reproduction

Date: The Science Grade 9 Exam is scheduled for Tuesday, June $11$ .
Duration: The exam provides a total length of $2$ hours for completion.
Scope: This is a cumulative exam covering two major units of the curriculum:
- Reproduction
- Atoms and Elements

Asexual Reproduction: Reproduction involving a single parent that produces offspring genetically identical to the parent.
- Types of Organisms: Organisms that reproduce asexually include many bacteria, protists, some plants, and fungi.
- Common Methods: Includes binary fission, budding, fragmentation, and vegetative reproduction.
Sexual Reproduction: Reproduction involving the fusion of two gametes (sperm and egg) from two parents, resulting in genetic variation in the offspring.
Traits and Inheritance: The process by which genetic information is passed from parents to offspring.
Dominant and Recessive Traits:
- Dominant Traits: Traits that are expressed if at least one dominant allele is present (represented by uppercase letters, e.g., $B$ ).
- Recessive Traits: Traits that are only expressed if two recessive alleles are present (represented by lowercase letters, e.g., $b$ ).
Punnett Squares: A tool used to predict the probability of offspring inheriting certain genotypes and phenotypes from a cross between two parents.
Pedigree: A diagram or family tree that represents the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors from one generation to the next.

Mutations: A change in the DNA sequence of an organism.
- Differences between Types of Mutations:
  - Point Mutations: A change in a single nucleotide.
  - Insertions: The addition of one or more nucleotide base pairs into a DNA sequence.
  - Deletions: A mutation in which a part of a chromosome or a sequence of DNA is lost during DNA replication.
Reproductive Success: Specific behaviors and physical traits that organisms develop to ensure they can attract mates and successfully produce offspring.
Biotechnology: The use of living systems and organisms to develop or make products.
- Stem Cell Research: The study of undifferentiated cells that have the potential to develop into many different cell types in the body.
- Cloning: The process of producing genetically identical individuals of an organism either naturally or artificially.
- Genetically Modified Foods (GMOs): Foods derived from organisms whose genetic material has been modified in a way that does not occur naturally by mating and/or natural recombination.

Properties of Matter: Characteristics that can be used to describe or identify matter.
- Physical Properties: Characteristics observed without changing the substance's identity (e.g., color, density, melting point).
- Chemical Properties: Characteristics that describe a substance's ability to undergo specific chemical changes (e.g., flammability, reactivity with acid).
Classification of Matter:
- Pure Substances: Matter that has a uniform and definite composition. This includes:
  - Elements: Substances that cannot be broken down into simpler substances.
  - Compounds: Substances made of two or more elements chemically combined.
- Mixtures: Physical blends of two or more components.
  - Homogeneous Mixtures: Uniform composition (solutions).
  - Heterogeneous Mixtures: Non-uniform composition (mechanical mixtures).
Physical and Chemical Changes:
- Physical Changes: Changes affecting the form of a chemical substance, but not its chemical composition (e.g., boiling, freezing, shredding).
- Chemical Changes: A process where one or more substances are altered into one or more new and different substances (e.g., burning, rusting).

Development of Understanding Elements (Early Chemistry): The historical progression from ancient theories (like the four elements: earth, air, fire, water) to modern atomic theory.
Historical Figures in Atomic Theory:
- John Dalton: Proposed the solid sphere model and atomic theory.
- J.J. Thomson: Discovered the electron using cathode ray tubes and proposed the Plum Pudding model.
- Ernest Rutherford: Discovered the nucleus through the Gold Foil Experiment.
- Niels Bohr: Proposed that electrons move in fixed circular orbits (energy levels) around the nucleus.

Identifying Basic Elements: The ability to identify elements based on their characteristics without the aid of a periodic table.
The First $18$ Elements: Mastery of the elements from Hydrogen ( $H$ ) to Argon ( $Ar$ ) on the periodic table.
Bohr Atomic Model:
- These must be accurate, illustrating the nucleus containing protons and neutrons, with electrons in specific shells.
- Electron Configuration: Maximum of $2$ electrons in the first shell, $8$ in the second, and $8$ in the third for the first $18$ elements.
Atomic Data Points:
- Symbol: The one or two-letter abbreviation (e.g., $He$ for Helium).
- Atomic Number: Represents the number of protons in the nucleus (e.g., Carbon has an atomic number of $6$ ).
- Atomic Mass: The weighted average mass of the atoms in a naturally occurring sample of the element (e.g., Oxygen has a mass of approximately $16.00$ ).
- Element Name: The full name assigned to the chemical symbol.
Chemical Families and Groups: Vertical columns on the periodic table including:
- Noble Gases: Found in Group $18$ , these are chemically inert/unreactive.
- Halogens: Found in Group $17$ , these are highly reactive non-metals.

Chemical Formulas: Symbolic representations of a compound's composition.
- Formulas indicate the elements present and the ratio of atoms (e.g., $H_2O$ for water, $NaCl$ for table salt).
Interpreting Formulas: Calculation of the number of molecules and atoms present in a given chemical expression.
- Subscripts: Indicate the number of atoms of the element immediately preceding the subscript (e.g., in $CO_2$ , there are $2$ Oxygen atoms).
- Coefficients: Numbers placed in front of a formula indicate the number of molecules (e.g., in $2H_2O$ , there are $2$ molecules of water, totaling $4$ Hydrogen atoms and $2$ Oxygen atoms).