Biology Chapter on Organisms and Biotechnology

Introduction

• The book is for Cambridge International Examinations IGCSE Biology (0610)
• It can also be used with the Cambridge 'O' level Biology syllabus (5090)
• The book is divided into Core and Supplement (Supplement marked with 'S' and brown bars)
• Core students do Papers 1, 3 and either 5 or 6. They can get a maximum of a Grade C
• Supplement students do Papers 2, 4 and either 5 or 6. They can get a maximum of a Grade A*
• The CD-ROM has revision checklists and interactive multi-choice questions
• There is a practical Workbook to help develop practical skills
• There are activities to help develop practical skills, marked with a symbol.
• There are 2 practical papers, Paper 5 and Paper 6
• The book has several sets of Questions and longer questions at the end of each chapter to test understanding

Acknowledgements

• The book includes acknowledgments for images, individuals, and organizations.

Contents

• The book has a detailed table of contents listing each chapter and the pages they are on.
• Topics include classification, cells, animal and plant nutrition, transport, pathogens and immunity, respiration, gas exchange and excretion, coordination, reproduction and genetics.
• The book covers the whole syllabus topics in detail
• Each chapter contains summaries for quick review of the main material

Classification

• Living organisms are classified into 7 kingdoms: Animal, Plant, Fungi, Protoctista, Prokaryotes
• Characteristics of living things include growth, movement, sensitivity, excretion, reproduction, nutrition, respiration
• Classification systems use binomial names - genus and species names, both written in italics
• Dichotomous keys help identify organisms by asking questions with only two choices
• The platypus is an example of an animal difficult to classify because it has characteristics of different groups (mammal, bird, fish)
• Modern classification relies heavily on DNA sequences to understand evolutionary relationships

Cells

• Cells are the basic units of life; all organisms are made up of cells
• Different kinds of cells vary in specialized structures
• Microscope types, like light and electron microscopes are essential for studying and observing cell parts
• Cells are made up of various organelles with distinct roles (mitochondria, ribosomes, and nucleus)
• Plant and animal cells have different structures (cell wall, vacuole)
• Cells have membranes that control movement of substances into and out of the cell (diffusion, osmosis, and active transport)
• Organisms are made of an ordered arrangement of cells in tissues, which make up organs and organ systems.

Movement in and out of cells

• Diffusion involves the net movement of molecules or ions from an area of high concentration to one of low concentration.
• Osmosis is the diffusion of water across a partially permeable membrane from an area of high water potential (low solute) to an area of low water potential (high solute)
• Factors like temperature can affect the rate of diffusion (and thus osmosis)
• Active transport moves molecules across membranes against a concentration gradient, with energy input

The chemicals of life

• Living organisms are made from a multitude of different chemicals, including carbohydrates, fats ('lipids'), proteins, and water.
• Water is an essential solvent
• All organisms need carbohydrates, fats and proteins for various functions
• Carbohydrates provide energy
• Fats store large amounts of energy and provide insulation
• Proteins have many roles, including building materials, enzymes, and hormones
• DNA is the genetic material and its structure determines the characteristics of an organism.
• Tests can be used to identify these chemicals in different foods: Benedict's, iodine and biuret tests

Enzymes

• Enzymes are biological catalysts accelerating different chemical reactions in living organisms.
• Enzymes are proteins and are affected by factors as temperature and pH (optimum).
• Enzyme activity can be measured by timing the completion of a particular reaction
• Enzymes, having a specific active site, enable chemical reactions or their breakdown
• Enzyme activity is affected by temperature and pH. High temperatures and extreme pH levels will denature the enzymes
• Enzymes are essential to living organisms

Plant nutrition

• Photosynthesis is the process used by plants to produce glucose.
• Chlorophyll in chloroplasts captures light energy.
• Factors affecting photosynthesis include temperature, light intensity, carbon dioxide concentration, water availability, and nutrient availability
• Plants use carbohydrates produced by photosynthesis for energy, growth, and survival
• Leaves are specialized in absorbing the sunlight for photosynthesis.
• Leaves contain layers or cells like the epidermis that have thin cell walls, stomata and chloroplasts.