Half-Yearly Notes Flashcards

Vocabulary flashcards based on half-yearly notes for exam preparation.

Male reproductive system

The male reproductive system produces, matures and transports sperm for fertilisation. It includes external and internal structures.

Testes

Housed in the scrotum outside the body and produces sperm through spermatogenesis and secretes testosterone.

Testosterone

Male sex hormone produced by Leydig cells in the testes responsible for male secondary sexual characteristics and regulates sperm production and sex drive.

Epididymis

A long, coiled tube behind the testes where sperm mature and are stored, gaining motility and fertilisation ability.

Vas Deferens

A muscular tube that transports mature sperm from the epididymis to the urethra using peristalsis during ejaculation.

Accessory Glands

Glands that add fluids to form semen, which nourishes and protects the sperm.

What do the Seminal Vesicles do

Secretes fructose-rich fluid to provide energy for sperm, contributing around 60% of semen.

What does the Prostate Gland do

Adds alkaline fluid that neutralises vaginal acidity, helping sperm survive.

Bulbourethral (Cowper’s Glands)

Secretes mucus-like fluid to lubricate and cleanse the urethra before ejaculation.

What does the Urethra do

Carries semen through the penis and out of the body.

What is a Penis

Delivers sperm into the female reproductive system during intercourse.

What does the female Reproductive System do

The female reproductive system produces eggs, facilitates fertilisation, and supports the development of a baby during pregnancy.

What are Ovaries

Small almond-shaped organs are on either side of the uterus, release one mature egg (ovum) roughly every 28 days (ovulation), and produce estrogen and progesterone.

What are Fallopian Tubes (Oviducts)

Narrow tubes connecting the ovaries to the uterus, where fertilisation occurs, and lined with cilia to move the egg toward the uterus.

What is the Uterus?

A hollow, muscular organ where the fertilised egg implants and develops.

What does the Endometrium do? (uterine lining)

Thickens to support the embryo and sheds during menstruation if there’s no fertilisation.

What is the Cervix

The lower, narrow part of the uterus produces cervical mucus, opens slightly during ovulation, and dilates during childbirth.

What is the Vagina

Muscular canal that receives the penis during intercourse and acts as the birth canal during delivery.

What is Fertilisation

Occurs in the fallopian tube within 24 hours of ovulation, where one sperm penetrates the outer layer of the egg, and the sperm and egg nuclei fuse, forming a zygote with 46 chromosomes.

What is a Zygote

A single cell formed when the nucleus of the sperm fuses with the nucleus of the egg, containing 23 chromosomes from each parent, and is totipotent, having the potential to form any cell type in the body.

Who was Gregor Mendel?

An Austrian monk and scientist (1822 - 1884) known as the “Father of Genetics” due to his groundbreaking work on inheritance, conducting experiments on pea plants in the mid-1800s.

Controlled Pollination

Crossing plants with different traits by transferring pollen manually.

Monohybrid Crosses (Inheritance of One Trait)

A genetic cross involving one trait with two alleles; offspring (F1 generation) showed only one trait; F2 generation showed a 3:1 ratio.

Dihybrid Crosses (Inheritance of Two Traits)

Studying how two traits were inherited together, showing traits were inherited independently, leading to the law of independent Assortment.

Law of Segregation

Each organism has two copies of a gene (one from each parent); these copies (alleles) separate during gamete (sex cell) formation; offspring inherit one allele from each parent.

Law of Independent Assortment

Different traits are inherited independently of each other (applies only if genes are on different chromosomes or far apart on the same chromosome).

Dominant and Recessive Traits

Some traits (dominant) mask the appearance of others (recessive).

Punnett Square

A diagram used to predict the possible genetic outcomes of a cross between two organisms, showing how alleles are inherited from each parent and illustrating probabilities of inheritance and genetic variation.

Phenotype

The observable physical characteristics of an organism, determined by both the genotype and environmental influences.

Genotype

The term "genotype" refers to the complete genetic makeup of an organism. This includes all the genes and DNA sequences that an individual inherits. The genotype determines the hereditary potential and characteristics of an organism.

Monohybrid Crosses

A genetic cross involving one trait with two alleles.

Dihybrid Crosses

A dihybrid cross involves two different traits inherited independently.

Mitosis

The process that produces two identical daughter cells from a single parent cell, used for growth, repair, and asexual reproduction; daughter cells are diploid (2n).

Meiosis

A special type of cell division that produces gametes (sperm and egg cells), reducing the chromosome number by half, creating four genetically different haploid (n) cells.

Pedigree

A diagram that shows the inheritance of a genetic trait over multiple generations in a family used to track how a trait is passed down.

Autosomal Dominant Inheritance

Affects both males and females equally, does not skip generations, and at least one affected parent must pass on the trait.

Autosomal Recessive Inheritance

Affects both males and females equally, can skip generations, carriers (Aa) do not show symptoms but can pass the gene to offspring; only aa will show the trait.

Sex-Linked Inheritance (X-Linked Recessive)

More males are affected than females and can skip generations, as females can be carriers; males need one affected X chromosome (XaY) to have the trait.

