big enough that its gravity clears away things in its orbital path

Criteria for life to form

• Liquid water must be able to form

• Only occurs in “Goldilocks zone’s”

Elliptical galaxies

• Spherical/egg shaped

• Lack gas and dust

• Therefore cannot form new stars

• Do not rotate

Spiral galaxies

• Have a buldge made of stars

• Rotate and therefore have “arms”

• Mix of young and old stars

• Bars can form if stars orbit becomes unstable - stretches out and grows as they collect new stars

Irregular galaxies

• No symmetry/organised structure

• Mix of young and old stars

• Have pockets of gas

Steady state theory

Suggests:

• Density of the universe is infinite

• Universe only expands as new matter is created

• Constant creation of matter keeps the universe in a steady state

• In theory, properties of the universe do not change; has no beginning or end of time

The Big Bang Theory

• The universe was once in a condition where density is infinite

• Was very hot & expanded rapidly creating the big bang

• The rapid expansion cooled and the universe became what it is today

• Homogenous and uniform in all directions of space, but not time

Cosmic background radiation

• Uniformly fills the universe

• Supports big bang theory; provides evidence of the universe’s early hot and dense state

Creation of the Universe

1. Big bang

2. Inflation

3. First protons and neutrons created

4. First Helium and Hydrogen atoms created

5. Light shines for the first time

6. Stars and galaxies form

7. The Solar System forms

8. Earth forms

9. Life starts to appear on Earth

Excited state

• Occurs when an atom gains energy and jumps to a higher valence shell/energy level

• Unstable state

• Will eventually lose energy in the form of light and moves back down to its original shell

Group numbers

• Number of electrons in the valence shell

Period numbers

• Number of valence shells

Metals

• Lustrous

• Malleable

• Ductile

• Good conductors of heat and electricity

• 1-3 valence electrons

Non-metals

• Non shiny or lustrous

• Poor conductors of heat and electricity

• 4-7 valence electrons

Metalloids

• Brittle

• Somewhat shiny

• Semiconductors

• 3-6 valence electrons

Cation

Positively charged atom

Anion

Negatively charged ion

Ionic bonding

• Between a metal and a nonmetal

• Atoms will gain or lose electron/s to become stable

• Electrostatic attraction between the atoms ionically bonds the two together

Covalent bonding

• Between nonmetals

• Atoms share electrons to form an intramolecular bond

Metallic bonding

• Between metals

• Electrons are delocalised and free to move throughout the metal lattice; creates a “sea of electrons”

• Holds metals togeter

Intramolecular bond

• Bond within molecules

• Strong

Intermolecular bond

• Bond between molecules

• Weak

Amino Acids

• Human body uses 20

• Joined together by a chemical reaction to form polymer

• 50 amino acids joined together forms a protein

Proteins

• Transmit messages

• Build structures

• Perform chemical reactions

• Support the immune system

• Store vital chemicals for the body like amino acids

Proteins & amino acids; link to the big question

Murchison meteorite:

• Fell in Victoria in 1969

• Contained amino acids such as;

  • Glycine

  • Alanine

  • Glutamic acid

  • & unidentified acids

Asteroids:

• Amino acids have been found on asteroids 200 million miles from Earth

Link to BQ:

• Amino acids form proteins

• Proteins are building blocks of cells which can form living substances

• Also perform functions that maintain life

Biological evolution

• Genetic change in a population

• Inherited over several generations

LUCA

• Last Universal Common Ancestor

• Original form of life

• Most likely a prokaryotic cell

• Lived near iron rich, underwater hydrothermal vents

• Around 3 billion years ago LUCA evolved to photosynthesise

• After this, oxygen started to accumulate in the atmosphere

Brief timeline of the evolution of Homo sapies

• 3.7 billion years ago - single cellular organisms exist

• 800 million years ago - multicellular organisms exist

• 4 million years ago - first humans exist

• 70’000 years ago - Homo sapiens exist

Biodiversity

• The variety of livings things and their interactions with their environment

• Changes over time as a result of evolution

Levels of Biodiversity

1. Species: the number of species present in an ecosystem

2. Genetic: genetic variation within the species

3. Ecosystem: the variety of habitats, ecosystems and communities

Key observations of Darwin’s Theory of Evolution

1. Traits are inheritable

2. More offspring are produced than can survive

3. Offspring vary in their inherited traits

Natural selection

• Natural mechanism of evolution

• Organisms that are better adapted to the environment through inherited traits have a better chance at survival

