Complete Biology for Cambridge IGCSE - Third Edition - Notes
Complete Biology for Cambridge IGCSE Third Edition - Notes
Front Pages
The book is for the updated syllabus.
It is an Oxford University Press publication.
The author is Ron Pickering.
IGCSE is a registered trademark of Cambridge International Examinations.
The publisher thanks Cambridge International Examinations for permission to reproduce past paper questions.
Exam-style questions and sample answers were written by the author unless otherwise indicated.
Introduction
Biology is the study of life and living organisms.
Biology has evolved from studying the structure of dead organisms to studying their function.
Advances in biological knowledge raise ethical issues concerning the environment, health, and genetic information.
The book is organized into two-page units called "spreads," grouped into five sections, with a fifth section for practical assessment preparation.
Tips for Using the Book:
Use the contents page for large topics.
Use the index for specific words.
Use the questions to check learning.
Harder questions are marked with a specific icon (icon not provided).
The IGCSE Biology Revision Guide contains more questions and revision tips.
Marks to Look Out For:
A line down the text indicates material for Extended Level only.
An asterisk indicates extension material not normally tested in the IGCSE examination.
Contents - Chapter Summary
1 Characteristics and Classification of Living Organisms
1.1 Biology is the Study of Life and Living Organisms
1.2 The Variety of Life: Classification using morphology, anatomy, protein structure, chromosome number or gene sequence
1.3 Plants
1.4 Invertebrate Animals
1.5 Vertebrate Animals: Five Classes
1.6 Organisms are Made Up of Cells
1.7 The Organisation of Living Organisms
2 Organisation and Maintenance of Organisms
2.1 Movement In and Out of Cells: Diffusion
2.2 Movement In and Out of Cells: Osmosis
2.3 All Living Things Are Made Up of Organic Molecules: Carbohydrates, Lipids, Proteins, Nucleic Acids
2.4 Testing for Biochemicals
2.5 Enzymes Control Biochemical Reactions in Living Organisms
2.6 Enzyme Experiments and the Scientific Method
2.7 Photosynthesis and Plant Nutrition
2.8 The Rate of Photosynthesis
2.9 Leaf Structure and Photosynthesis
2.10 The Control of Photosynthesis
2.11 Photosynthesis and the Environment
2.12 Plants and Minerals
2.13 Food and the Ideal Diet: Carbohydrates, Lipids, and Proteins
2.14 Food and the Ideal Diet: Vitamins, Minerals, Water, and Fiber
2.15 Food Is the Fuel That Drives the Processes of Life.
2.16 Balancing Energy Intake and Energy Demand: Problems Causing Malnutrition
2.17 Animal Nutrition Converts Food Molecules to a Usable Form
2.18 Ingestion Provides Food for the Gut to Work On
2.19 Digestion Prepares Useful Food Molecules for Absorption
2.20 Absorption and Assimilation Make Food Available
2.21 Uptake of Water and Minerals by Roots
2.22 Transport Systems in Plants
2.23 Transpiration: Water Movement Through the Plant
2.24 The Leaf and Water Loss
2.25 Transport Systems in Animals Use Blood as the Transport Medium
2.26 The Circulatory System
2.27 Capillaries: Materials Are Exchanged Between Blood and Tissues, and Tissue Fluid is Formed
2.28 The Heart Is the Pump for the Circulatory System
2.29 Coronary Heart Disease
2.30 Health and Disease
2.31 Pathogens Are Organisms That Cause Disease
2.32 Preventing Disease: Safe Food
2.33 Individuals and the Community Can Fight Disease Together
2.34 Combating Infection: Blood and Defense Against Disease
2.35 Antibodies and the Immune Response
2.36 Respiration Provides the Energy for Life
2.37 Contraction of Muscles Requires Energy Supplied by Respiration
2.38 The Measurement of Respiration
2.39 Gas Exchange Supplies Oxygen for Respiration
2.40 Breathing Ventilates the Lungs
2.41 Smoking and Disease
2.42 How Do We Know That Smoking Causes Disease?
2.43 Excretion: Removal of the Waste Products of Metabolism
2.44 Dialysis and the Treatment of Kidney Failure
2.45 Homeostasis: Maintaining a Steady State
2.46 Control of Body Temperature
2.47 Coordination: The Nervous System
2.48 Neurons Can Work Together in Reflex Arcs
2.49 Integration by the Central Nervous System
2.50 Receptors and Senses: The Eye as a Sense Organ
2.51 The Endocrine System
2.52 Drugs and Disorders of the Nervous System
2.53 Sensitivity and Movement in Plants: Tropisms
3 Development of Organisms and the Continuity of Life
3.1 Reproduction Is an Important Characteristic of Living Organisms
3.2 Reproduction in Flowering Plants: Flowers
3.3 Pollination: The Transfer of Male Sex Cells to Female Flower Parts
3.4 Fertilisation and the Formation of Seed and Fruit
3.5 Germination of Seeds
3.6 Reproduction in Humans
3.7 The Menstrual Cycle
3.8 Copulation and Conception
3.9 Contraception
3.10 Pregnancy: The Role of the Placenta
3.11 Pregnancy: Development and Antenatal Care
3.12 Birth and the Newborn Baby
3.13 Sexually Transmitted Infections
3.14 Variation and Inheritance
3.15 DNA, Proteins and the Characteristics of Organisms
3.16 How the Code Is Carried
3.17 Cell Division
3.18 Inheritance
3.19 Studying Patterns of Inheritance
