Biology_O_Level

Biology O Level Cambridge 2024-2025

Cellular organization: All living organisms are made up of one or more cells, which are the basic units of life.
Metabolism: This encompasses the chemical reactions that occur within organisms to maintain life, including energy production and use.
Homeostasis: Organisms have the ability to maintain stable internal conditions despite changes in their external environment.
Growth and development: Living organisms undergo a series of changes during their life cycle, including growth in size and complexity.
Reproduction: All living organisms have the ability to reproduce, creating offspring and ensuring the continuation of their species.
Response to stimuli: Living organisms can respond to environmental changes, which is essential for survival. Adaptation: Over time, species evolve and adapt to their environments, enhancing their survival and reproductive success.

Types of Cells:

Cell: The basic and smallest unit of life that can replicate independently.
Tissues: Groups of similar cells that work together to perform a specific function.
Organs: Structures composed of different types of tissues that perform specific functions within an organism.
Organ Systems: Complex structures formed by multiple organs that work together to carry out a particular function in the body.

Comparison of Animal & Plant Cells, detailing structural components and their functions, notably cell walls (in plants) and chloroplasts (in plants).

Cell Type

Animal Cells

Plant Cells

Cell Wall

Yes (Cellulose)

Chloroplasts

Yes (Photosynthesis)

Cell Membrane: Semi-permeable barrier that regulates entry and exit of substances.
Nucleus: Contains genetic material (DNA) and controls cellular activities through gene expression.
Cytoplasm: Site for metabolic activity, hosting organelles and cellular components.
Mitochondria: Powerhouse of the cell, where aerobic respiration occurs, producing ATP.
Ribosomes: Sites of protein synthesis, translating mRNA into polypeptides.

Cell Wall: Provides structural support, protection, and shape to the plant cell.
Chloroplasts: Organelles where photosynthesis occurs, converting sunlight into chemical energy (glucose) using CO2 and H2O.
Vacuoles: Large organelles in plant cells for storage of substances (such as water, nutrients), maintaining turgor pressure and cell structure.

Unicellular organisms without a nucleus and possessing unique genetic organization, such as circular DNA and plasmids that can confer advantageous traits (e.g., antibiotic resistance).

Ciliated Cells: Facilitate movement of mucus in the respiratory tract, helping to trap and expel pathogens.
Neurons: Specialized for transmitting signals throughout the body, functioning in communication between body parts.
Red Blood Cells: Specialized cells mainly responsible for oxygen transport via hemoglobin.
Gametes (Sperm and Egg Cells): Specialized cells involved in sexual reproduction, contributing genetic material to offspring.

Root Hair Cells: Adapted for maximum absorption of water and minerals from the soil through increased surface area.
Palisade Mesophyll Cells: Located just beneath the leaf surface, packed with chloroplasts for efficient photosynthesis.

Overview of magnification concepts, including the use of microscopes to view cellular structures.

Diffusion: The passive movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached.
Osmosis: A specific type of diffusion involving the movement of water molecules across a semi-permeable membrane.
Active Transport: The process of moving molecules against their concentration gradient, requiring energy (ATP).

Example: The process by which root hair cells absorb essential mineral nitrates from the soil against their concentration gradient, critical for plant growth and development.

Comparisons of diffusion and active transport characteristics, highlighting their significance in maintaining cellular homeostasis.

In-depth exploration of the composition, structure, and roles of carbohydrates, proteins, lipids, and nucleic acids in biological systems and processes.

Examining the structure and function of enzymes, their role in catalyzing biochemical reactions, and their importance in processes such as digestion and biotechnology.

Detailed discussions on genetics, variation, biotechnology applications, ecosystem dynamics, population studies, environmental impacts, conservation methods, and human health & disease management, embracing the complexity and interrelatedness of biological phenomena.