DNA Replication

The process by which a cell makes an exact copy of its DNA, crucial for cell division, ensuring each cell has a complete set of genetic information during the interphase in meiosis and mitosis.

Unwinding the DNA

Unwinds the double-stranded DNA molecule and separates the two strands, creating two single strands.

Base Pairing

Adds new bases (A, T, C, G) to the template strand, where A pairs with T, and C pairs with G, forming two new strands of DNA.

Helicase

The enzyme helicase unwinds the double-stranded DNA molecule by breaking the hydrogen bonds between the complementary base pairs, creating the replication fork.

Mutation

A change in the DNA sequence of an organism, occurring naturally or due to external factors like radiation, chemicals, or viruses during DNA replication or damage.

Gene Mutations

Also called point mutations, they affect a single gene and includes substitutions, insertions, or deletions.

Chromosomal Mutations

Affect whole chromosomes or large sections, including duplication, deletion, inversion, and translocation.

Mutations

Random changes in DNA create new traits.

Spontaneous Mutations

Errors during DNA replication.

Induced Mutations

Caused by mutagens like UV radiation, X-rays, chemicals (tobacco smoke), or viruses.

Neutral Mutations

Term for Mutations that has no impact on the organism.

Beneficial Mutations

Term for Mutations that lead to advantageous traits (e.g., disease resistance).

Harmful Mutations

Term for Mutations tht Cause genetic disorders or diseases (e.g., cancer, cystic fibrosis).

Variation

Changes in traits among individuals in a population, genetic (inherited) or environmentally influenced.

Identical Twins (Monozygotic)

Share 100% of their DNA; differences arise due to the environment.

Fraternal Twins (Dizygotic)

Share only 50% of their DNA; differences result from both genes and the environment.

Recombination (Crossing over in Meiosis)

These exchanges DNA with each other, leading to new gene combinations.

Independent Assortment (Meiosis)

In Metaphase 1, chromosomes line up randomly, ensuring different combinations of parental genes in gametes.

Gene Flow

Migration allows different populations to mix genes, increasing diversity.

GMOs (Genetically Modified Organisms)

Organisms (usually crops or animals) whose DNA has been altered to express desirable traits

Vaccines

Stimulate the immune system to recognise and fight specific diseases.

IVF (In Vitro Fertilisation)

A fertility treatment where an egg is fertilised by sperm outside the body, and then is put back into the uterus.

Key Features of the Watson-Crick Model

Double helix structure, Components of DNA, Base Pairing, Anti-Parallel Strands

DNA (Deoxyribonucleic Acid)

A molecule that carries the genetic instructions for all living things.

James Watson and Francis Crick

Proposed a model explaining the structure of DNA, based on data from scientists like Rosalind Franklin and Maurice Wilkins.

Theory of Natural Selection

Natural selection is where organisms better suited to their environment survive and reproduce, passing on their traits.

Common Ancestry

All species are related through common ancestors.

Gradualism

Evolution happens slowly over a long time.

Speciation

Given enough time, natural selection can create new species.

Disease

A condition that negatively affects how the body functions.

What is an Infectious Disease

Diseases are caused by pathogens (harmful microgranisms) and can spread between individuals.

What Is a Non-Infectious disease

Diseases are not caused by pathogens and cannot be spread between individuals.

What is skin?

Physical barrier.

Mucus and cilia

Trap pathogens in the respiratory system.

Inflammation

Increases blood flow to the infected area to bring more white blood cells.

Fever

Raises body temperature to slow down pathogens.

Phagocytes

Phagocytes are a type of white blood cell that engulf and destroy pathogens.

B cells

Produce antibodies that attach to specific pathogens and neutralise them.

T cells

Destroy infected cells and help B cells.

Memory Cells

after an infection, some B and T cells beocme memory cells for quicker future responses. This… is how immunity develops.

Vaccines

Expose the body to a harmless form of a pathogen to induce immunity without causing disease.

Atom

The smallest unit of matter that retains the properties of an element.

Nucleus

Found at the center of the atom and contains protons and neutrons.

Electron Shells (Energy levels)

Electrons move around the nucelus in specific regions called shells or energy levels.

Atomic Number

Number of protons (also equals number of electrons in a neutral atom).

Mass Number

Number of protons + neutrons.

Who was Johann Dobereiner and what did he do in 1817 regarding element classification?

Johann Dobereiner was a scientist who, in 1817, grouped elements into sets of three, known as triads, based on their similar

Law of Octaves (1864)

Proposed by John Newlands, the Law of Octaves arranged elements by increasing atomic mass, noting that every eighth element shared similar properties, akin to musical octaves. However, this pattern was limited and only applied to elements up to calcium.

Dimitie Mendeleev (1869) - First successful Periodic Table

Organised elements by increasing atomic mass and also grouped them by similar chemical properties and predicted properties of unknown elements.

Who was Henry Moseley and what was the significance of his 1913

In 1913, Henry Moseley discovered that elements should be organized in the periodic table based on their atomic number (number of protons) rather than their atomic mass. This discovery resolved inconsistencies in Mendeleev's table.