3.20 Inherited Medical Conditions and Codominance
3.21 Sex Is Determined by X and Y Chromosomes
3.22 Variation
3.23 Causes of Variation
3.24 Variation and Natural Selection: The Evolution of Species
3.25 Natural Selection
3.26 Artificial Selection
4 Organisms and Their Environment
4.1 Ecology and Ecosystems
4.2 Flow of Energy: Food Chains and Food Webs
4.3 Feeding Relationships: Pyramids of Numbers, Biomass and Energy
4.4 Decay Is a Natural Process
4.5 The Carbon Cycle
4.6 The Nitrogen Cycle
4.7 Water Is Recycled Too!
4.8 Factors Affecting Population Size
4.9 Human Population Growth
4.10 Bacteria Are Useful in Biotechnology and Genetic Engineering
4.11 Humans Use Enzymes from Bacteria
4.12 Using Fungi to Produce Antibiotics: Drugs to Control Bacterial Disease
4.13 Baking and Brewing: The Economic Importance of Yeast
4.14 Genetic Engineering
4.15 Food Supply: Humans and Agriculture
4.16 Land Use for Agriculture
4.17 Damage to Ecosystems: Malnutrition and Famine
4.18 Human Impacts on the Environment: Pollution
4.19 Pollution of Water: Eutrophication
4.20 Humans May Have a Positive Effect on the Environment: Conservation of Species
4.21 Managing Fish Stocks: Science and the Fishing Industry
4.22 Conservation Efforts Worldwide
4.23 Conservation of Resources: Recycling Water by the Treatment of Sewage
4.24 Saving Fossil Fuels: Fuel from Fermentation
4.25 Recycling: Management of Solid Waste
5 Practical Biology
5.1 Practical Assessment
5.2 Laboratory Equipment
1.1 Biology is the study of life and living organisms
Scientists believe that Earth was formed from gases about 5 billion years ago and the first living organisms appeared roughly 2.8 billion years ago.
Biologists use a common list of characteristics to classify something as a living thing:
Respire.
Show irritability (sensitivity to environment) and movement.
Nourish themselves.
Grow and develop.
Excrete.
Reproduce.
The acronym RINGER can be used to remember the list.
Living things have a complex organization, variation, and dependence on energy.
Life is defined as a set of processes resulting from matter organization that depends on energy expenditure.
1.2 The variety of life
Classification: The science of placing organisms into categories based on their observable characteristics.
Scientists use it in conservation, understanding evolutionary relationships.
A series of questions used to classify organisms is called a classification key.
Based on their observable characteristics, organisms are distributed into the five kingdoms: prokaryotes, protoctistans, plants, fungi, and animals.
Hierarchy of Classification: Kingdom, Phylum, Class, Order, Family, Genus, Species.
A binomial system of nomenclature organisms a two-part name made up of their genus and species (e.g., Panthera leo for the lion).
New species today may be classified based on characteristics such as protein structure, chromosome number, or gene (DNA or RNA) sequence.
Closely-related organisms have very similar amino acid sequences in proteins such as hemoglobin.
Also, they have very similar base sequences in DNA.
Viruses are not included in the five-kingdom system because they don't respire, nourish or reproduce unless inside a host cell.
A typical virus consists of genetic material (DNA or RNA) protected by a protein coat.
1.3 Plants
Plants are autotrophs, manufacturing food by photosynthesis, and have chlorophyll, definite cellulose cell walls.
Groups include algae, mosses, ferns, and seed plants.
Ferns have roots, stems, complex leaves, and vascular tissues, and reproduce by producing spores.
Angiosperms (flowering plants) are the most successful plants. They are adapted to dry land with flowers, fruits, stomata, vascular systems, and extensive root systems.
Angiosperms consist of monocotyledons and dicotyledons (eudicotyledons).
1.4 Invertebrate animals
Animals are divided into vertebrates and invertebrates, based on the presence of a backbone.
Annelids have long, segmented bodies, and chaetae (bristles).
Nematodes are often parasites inside the gut of another animal and have long, cylindrical body.
Molluscs are protected by a hard shell.
Arthropods, the most numerous animals, includes four classes:
Crustaceans (e.g. Crabs)
Insects (e.g. housefly, mosquito)
Metamorphosis allows them to use the resources of their habitat to the maximum and they are highly adapted for locomotion and reproduction.
Myriapods(e.g. Millipedes)
Arachnids (e.g. Spiders)
1.5 Vertebrate animals: five classes
Vertebrates have a bony internal skeleton with a backbone.
The five classes of vertebrates are:
Fish contain scales and fins, adapted for aquatic life
Amphibians often have moist skin and four limbs, adapted for both water and land.
Reptiles and possess dry, scaly skin with limbs for crawling and climbing
Birds have feathers, wings, and beaks, adapted for flight and endothermy
Mammals possess fur, mammary glands, and a diaphragm, also endothermic and colonize the largest range of habitats in the vertebrate animals.
Humans adapt their environment to suit their own lifestyle and have advanced brain development, upright posture, and hands to use tools.
