Y10 SEM1: SCI EXAM

physics, biology

Time

s, scalar

Distance

m, scalar

Displacement

m, vector

Speed

m/s, scalar

Velocity

m/s, vector

Acceleration

m/s², vector

Force

N, vector

Volume

L, scalar

km/h → m/s

divide by 3.6

m/s → km/h

multiply by 3.6

Newton’s First Law

Object stays at rest or constant motion unless acted on by an external force (inertia)

Inertia

Resistance to change in motion (more mass = more inertia)

Balanced forces

Equal forces → no change in motion

Unbalanced forces

Unequal forces → causes acceleration (speed up, slow down, change direction)

Newton’s Second Law

F = ma (greater force = more acceleration, less mass = more acceleration)

Newton’s Third Law

For every action force there is an equal and opposite reaction force (on different objects)

Kinetic energy examples

• motion

• light

• heat

• sound

Potential energy examples

• elastic

• gravitational

• chemical

• static

Law of Conservation of Energy

energy can’t be created or destroyed; only transformed or transferred

Wasted energy

• (mainly) friction

• air resistance

Efficiency formula

efficiency = (useful energy / wasted energy) x 100

Sankey diagram

What is DNA and its two functions?

Deoxyribonucleic acid that:

• carries genetic information for inheritance

• codes for amino acids to produce protein

What are nucleotides, and what three things is it made of?

the basic building blocks of DNA

• deoxyribose sugar

• phosphate

• nitrogenous base

What are the two complementary base pairs?

Adenine (A) + Thymine (T)

Cytosine (C) + Guanine (G)

What is a gene and its function?

a section of DNA that:

• codes for a particular trait

Describe the structure of a chromosome and what it contains.

consists of tightly-coiled DNA (chromatin) that:

• forms a rod-like structure

• contains many genes

What is DNA replication, and when/why does it occur?

the process by which:

• a DNA molecule forms an exact copy of itself (before cell division)

• so cells have identical genetic information

What is a protein, and what does it control?

🧪

an organic compound that is made of amino acids and:

• controls chemical reactions

What is the helicase enzyme responsible for?

enzyme responsible for:

• separating/unzipping the two sides of the DNA molecule

What is the DNA polymerase enzyme responsible for?

enzyme responsible for:

• attaching loose nucleotides to the exposed DNA strand

What is the DNA ligase enzyme responsible for?

enzyme responsible for:

• repairing bonds of nucleotides to form DNA

What is an allele?

• different versions (variations) of the same gene

• inherit one allele from each parent

What is the difference between dominant and recessive alleles?

• dominant alleles → always ignores the recessive allele if at least one is present (uppercase)

• recessive alleles → only expressed if both alleles are recessive (lowercase)

What is the difference between genotypes and phenotypes?

• genotypes → allele combinations for a gene (e.g. RR, Rr, rr)

• phenotypes → an individual’s trait determined by its genotype (e.g. red/white flower)

What is the difference between homozygous and heterozygous?

• homozygous (Ho) → two identical alleles for a given gene

• heterozygous (He) → two different alleles for a given gene

What is the difference between autosomal and sex-linked inheritance?

• autosomal inheritance → genes found on non-sex chromosomes

• genes found on sex chromosomes (usually X chromosome)

What is a sex-linked trait?

a trait controlled by a gene located on a sex chromosome

What is an X chromosome?

• a sex chromosome that carries many genes and traits

• females have XX, males have XY

How to determine if a pedigree is dominant or recessive?

• dominant: trait appears every generation (affected offspring have 1+ affected parents)

• recessive: trait skips a generation (affected offspring dont have affected parents)

How to determine if a pedigree is autosomal or x-linked?

• autosomal: affected males to female ratio is roughly equal

• x-linked: mostly males affected, no father → son inheritance, trait often inherited from mother → son

interphase

 

the stage before mitosis where the cell undergoes:

• growth

• DNA replication

• regular cell functions

cytokinesis

the cell splits into two identical daughter cells

daughter cells

the two new cells formed after mitosis (genetically identical)

sister chromatids

the two identical copies of a chromosome joined in the middle

centromere

the point where sister chromatids are attached

spindle fibres

thin structures that pull chromatids apart during mitosis

mitosis

a type of cell division that:

• produces two identical cells

• keeps the chromosome number the same as the parent cell (2n → 2n)

stages of mitosis (PMAT)

Prophase 

Chromosomes become visible and the nucleus starts to break down. 

Metaphase 

Chromosomes line up in the middle of the cell. 

Anaphase 

Sister chromatids are pulled apart to opposite sides of the cell. 

Telophase 

New nuclei form around each set of chromosomes. 

gametes

sex cells (sperm and egg)

what is different between haploid and diploid?

• haploid (n) → cell with half the number of chromosomes

• diploid (2n) → cell with full set of chromosomes

homologous chromosomes

pairs of chromosomes (one from each parent) that carry the same genes

meiosis

a type of cell division that:

• produces four non-identical gametes

• halves chromosome number (2n → n)

first stage of meiosis ( PMAT[I] )

Meiosis I

Prophase I 

Homologous chromosomes pair up and crossing over occurs. 

Metaphase I 

Chromosome pairs line up in the middle. 

Anaphase I 

Homologous chromosomes are pulled apart. 

Telophase I 

Two cells form, each with half the chromosomes. 

second stage of meiosis ( PMAT[II] )

Meiosis II

Prophase II 

Chromosomes become visible again. 

Metaphase II 

Chromosomes line up in the middle. 

Anaphase II 

Sister chromatids are pulled apart. 

Telophase II 

Four haploid cells are formed. 

evolution

the gradual change in a species’ characteristics over time

natural selection

the process by which a species becomes better adapted to its environment 

variation

the differences that exist between individuals or populations 

selection pressure

the pressure exerted by environmental factors in causing the death of organisms with characteristics not suited to the environment  

favourable trait

traits that are suited to the environment and favour the reproductive success of an individual 

===== in the DNA code leads to ==== in ====

(Theory of Evolution of Natural Selection - 1)

Mutations in the DNA code leads to variation in populations.

(Theory of Evolution of Natural Selection - 1)

more ==== are produced than ==== due to ====

(Theory of Evolution of Natural Selection - 2)

offspring; survive; selection pressures

some ==== are more favourable in ====

(Theory of Evolution of Natural Selection - 3)

variations/traits; their environment

favourable ==== are ==== onto the next ====

(Theory of Evolution of Natural Selection - 4)

traits; passed; generation

Three key steps of speciation

Variation → differences exist within a species

Isolation → groups become separated and cannot breed

Selection → different environments favour different traits over time

allopatric speciation

 Formation of new species due to geographic isolation.

sympatric speciation

Formation of new species within the same location.