y10 science sem 1

What is genetics?

The study of heredity and inherited characteristics.

Who is considered the father of genetics?

Gregor Mendel

What are chromosomes?

Structures of tightly-wound DNA found in the nucleus of living cells.

What are genes?

Basic units of heredity contained within chromosomes.

What molecule contains genetic information?

DNA (Deoxyribonucleic Acid)

What is a nucleotide?

A subunit of DNA consisting of phosphate, deoxyribose sugar, and a base.

Describe the structure of DNA.

A double helix consisting of two chains that twist around each other, resembling a ladder with 'rungs' made of base pairs.

What are the four bases in DNA?

Adenine, Thymine, Guanine, and Cytosine

Which bases pair together in DNA?

Adenine with Thymine, and Guanine with Cytosine

Define a gene.

A section of a DNA molecule that provides instructions for building a specific protein.

What is inheritance?

The passing down of traits via genes from one generation to the next.

What is the role of RNA?

A molecule that converts information stored in DNA into proteins.

What bases are found in RNA?

Adenine, Uracil, Cytosine, and Guanine

What are the three main types of RNA?

Messenger RNA (mRNA), Ribosomal RNA (rRNA), and Transfer RNA (tRNA)

What is translation?

The process where a cell builds protein using mRNA.

What is transcription?

The process where a section of DNA (gene) is changed into RNA (mRNA).

What is the genetic code?

The set of rules used by a cell to convert genetic information into proteins.

What are the two main functions of chromosomes in cells?

Maintaining normal function of cells (growth and repair = Mitosis) and passing on genetic information to offspring (Meiosis).

What is the diploid number in human somatic cells?

46 chromosomes

What is the haploid number in human sex cells (gametes)?

23 chromosomes

What is a chromatid?

Each strand of a duplicated chromosome.

What is a centromere?

The area where each pair of chromatids is joined.

What are the phases of mitosis?

Prophase, Metaphase, Anaphase, Telophase (PMAT)

What happens during interphase?

Cell growth and development, DNA replication.

What is cytokinesis?

The division of the cytoplasm and organelles after the nucleus divides.

What is meiosis?

A type of cell division that produces sex cells (gametes) for reproduction, resulting in 4 genetically different daughter cells.

What are gametes?

Special sex cells (Eggs and Sperm).

What is fertilization?

When an egg cell and a sperm cell fuses together.

What is a homologous pair?

Two chromosomes that contain versions of the same genes

What is a pedigree?

Family trees that show how a trait is passed down from one generation to the next.

What are sex chromosomes?

Chromosomes that determine a person's sex (XX for females, XY for males).

What is autosomal inheritance?

Inherited traits that are not sex-specific.

What are alleles?

Different versions of a gene.

What is a dominant trait?

A feature that appears when at least one allele is present.

What is a recessive trait?

A feature that appears only when both alleles are present.

What is a genotype?

The written representation we give for a phenotype.

What is a Punnett Square used for?

To determine the genotype and phenotype and the possibility of each.

variations

Differences in traits between individuals of the same species

traits

any feature of an organism

acquired traits

a feature gained during an individual's lifetime

genetic traits

features passed down by genes to the next generation

mutations

small, random changes in DNA

evolution

The change in genetic traits in a population over many generations

population

a group of organisms of the same species living in the same place

genetic variation

differences in features or DNA between individuals of the same species

genetic diversity

the amount of genetic variation

natural selection

the survival of organisms that are better adapted to their environment

selective agents

The environmental factor that acts on a population

selective pressure

a challenge that affects an organism's ability to survive and reproduce

artificial selection

The process by which we choose to breed particular organisms with desirable features

adaptations

A genetic trait that helps an organism survive in its environment

structural adaptations

A physical feature of the body

behavioural adaptations

A behaviour or action

physiological adaptations

An internal body process

speciation

the process by which one species splits into two or more new species

species

A group of organisms that can breed to produce fertile offspring

5 steps to speciation (VISIT)

variation, isolation, selection, inheritance, time

variation in speciation

must exist in the species (caused by mutation)

isolation in speciation

stops gene exchange (interbreeding)

selection in speciation

survival of the fittest e.g. competition

inheritance in speciation

favourable characteristics are passed onto the next generation via genes

time in speciation

over many generations

the fossil record

the history of life on earth told through fossils

comparative anatomy

the study of comparing anatomical structures of species with other species and their evolutionary relationships

comparing dna

organisms with similar anatomy have more genes in common as we would expect they share a common ancestry

biodiversity

the variety of life

common ancestor

a species that two or more other species have evolved from

universe

all of space and time and the matter and energy they contain

astronomy

the study of the universe

galaxies

clusters of billions of stars held together by gravity

star

a hot, bright ball of gas held together by gravity

planet

a natural satellite that orbits a star

moon

a natural satellite that orbits a planet

asteroids

irregular, rocky objects that orbit a star, often in large belts

comets

masses of ice and dust that orbit a star along very oval paths

light-year

the distance light travels in one year

what is the distance of a light year?

9.5 × 10^12km (9.5 trillion)

magnitude

how astronomers measure the brightness of a star

apparent magnitude

the brightness of an object as it appears in the in the night sky

absolute magnitude

measures the brightness of a celestial object if it was placed at a certain distance from Earht

what is the standard distance from Earth that absolute magnitude is measured at?

10 parsecs or 32.6 light years

nuclear fusion

a nuclear reaction in which two atomic nuclei join together

at what temperature does nuclear fusion occur?

13 million degrees

what happens as a result of nuclear fusion?

hydrogen is converted into helium

massive amounts of heat and light are released

main sequence stars

a star that is fusing hydrogen and in a stable state

how are stars formed?

they begin as vast clouds of dust and gas called nebulas

gravity pulls the gas into a dense ball called protostars

as the gas condenses, the temperature begins to increase

a star is formed once hydrogen fuses into helium and nuclear fusion begins

nebulas

vast clouds of dust and gas

protostars

dense balls of gas that haven’t yet developed into a star

small star

a star with less than 8 times the mass of the sun

what is the life cycle of a small star?

once hydrogen begins to run out, it begins to fuse helium, causing the outer layers to expand into a red giant

it further expands into a planetary nebula as the outer layers escape the core’s gravity

once the outer layers have drifted away, what is left is the hot, dense core known as a white dwarf

the core eventually cools off into a black dwarf

red giant

a small star that fuses helium, causing its outer layers to expand

planetary nebula

a nebula formed from a red giant

white dwarf

the remains of the core of a small star

large star

a star at least 8 times the mass of the sun

what is the life cycle of a large star?

the large mass allows the star to keep fusing past carbon and oxygen, forming red supergiants

it ejects most of their mass in catastrophic explosions known as supernovas

after a supernova explosion, a star leaves behind either a neutron star or a black hole

red supergiant

a large star that fuses helium, causing its outer layers to expand

supernova

an explosion of a red supergiant

neutron star

the tiny remains of the core of a large star made up of densely packed neutrons

black hole

an object that has gravity so strong that not even light can escape it

the big bang theory

the universe was created when a tiny, super-dense, super-hot mass exploded and began expanding very rapidly, eventually cooling and forming into the stars and galaxies we observe today.