1.6 Organisms are made up of cells
All living organisms are made up of cells that have three common features: a cell surface membrane, cytoplasm and a nucleus.
Plant cells are made of a cellulose cell wall, a vacuole and possibly chloroplasts.
Cells are too small to bee seen with the naked eye, so a microscope is used to study them.
A light microscope can magnify about 400 times.
The correct (or true) size of an organism can be calculated using a combination of actual measurement and a known magnification.
Using \$Magnification = \frac{Measured}{Actual}\$
1.7 The organisation of living organisms
Different types of cell have particular structures designed to help them carry out different tasks and functions - they have become specialised.
Cells with similar structures and functions are massed together in tissues.
Several tissues may be combined to form an organ, a complex structure with a particular function.
In complex organisms, several organs work together to perform a particular task. These organs form an organ system.
2.1 Movement in and out of cells: diffusion
Cytoplasm is surrounded by a cell surface membrane, it acts as a boundary between the cell contents and its surroundings.
Materials may pass in and out of cells by diffusion, osmosis, active transport.
Diffusion is defined as:
the net movement of molecules within a gas or liquid
from a region of high concentration to a region of lower concentration (down a concentration gradient)
as a result of their random movement
until an equilibrium is reached.
Partially permeable membranes does not allow all particles to pass through.
Diffusion is the main process by which substances move over short distances in living organisms.
To speed up diffusion, organisms adapt by:
having short diffusion distances
maintaining concentration gradients
having large diffusion surfaces
2.2 Movement in and out of cells: osmosis
In living organisms, the solvent is water and the solution is called an aqueous solution.
Osmosis can be defined as:
the diffusion of water molecules
from a region of higher concentration of water molecules to a region of lower concentration of water molecules
down a water potential gradient
through a partially permeable membrane.
Plant and animal cells must maintain osmoregulation.
2.3 All living things are made up of organic molecules
Organic molecules contain carbon and hydrogen atoms, and organisms need them for energy and tissue repair.
The main organic chemical categories in living thing are carbohydrates, lipids, proteins, and nucleic acids.
The study of the organic and inorganic molecules that make up living organisms is called biochemistry. The sum all of the chemical reactions in living organisms is sometimes called metabolism.
Large organic molecules are usually made up of subunits. The subunits can be split apart by a reaction called hydrolysis, which uses water and can be joined together again by condensation.
Carbohydrates: simplest are monosaccharides, which are sources of energy. Polysaccharides are insoluble, so they are good stores of energy and can form important structures such as cellulose cell walls.
Lipids: insoluble in water, are excellent stores of energy, and form barriers between watery environments.
Proteins: made up of amino acids (soluble) coded for by genes. The function of proteins depends on this shape (e.g., the active site of enzymes, and the binding site of antibodies)
**Nucleic acids: **In DNA chains twisted around one another to form a double helix carrying the genetic information.
2.4 Testing for biochemicals
Scientists often need to know whether or not a particular type of molecule is present in a solution.
To test for starch add iodine.
To test for protein add biuret reagent.
To test for glucose (a reducing sugar), add Benedict's reagent.
To test for Vitamin C, the number of drops of solution required to remove the colour of DCPIP determined. Few drops means high concentration of Vitamin C.
The emulsion test indicates the presence of lipids.
A control is needed to make sure that results are valid: known solutions containing the substance should give a positive result, while water should give a negative result.
2.5 Enzymes control biochemical reactions in living organisms
Anabolic reactions build up large molecules from smaller ones, and usually require an input of energy. Catabolic reactions break down large molecules into smaller ones, and often release energy.
Enzymes are proteins that function as biological catalysts. Different enzymes involved in anabolic and catabolic reactions.
Intracellular enzymes work inside of the cells. Extracellular enzymes are released from cells to perform their function.
Enzymes are specific and increase reaction rate by lowering the energy needed for the reaction.
2.6 Enzyme experiments and the scientific method
The scientific method starts with an observation, then a hypothesis, predictions, and experiments, and ends with data analysis and conclusions.
Experiments measure the effect of changing one factor (variable) on the value of a second factor (variable).
A control experiment is also set up, in which the input variable (the temperature) is not changed to make sure the input variable is causing the changes.
Raw data is gathered in a table and may be manipulated or displayed as a graph.
Experiments include evaluation of techniques and apparatus to ensure reliable results.
2.7 Photosynthesis and plant nutrition
Plants, like animals, require raw materials for building tissues and as a source of energy.
Photosynthesis is the basic process by which plants manufacture carbohydrates from raw materials using energy from light.
Chlorophyll allows the energy in sunlight to drive chemical reactions. Chloroplasts act as energy transducers, converting light energy into chemical energy.
Photosynthesis is the process in which light energy, trapped by chlorophyll, is used to convert carbon dioxide and water into glucose and oxygen.
Plants are autotrophic and are essential for heterotrophic organisms since they provide complex food compounds and supply of oxygen.
\$6CO2 + 6H2O^{light\ energy,\ chlorophyll} C6H{12}O6+6O2\$
2.8 The rate of photosynthesis
The rate of photosynthesis can be measured by the rate of oxygen production or absorption 14CO2.
Qualitative and quantitative tests can be used to measure photosynthesis.
