Notes, summaries, assignments, exams, and exercises for Biology for Secondary education

Vital Functions of Living Beings

Vital functions refer to the specific actions that support life. There are three main functions:

1. Nutrition: Living beings obtain the matter and energy necessary to sustain life through this function.
2. Interaction: Living beings relate to their surrounding environment through this function.
3. Reproduction: Individual living beings are produced; this ensures the perpetuation of the species.

Biomolecules: The Building Blocks of Life

Biomolecules are the fundamental components of living organisms. They are mainly composed of carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus.

Organic Biomolecules

Organic molecules are exclusive to living beings. There are four main types:

1. Carbohydrates (Saccharides)

   These are the most

Unit 3: Lessons 1

Bioelements

Atoms are linked together to form elements. A chemical element is formed by similar atoms.

Biomolecules

Atoms are linked together to make molecules. There are two types of molecules: inorganic and organic.

Cell

This is the smallest unit of living matter that can exist freely in a medium, as it can carry out all the functions of living beings.

Multicellular Levels

• Tissue: A group of cells similar in structure that work together to perform a specific function.
• Organ: Several tissues grouped together to make a structure with a specific function.
• Organ System: A group of organs with closely related functions.
• Organism: The complete unit of the living being.

Unit 3: Lesson 2

Enzymes

Most chemical reactions in living beings would...

1. Anatomy and Physiology
Anatomy: The study of body structure. It asks: What parts does the body have, and what do they look like?

Physiology: The study of body function. It asks: How do body parts work?

Complementarity: Structure and function are related. The way a body part is built helps it do its job.

Example: Anatomy studies the heart's structure. Physiology studies how the heart pumps blood.

2. Levels of Organization

Memorize the order: subatomic particles > atoms > molecules > macromolecules > organelles > cells > tissues > organs > organ systems > organism

• Subatomic particles: Protons, neutrons, and electrons.
• Atoms: The smallest units of an element.
• Molecules: Two or more atoms joined together.
• Macromolecules: Large

The Excretory System

The excretory system is responsible for eliminating waste substances from the body. The main organs involved are:

• The kidneys: They filter the blood and produce urine.
• The lungs: They eliminate carbon dioxide (CO2).
• The liver: It processes bilirubin (a product of red blood cell breakdown) and excretes it with the feces.
• The sweat glands: They produce sweat to regulate body temperature.

The Urinary System

The urinary system is a key part of the excretory system and is made up of:

• Ureters: Tubes that connect the kidneys to the bladder.
• Urinary bladder: A muscular organ that stores urine.
• Urethra: The tube through which urine leaves the body. In men, the urethra is shared by the urinary and reproductive systems, while in women it is

1. What is the first infective stage of the malarial parasite in man?

Answer: Sporozoite.

2. What is HIV?

Answer: HIV is a virus that causes AIDS by destroying the immune system.

3. Which bacteria causes typhoid?

Answer: Salmonella typhi.

4. What are the different types of barriers in innate immunity?

Answer: Innate immunity includes the following types of barriers:

• Physical barriers: Skin and mucous membranes prevent the entry of pathogens.
• Physiological barriers: Acid in the stomach, tears, and saliva destroy microbes.
• Cellular barriers: Phagocytic cells like neutrophils and macrophages.
• Cytokine barriers: Interferons released by virus-infected cells.

5. What are STDs? Name two examples and preventive measures.

Answer: STDs (Sexually Transmitted Diseases)...

Chemistry Fundamentals and Reactions

Chemical Bonding Types

• Ionic Bonding: Metal + Non-metal → Electrons are transferred.
• Covalent Bonding: Non-metal + Non-metal → Electrons are shared.

Chemical Naming Conventions

• Ionic Naming: Metal + Non-metal (ending in “-ide”). Use Roman numerals for multivalent metals. Includes polyatomic ions.
• Molecular Compounds: Use prefixes (mono-, di-, tri-, etc.).
• Diatomic Elements: H₂, O₂, F₂, Br₂, I₂, N₂, Cl₂.

Properties of Compounds

• Ionic Compounds: Solid state, high melting/boiling points, conducts electricity when dissolved (aqueous).
• Molecular Compounds: Low melting/boiling points, poor electrical conductors.

Balancing Chemical Equations

The process follows the Law of Conservation of Mass:

1. Word Equation
2. Skeleton

Cell Membrane Structure and Function

Question: What is the role of organic molecules in the cell membrane?

Answer: Organic molecules contribute to cell–cell adhesion and protect the cell surface from chemical damage.

How Are Substances Transported Across the Membrane?

There are three main types of membrane transport:

• Passive transport — a type of membrane transport that does not require energy to move substances across cell membranes. Passive transport can use diffusion or osmosis and depends on the concentration gradient.
• Facilitated transport — molecules are transported across the plasma membrane with the help of membrane proteins (examples in common descriptions include oxygen, CO2, and glucose).
• Active transport — uses different protein

Characteristics of Living Things

MRS GREN is an acronym used to remember the seven life processes: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.

• Movement: Observed in living things through actions like jumping or processes like photosynthesis.
• Respiration: A chemical reaction in cells that breaks down nutrient molecules and releases energy for metabolism (e.g., plants release oxygen that is absorbed by other living things).
• Sensitivity: The ability to respond to stimuli, such as touch or light.
• Growth: The process of increasing in size, such as plants getting bigger.
• Reproduction: Male and female members of the same species producing offspring, which can be asexual (e.g., breaking in half) or sexual.
• Excretion:

Types of Mutations

Point Mutations

A change in a single nucleotide.

• Substitution: One nucleotide is incorrectly added in place of the correct complementary nucleotide.
• Insertion: One or more extra nucleotides are added to the growing DNA strand; this can lead to a frameshift.
• Deletion: One or more nucleotides are eliminated from the growing DNA strand; this can lead to a frameshift.

Chromosome Mutations

Changes in the structure or number of chromosomes.

Structural Mutations

These are due to two simultaneous breakages in nuclear chromosomes. This can cause:

• Deletion: The loss of a chromosomal segment.
• Duplication: A region of the chromosome is repeated.
• Inversion: The change in direction of the chromosomal segment.
• Translocation: A segment splits off from

Genetics Terminology

Basic Concepts

• Trait: An inheritable characteristic of an organism.
• Gene: A DNA segment containing information that controls a specific trait.
• Allele: A variant form of a gene, often arising from mutations, contributing to hereditary variations.
• Locus (pl. Loci): The specific location of a gene on a chromosome.

Zygosity

• Homozygous Organism: Possesses identical alleles for a given gene (e.g., AA or aa).
• Heterozygous Organism: Possesses different alleles for a given gene (e.g., Aa).

Allele Interactions

• Dominant Allele: An allele that expresses its phenotype regardless of the paired allele.
• Recessive Allele: An allele that expresses its phenotype only when paired with an identical allele.

Genetic Inheritance Patterns

• Dominance (Dominant