• Therefore, these traits are passed down to the next generation

• Depends on the environment

• Acts on existing variation in the animal - must be variation in the species to occur

Key points of evolution

1. Variation: must be genetic differences in the population

2. Birth rate: more offspring are produced than can survive

3. Inheritance: the trait must be coded into the DNA for the organism to receive it

4. Selection: some organisms’ traits are more favorable, meaning the organisms that have are more likely to survive and pass those traits to their offspring

5. Time: the frequency of traits will change over time

Artificial selection

• Process of humans identifying desirable traits in animals and plants

• Then bred together to create a new organism

Process of artificial selection

• Observivng individuals in the population

• Selecting the individuals with the desirable traits

• Breeding the organisms together to create a new generation

• Repeating the cycle until the desirable organism is created

Negative side effects of artificial selection

• Defects and less genetic diversity

• New diseases

• No contronl over genetic mutations

Species

• A group of living organisms consisting of similar individuals that are capable of breeding

Speciation

• Process of forming new and distinct species over evolutionary time

• Occurs in 4 stages

Stages of speciation

• Variation: must be genetic differences in the population

• Isolation: an event occurs in which are part of the population is isolated

• Selection: the usual process of natural selection occurs

• Time: over thousands of years, the two populations have changes so much that they can no longer breed and are difference species

The fossil record

• Shows history of life as documented by fossils

• Incomplete due to the conditions required for fossils to form

Formation of fossils

• Organism must be covered with sediment very close to time of death

• The rocks the organism is covered with must be burried as well so the organism is preserved, but eroded enough so that the fossil can be found

Pertrification

• Occurs through permineralisation

• After the organism is burried in sediment, it may be exposed to mineral rich fluids that flow through the rocks

• Rocks are filled with preserving minerals like calcium carbonate and silica

• Minerals replace the organic materials and the remains are turned to stone

Compression

• An imprint of the fossil is produced

• Due to high pressures from the weight above

Moulds and casts

• If the shell or bone dissolves, it can leave a space in the shape (mould)

• Sediments fill the space to form a cast

Preserved remains

• Organisms beome trapped in amber, preserving the organism

Comparative anatomy

• Study of the similarities and differences in the structures of different species

Divergent evolution

• Two or more species diverge from a common ancestor

• Evolve seperately due to different selection pressures

Homologous structures

• Similar structures in related organisms

• Due to inheritance from common ancestors

• Structures have differing functions

Convergent evolution

• Two or more organisms evolve in similar environmet, and therefore have similar characteristics

• Due to selection pressures

Analogous structures

• Similar structures in unrelated organisms

• Evolve to do the same job, not due to inheritance

Genome

• All of an organisms DNA and the way it is stored and structured

Comparative genomics

• Study of comparing genomes for similarities in the DNA sequence

• The more similar, the more related

Evidence for LUCA

• All living organisms have the same 4 bases in their genetic codes

• Same mechanisms for turning DNA into proteins

Homologous gene

• Genes that have a similar function

• Passed down from a common ancestor

Ubiquitious proteins

• Proteins that exist in many living things

• Performs the same function in each

Number of Protons =

= atomic number

Number of electrons =

= number of protons (neutral atom)

Neutrons =

= mass number - protons

Mass number =

= protons + neutrons

Element+ =

= - electrons

Element- =

= + electrons

Neutral charge =

= same number of protons and electrons

Negative charge =

= more electrons than protons

Positive charge =

= more protons than electrons