The simplest apparatus for measuring oxygen release depends on counting the number of oxygen bubbles given off in a fixed length of time.
2.9 Leaf structure and photosynthesis
The leaf is well adapted to photosynthesis through:
a method for exchange of gases between the leaf and its surroundings
delivering of water to the leaf
removal of glucose
absorption of light energy.
Key features of leaf include the waxy cuticle, upper and lower epidermis, palisade and spongy mesophyll, stomata, and a vein (xylem and pholem).
Photosynthesis and stomata function are related in the fact that the plant needs the carbon dioxide for photosynthesis yet the stomata on their operation, also release water, something that the plants have to counter by using leaves, chlorophyll, etc that are better for their environment.
2.10 The control of photosynthesis
The process of photosynthesis depends upon light availability, pigment for absorption, a supply of carbon dioxide and water, and a suitable temperature.
Limiting factor: varies at different times and under different conditions.
The three most important factors that control the rate of photosynthesis are carbon dioxid \$ CO_ \$), light intensity, and temperature.
2.11 Photosynthesis and the environment
Photosynthesis removes carbon dioxide from the atmosphere, releasing oxygen. This is the opposite of respiration.
Green plants both photosynthesize and respires:
If photosynthesis exceeds respiration plants take in carbon dioxide and add oxygen,If Photosynthesis is less than Respiration plans Remove oxygen and add carbon dioxide.
The balance can be demonstrated by measuring carbon dioxide with hydrogencarbonate indicator in the air.
The compensation point is when the rates of respiration and photosynthesis exactly balance one another and there is no net uptake or loss of carbon dioxide or oxygen.
Plants also produced sucrose, starch, lipids, amino acids and nucleic acids.
Carbon is recycles between simple inorganic and complex organic compounds, connecting plants, animals and other organisms.
2.12 Plants and minerals
Plants require minerals (ions) to build food molecules such as amino acids, proteins, and nucleic acids out of the carbohydrates made by photosynthesis.
2.13 Food and the Ideal Diet: Carbohydrates, Lipids, and Proteins
A healthy, balanced diet is essential for good health.
Energy is measured in joules (J) or kilojoules (kJ). Fat has the highest energy content providing 39kJ per gram. Carbohydrate and lipid intake should be controlled to avoid obesity.
The main groups of food are carbohydrates, lipids, proteins, vitamins, minerals, water, and fiber (or roughage).
Nutrition labels on food packaging include details on energy content, protein, carbohydrate, fat, fiber, and salt.
2.14 Food and the Ideal Diet: Vitamins, Minerals, Water, and Fiber
Vitamins and minerals are needed in small amounts and are essential for good health.
Vitamin C: Important for the immune system and iron absorption; deficiency leads to scurvy.
Vitamin D: Needed for calcium absorption and strong bones and teeth; deficiency leads to rickets.
Iron: Needed for making hemoglobin in red blood cells; deficiency leads to anemia.
Calcium: Important for strong bones and teeth; deficiency can lead to osteoporosis.
Water: Transports substances in the blood, helps in temperature regulation, and is a solvent for chemical reactions.
Fiber: important in providing bulk for the intestine to work on.
2.15 Food Is the Fuel That Drives the Processes of Life.
Food provides energy for all life processes.
Energy is released during respiration which can be used for muscle contraction, protein synthesis, cell division, active transport, and the maintenance of body temperature.
2.16 Balancing Energy Intake and Energy Demand: Problems Causing Malnutrition
A balanced diet involves matching energy input with energy demand.
Imbalances can lead to malnutrition, which includes both undernutrition and overnutrition.
Undernutrition can lead to deficiencies and wasting.
Overnutrition can lead to obesity, increasing the risk of heart disease, diabetes, and some cancers.
2.17 Animal Nutrition Converts Food Molecules to a Usable Form
Animals are heterotrophic, depending on complex organic food.
Digestion breaks down large, insoluble molecules into smaller, soluble ones that can be absorbed into the bloodstream.
The human digestive system consists of the alimentary canal and associated glands.
2.18 Ingestion Provides Food for the Gut to Work On
Ingestion is the taking of substances (e.g., food and drink) into the body through the mouth.
Mechanical digestion increases the surface area of food for enzyme action.
Saliva contains amylase, which starts the digestion of starch into maltose.
2.19 Digestion Prepares Useful Food Molecules for Absorption
Digestion involves both mechanical and chemical processes.
The stomach mixes food with gastric juices containing hydrochloric acid and pepsin.
Hydrochloric acid kills bacteria and provides an acidic pH for pepsin to work that hydrolyzes proteins.
Protease (such as trypsin and pepsin) digests proteins into amino acids.
Lipase digests lipids into fatty acids and glycerol.
Amylase digests starch into glucose.
Bile emulsifies fats, increasing the surface area for lipase action released by the liver and stored in the gall bladder.
2.20 Absorption and Assimilation Make Food Available
Absorption is the movement of digested food molecules through the wall of the intestine into the blood or lymph.
The small intestine is adapted for absorption with villi that increase the surface area.
Villi contain a network of capillaries and a lacteal for the absorption of digested food.
Assimilation is the movement of digested food molecules into body cells where they are used, becoming part of the cells.
2.21 Uptake of Water and Minerals by Roots
Plants take up water and mineral ions from the soil through their roots.
Root hair cells increase the surface area for absorption.
Water moves into root hair cells by osmosis.
Mineral ions are absorbed by active transport.
2.22 Transport Systems in Plants
Plants have vascular tissues (xylem and phloem) for transport.
Xylem transports water and mineral ions from the roots to the leaves.
Phloem transports sugars (sucrose) and amino acids from the leaves to other parts of the plant.
2.23 Transpiration: Water Movement Through the Plant
Transpiration is the loss of water vapor from the leaves of plants through the stomata.
The transpiration stream is the movement of water from the roots, through the xylem, and out of the leaves.
It helps to cool the plant, transport mineral ions, and provide water for photosynthesis.
2.24 The Leaf and Water Loss
The rate of transpiration is affected by environmental factors such as temperature, humidity, wind speed, and light intensity.
Plants have adaptations to reduce water loss, such as a thick waxy cuticle, sunken stomata, and reduced leaf surface area.
2.25 Transport Systems in Animals Use Blood as the Transport Medium
Animals have transport systems to carry substances around the body.
Blood is the transport medium in many animals.
Blood consists of plasma, red blood cells, white blood cells, and platelets.
Red blood cells contain hemoglobin, which transports oxygen.
White blood cells defend the body against infection.
Platelets help in blood clotting.
Plasma transports carbon dioxide, digested food, urea, hormones, and heat.
2.26 The Circulatory System
The circulatory system transports blood around the body.
It consists of the heart, blood vessels (arteries, veins, and capillaries), and blood.
Arteries carry blood away from the heart and have thick, elastic walls.
Veins carry blood towards the heart and have thinner walls and valves to prevent backflow.
Capillaries are tiny vessels with thin walls that allow exchange of substances between the blood and body cells.
2.27 Capillaries: Materials Are Exchanged Between Blood and Tissues, and Tissue Fluid is Formed
Tissue fluid is formed when plasma is forced out of the capillaries.
It surrounds the body cells, allowing exchange of oxygen, nutrients, and waste products.
Most of the tissue fluid returns to the capillaries, while the rest enters the lymphatic system.
2.28 The Heart Is the Pump for the Circulatory System
The heart is a muscular organ that pumps blood around the body.
It has four chambers: two atria and two ventricles.
Valves prevent backflow of blood.
The heart pumps blood in two circuits: pulmonary (to the lungs) and systemic (to the rest of the body).
2.29 Coronary Heart Disease
Coronary heart disease (CHD) is caused by the build-up of fatty deposits in the coronary arteries.
This reduces blood flow to the heart muscle, leading to angina or heart attack.
Risk factors for CHD include smoking, high blood pressure, high cholesterol, obesity, lack of exercise, and
Coronary heart disease (CHD) is caused by the build-up of fatty deposits in the coronary arteries.
This reduces blood flow to the heart muscle, leading to angina or heart attack.
Risk factors for CHD include smoking, high blood pressure, high cholesterol, obesity, lack of exercise, and genetic factors.
2.30 Health and Disease
Health is a state of physical, mental, and social well-being, not merely the absence of disease or infirmity.
Disease is a condition that impairs the normal functioning of the body.
Diseases can be caused by pathogens, genetic factors, environmental factors, or lifestyle choices.
2.31 Pathogens Are Organisms That Cause Disease
Pathogens are microorganisms that cause infectious diseases.
Types of pathogens include bacteria, viruses, fungi, and parasites.
Pathogens can spread through direct contact, air, water, food, or vectors (e.g., mosquitoes).
2.32 Preventing Disease: Safe Food
Safe food handling and preparation are essential for preventing foodborne diseases.
Key practices include washing hands, cooking food thoroughly, preventing cross-contamination, and storing food properly.
2.33 Individuals and the Community Can Fight Disease Together
Individuals can protect themselves and others by practicing good hygiene, getting vaccinated, and avoiding risky behaviors.
Communities can promote health through public health programs, sanitation, and access to healthcare.
2.34 Combating Infection: Blood and Defense Against Disease
The blood plays a crucial role in defending the body against infection.
White blood cells (leukocytes) are involved in the immune response.
There are different types of white blood cells, including phagocytes and lymphocytes.
2.35 Antibodies and the Immune Response
Antibodies are proteins produced by lymphocytes that recognize and bind to specific antigens (foreign substances).
The immune response involves the production of antibodies and the activation of other immune cells to eliminate pathogens.
Vaccination introduces weakened or inactive pathogens to stimulate the immune response and provide immunity.
2.36 Respiration Provides the Energy for Life
Respiration is the process by which living organisms convert glucose into energy (ATP).
Aerobic respiration requires oxygen, while anaerobic respiration does not.
Respiration occurs in the mitochondria of cells.
The equation for aerobic respiration is:
2.37 Contraction of Muscles Requires Energy Supplied by Respiration
Muscle contraction requires energy in the form of ATP.
ATP is produced during respiration and is used to power the sliding of actin and myosin filaments in muscle cells.
Anaerobic respiration can also provide energy for muscle contraction, but it produces lactic acid as a byproduct, leading to muscle fatigue.
2.38 The Measurement of Respiration
Respiration rate can be measured by monitoring oxygen consumption or carbon dioxide production.
Respirometers are used to measure the rate of respiration in organisms or tissues.
Factors affecting respiration rate include temperature, oxygen availability, and activity level.
2.39 Gas Exchange Supplies Oxygen for Respiration
Gas exchange is the process by which oxygen is taken up from the environment and carbon dioxide is released.
In humans, gas exchange occurs in the lungs.
The alveoli in the lungs provide a large surface area for efficient gas exchange.
2.40 Breathing Ventilates the Lungs
Breathing is the process of moving air into and out of the lungs.
Inhalation is the active process of taking air into the lungs.
Exhalation is the passive process of releasing air from the lungs.
The diaphragm and intercostal muscles play a role in breathing.
2.41 Smoking and Disease
Smoking is a major risk factor for many diseases, including lung cancer, heart disease, and chronic obstructive pulmonary disease (COPD).
Smoking damages the lungs, blood vessels, and immune system.
Secondhand smoke is also harmful to non-smokers.
2.42 How Do We Know That Smoking Causes Disease?
Evidence linking smoking to disease comes from epidemiological studies, laboratory research, and clinical trials.
These studies have shown a strong correlation between smoking and the incidence of various diseases.
2.43 Excretion: Removal of the Waste Products of Metabolism
Excretion is the removal of metabolic waste products from the body.
The main excretory organs in humans are the kidneys, lungs, and skin.
The kidneys filter blood and produce urine, which contains urea, salts, and excess water.
2.44 Dialysis and the Treatment of Kidney Failure
Dialysis is a medical procedure used to filter blood when the kidneys are not functioning properly.
There are two types of dialysis: hemodialysis and peritoneal dialysis.
Kidney transplantation is another treatment option for kidney failure.
2.45 Homeostasis: Maintaining a Steady State
Homeostasis is the maintenance of a stable internal environment in the body.
It involves the regulation of temperature, water balance, blood glucose levels, and other factors.
Negative feedback mechanisms play a key role in homeostasis.
2.46 Control of Body Temperature
The body maintains a stable core temperature through thermoregulation.
Mechanisms for controlling body temperature include sweating, shivering, vasodilation, and vasoconstriction.
The hypothalamus in the brain is the main control center for thermoregulation.
2.47 Coordination: The Nervous System
The nervous system is responsible for coordinating and controlling bodily functions.
It consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves).
Neurons are the basic units of the nervous system.
2.48 Neurons Can Work Together in Reflex Arcs
Reflex arcs are neural pathways that control rapid, involuntary responses to stimuli.
A reflex arc typically involves a sensory neuron, an interneuron (in the spinal cord), and a motor neuron.
2.49 Integration by the Central Nervous System
The central nervous system (CNS) integrates information from the sensory organs and coordinates responses.
The brain is responsible for higher-level functions such as thought, memory, and emotion.
2.50 Receptors and Senses: The Eye as a Sense Organ
Sensory receptors are specialized cells that detect stimuli from the environment.
The eye is a complex sense organ that detects light and enables vision.
The retina contains photoreceptor cells (rods and cones) that convert light into electrical signals.
2.51 The Endocrine System
The endocrine system is a collection of glands that produce and secrete hormones.
Hormones are chemical
substances secreted into the bloodstream that affect target organs.
Hormones regulate various bodily functions, including growth, metabolism, and reproduction.
Examples of endocrine glands include the pituitary gland, thyroid gland, adrenal glands, and pancreas.
2.52 Drugs and Disorders of the Nervous System
Drugs can affect the nervous system by altering neurotransmitter activity or disrupting neuronal function.
Some drugs, such as stimulants, increase neuronal activity, while others, such as depressants, decrease neuronal activity.
Disorders of the nervous system include Alzheimer's disease, Parkinson's disease, and multiple sclerosis.
2.53 Sensitivity and Movement in Plants: Tropisms
Plants respond to environmental stimuli through tropisms.
Tropisms are directional growth responses to stimuli such as light (phototropism), gravity (geotropism), and water (hydrotropism).
Auxins are plant hormones that regulate tropisms.
3 Development of Organisms and the Continuity of Life
3.1 Reproduction Is an Important Characteristic of Living Organisms
Reproduction is the process by which living organisms produce offspring.
There are two main types of reproduction: sexual reproduction and asexual reproduction.
Sexual reproduction involves the fusion of gametes (sex cells) from two parents, resulting in genetic variation in the offspring.
Asexual reproduction involves a single parent and produces offspring that are genetically identical to the parent.
3.2 Reproduction in Flowering Plants: Flowers
Flowers are the reproductive structures of flowering plants (angiosperms).
Flowers contain male reproductive organs (stamens) and female reproductive organs (carpels).
The stamen consists of a filament and an anther, which produces pollen grains containing male gametes.
The carpel consists of an ovary, style, and stigma, which receives pollen grains.
3.3 Pollination: The Transfer of Male Sex Cells to Female Flower Parts
Pollination is the transfer of pollen grains from the anther to the stigma.
Pollination can occur through wind, water, insects, birds, or other animals.
Cross-pollination involves the transfer of pollen from one plant to another, promoting genetic diversity.
3.4 Fertilisation and the Formation of Seed and Fruit
Fertilization is the fusion of a male gamete (sperm) from a pollen grain with a female gamete (egg) in the ovule.
Fertilization results in the formation of a zygote, which develops into an embryo.
The ovule develops into a seed, and the ovary develops into a fruit.
3.5 Germination of Seeds
Germination is the process by which a seed sprouts and begins to grow into a new plant.
Germination requires water, oxygen, and a suitable temperature.
The radicle (embryonic root) emerges first, followed by the plumule (embryonic shoot).
3.6 Reproduction in Humans
Human reproduction is sexual and involves the fusion of male and female gametes.
The male reproductive system consists of the testes, epididymis, vas deferens, seminal vesicles, prostate gland, and penis.
The female reproductive system consists of the ovaries, fallopian tubes, uterus, cervix, and vagina.
3.7 The Menstrual Cycle
The menstrual cycle is a recurring series of events in the female reproductive system that prepares the body for pregnancy.
The menstrual cycle typically lasts about 28 days and involves changes in hormone levels and the uterine lining.
The main phases of the menstrual cycle are menstruation, the follicular phase, ovulation, and the luteal phase.
3.8 Copulation and Conception
Copulation (sexual intercourse) is the process by which sperm are deposited into the female reproductive tract.
Conception (fertilization) occurs when a sperm fuses with an egg in the fallopian tube.
The resulting zygote begins to divide and implant in the uterine lining.
3.9 Contraception
Contraception is the prevention of pregnancy.
Methods of contraception include barrier methods (e.g., condoms), hormonal methods (e.g., birth control pills), intrauterine devices (IUDs), and surgical methods (e.g., vasectomy, tubal ligation).
3.10 Pregnancy: The Role of the Placenta
Pregnancy is the period during which a developing embryo or fetus is carried in the uterus.
The placenta is an organ that provides nutrients and oxygen to the fetus and removes waste products.
The placenta is connected to the fetus by the umbilical cord.
3.11 Pregnancy: Development and Antenatal Care
Prenatal development involves rapid growth and differentiation of the embryo and fetus.
Antenatal care includes regular checkups, screening tests, and advice on nutrition and lifestyle to ensure a healthy pregnancy.
3.12 Birth and the Newborn Baby
Birth (parturition) is the process by which the fetus is expelled from the uterus.
Labor involves contractions of the uterine muscles that dilate the cervix and push the baby through the birth canal.
The newborn baby requires care and attention, including feeding, warmth, and hygiene.
3.13 Sexually Transmitted Infections
Sexually transmitted infections (STIs) are infections that are spread through sexual contact.
Examples of STIs include chlamydia, gonorrhea, syphilis, herpes, and HIV.
STIs can be prevented by practicing safe sex, including using condoms and getting tested regularly.
3.14 Variation and Inheritance
Variation is the differences between individuals in a population.
Inheritance is the transmission of genetic information from parents to offspring.
Genes are units of inheritance that determine traits.
3.15 DNA, Proteins and the Characteristics of Organisms
DNA (deoxyribonucleic acid) is the molecule that carries genetic information in living organisms.
Genes are segments of DNA that code for proteins.
Proteins are responsible for the structure and function of cells and organisms.
3.16 How the Code Is Carried
The genetic code is carried in the sequence of nucleotide bases in DNA.
DNA consists of four nucleotide bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
The sequence of these bases determines the sequence of amino acids in a protein.
3.17 Cell Division
Cell division is the process by which cells reproduce.
There are two main types of cell division: mitosis and meiosis.
Mitosis produces two identical daughter cells and is used for growth and repair.
Meiosis produces four genetically different daughter cells and is used for sexual reproduction.
3.18 Inheritance
Inheritance is the transmission of genetic information from parents to offspring.
Genes are units of inheritance that determine traits.
Alleles are different forms of a gene.
3.19 Studying Patterns of Inheritance
Patterns of inheritance can be studied using Punnett squares and pedigree analysis.
Punnett squares are used to predict the genotypes and phenotypes of offspring based on the genotypes of the parents.
Pedigree analysis is used to trace the inheritance of traits through multiple generations of a family.
3.20 Inherited Medical Conditions and Codominance
Some medical conditions are inherited due to genetic mutations.
Examples of inherited medical conditions include cystic fibrosis, sickle cell anemia, and hemophilia.
Codominance is a pattern of inheritance in which both alleles of a gene are expressed in the heterozygote.
3.21 Sex Is Determined by X and Y Chromosomes
Sex is determined by the X and Y chromosomes.
Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
The Y chromosome carries the SRY gene, which determines maleness.
3.22 Variation
Variation is the differences between individuals in a population.
Variation can be caused by genetic factors, environmental factors, or a combination of both.
3.23 Causes of Variation
Genetic variation can be caused by mutations, gene flow, and sexual reproduction.
Environmental variation can be caused by differences in climate, nutrition, and exposure to toxins.
3.24 Variation and Natural Selection: The Evolution of Species
Natural selection is the process by which organisms with advantageous traits are more likely to survive and reproduce.
Natural selection leads to the evolution of species over time.
3.25 Natural Selection
Natural selection requires variation, inheritance, and differential reproductive success.
Organisms with traits that make them better adapted to their environment are more likely to survive and reproduce.
3.26 Artificial Selection
Artificial selection is the process by which humans selectively breed organisms with desirable traits.
Artificial selection can lead to rapid changes in the characteristics of a population.
4 Organisms and Their Environment
4.1 Ecology and Ecosystems
Ecology is the study of the interactions between organisms and their environment.
An ecosystem is a community of living organisms and their physical environment.
4.2 Flow of Energy: Food Chains and Food Webs
Energy flows through ecosystems through food chains and food webs.
A food chain is a linear sequence of organisms in which each organism feeds on the one below it.
A food web is a complex network of interconnected food chains.
4.3 Feeding Relationships: Pyramids of Numbers, Biomass and Energy
Feeding relationships in ecosystems can be represented by pyramids of numbers, biomass, and energy.
A pyramid of numbers shows the number of organisms at each trophic level.
A pyramid of biomass shows the total mass of organisms at each trophic level.
A pyramid of energy shows the amount of energy at each trophic level.
4.4 Decay Is a Natural Process
Decay is the breakdown of dead organisms and organic matter by decomposers.
Decomposers include bacteria and fungi.
Decay releases nutrients back into the ecosystem.
4.5 The Carbon Cycle
The carbon cycle is the biogeochemical cycle that describes the movement of carbon through the environment.
Carbon is transferred between the atmosphere, land, and oceans through processes such as photosynthesis, respiration, and decomposition.
4.6 The Nitrogen Cycle
The nitrogen cycle is the biogeochemical cycle that describes the movement of nitrogen through the environment.
Nitrogen is an essential nutrient for plant growth.
Nitrogen is converted into different forms by bacteria in the soil.
4.7 Water Is Recycled Too!
Water is recycled through the water cycle.
The water cycle involves evaporation, transpiration, condensation, and precipitation.
4.8 Factors Affecting Population Size
Population size is affected by birth rate, death rate, immigration, and emigration.
Limiting factors such as food availability, water, and space can restrict population growth.
4.9 Human Population Growth
The human population has been growing exponentially in recent centuries.
Human population growth has led to environmental problems such as deforestation, pollution, and climate change.
4.10 Bacteria Are Useful in Biotechnology and Genetic Engineering
Bacteria are used in biotechnology and genetic engineering for various purposes.
Bacteria can be used to produce antibiotics, enzymes, and other useful products.
4.11 Humans Use Enzymes from Bacteria
Enzymes from bacteria are used in various industrial processes.
Examples include the use of bacterial enzymes in the production of cheese, yogurt, and detergents.
4.12 Using Fungi to Produce Antibiotics: Drugs to Control Bacterial Disease
Fungi are used to produce antibiotics, which are drugs that kill or inhibit the growth of bacteria.
Penicillin is an antibiotic produced by the fungus Penicillium.
4.13 Baking and Brewing: The Economic Importance of Yeast
Yeast is used in baking and brewing.
Yeast produces carbon dioxide, which makes bread rise.
Yeast produces alcohol during fermentation, which is used to make beer and wine.
4.14 Genetic Engineering
Genetic engineering is the process of altering the genetic material of an organism.
Genetic engineering can be used to produce crops that are resistant to pests and diseases.
4.15 Food Supply: Humans and Agriculture
Humans depend on agriculture for their food supply.
Agriculture has allowed humans to produce large quantities of food and support large populations.
4.16 Land Use for Agriculture
Land is used for agriculture to grow crops and raise livestock.
Land use for agriculture can have environmental impacts such as deforestation, soil erosion, and water pollution.
4.17 Damage to Ecosystems: Malnutrition and Famine
Damage to ecosystems can lead to malnutrition and famine.
Deforestation, soil erosion, and water pollution can reduce crop yields and lead to food shortages.
4.18 Human Impacts on the Environment: Pollution
Human activities have various impacts on the environment, including pollution.
Pollution can be caused by industrial processes, agriculture, and transportation.
4.19 Pollution of Water: Eutrophication
Eutrophication is the enrichment of water with nutrients, leading to excessive growth of algae and depletion of oxygen.
Eutrophication can be caused by agricultural runoff and sewage discharge.
4.20 Humans May Have a Positive Effect on the Environment: Conservation of Species
Humans can have a positive effect on the environment through conservation efforts.
Conservation efforts can help to protect endangered species and preserve biodiversity.
4.21 Managing Fish Stocks: Science and the Fishing Industry
Fish stocks need to be managed sustainably to ensure that they are not overfished.
Science plays a role in managing fish stocks by providing information on fish populations and their habitats.
4.22 Conservation Efforts Worldwide
Conservation efforts are being carried out worldwide to protect endangered species and preserve biodiversity.
Examples include the establishment of national parks and wildlife reserves.
4.23 Conservation of Resources: Recycling Water by the Treatment of Sewage
Resources can be conserved through recycling.
Water can be recycled by treating sewage and using it for irrigation or industrial purposes.
4.24 Saving Fossil Fuels: Fuel from Fermentation
Fossil fuels can be saved by using alternative
4.24 Saving Fossil Fuels: Fuel from Fermentation
Fossil fuels can be saved by using alternative fuels such as ethanol, which is produced by fermentation.
4.25 Recycling: Management of Solid Waste
Solid waste can be managed through recycling.
Recycling involves collecting and processing waste materials to produce new products.