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Importance of Biodiversity
Last Updated: September 18, 2023Learning objectives: Kingdom Plantae Diagnostic features of the Kingdom Plantae Economic importance of kingdom plantae Kingdom Animaliae Diagnostic features of the kingdom Animaliae Economic importance of kingdom animalia Kingdom Prokaryotae Diagnostic features of the kingdom Prokaryotae Economic importance of bacteria-prokaryotae Kingdom Fungi Diagnostic features of the Kingdom Fungi Economic importance of fungi Kingdom Protoctista Protozoa...
Biodiversity Classification
Last Updated: September 18, 2023Learning objectives Introduction Hierarchy of classification Terminology Binomial nomenclature The taxonomic hierarchy Specimen identification and keys The Five kingdoms Advantages of Five Kingdom Classification
C4 photosynthesis | C4 Plants
Last Updated: September 18, 2023The Hatch-Slack Pathway Key Terms Differences Mesophyll Chloroplasts Bundle Sheath Chloroplasts Size of Grana Large No grana or very few and small Light-dependent reactions Favored, plenty of ATP, reduced NADP, and O2 Occur at very low rate, little ATP, NADP, or O2 RuBP Carboxylase Virtually no presence High concentration CO2 Fixation Occurs in cytoplasm by...
Conservation and biodiversity
Last Updated: September 17, 2023Conservation Biodiversity The Need to maintain Biodiversity Biological reasons Human reasons Other species of animals and plants provide an important resource for humans. These may be Reasons why species have become endangered Habitat loss Hunting Poaching Habitat loss Methods of protecting endangered species Zoos Captive Breeding Captive breeding has a number of advantages: Although some...
Anthropogenic Impact on Ecosystems
Last Updated: September 17, 2023How fossil fuels may affect the environment Smoke sulphur dioxide Carbon dioxide Carbon monoxide. Nitrogen oxides The use and effects of nitrogen containing fertilizers in agriculture. Lead Methods of controlling air pollution. The effects of deforestation to the environment Measures
The Nitrogen cycle
Last Updated: September 17, 2023The Nitrogen cycle Nitrogen fixation Nitrification Questions and model answers Describe the role played by microorganisms in the Nitrogen cycle [6] Emphasis should have been placed on specific organisms and the part they play in the Nitrogen cycle. Explain the role of nitrifying bacteria and denitrifying bacteria in the Nitrogen Cycle. Decay and Ammonification. Animals...
Levels of Ecological Organisation
Last Updated: September 17, 2023Ecology is the study of organism within their environment, including the way in which organisms interact with each other & the non-living part of the environment Terms used in ecology 1. Habitant 2. Population 3. Community 4. Ecosystem. 5. Niche Flow of energy Grazing food chain Detrital food chain Food web Parasitic food chain Questions...
The Cell cycle
Last Updated: September 17, 2023The cycle is divided into four distinct phases, G1, S, G2, and M (mitosis). Interphase G1 phase S phase G2 phase The mitotic phase Mitosis Phases Reductional division Meiosis is composed of two distinctive cell divisions, meiosis I and meiosis II. The first division The second division Overview of meiosis. The Cell Cycle questions and answers
Nervous System | Need for communication
Last Updated: September 17, 2023Learning objectives The need for communication within living organisms Action potentials | Transmission of action potentials Synaptic Transmission
Action potentials | Transmission of action potentials
Last Updated: September 17, 2023Action potentials Refractory period period of time where the axon is unresponsive, recovering from an action potential (restoring its resting potential). It can be absolute or relative refractory period Transmission of action potentials Once action potential has been set up, it moves rapidly from one end of the neuron to the other. This happens because...
Synapses and Synaptic Transmission
Last Updated: July 10, 2026Synapses A synapse is the specialized junction between two neurons or between a neuron and an effector (a muscle or gland). It allows nerve impulses to be transmitted from one cell to another through either chemical or electrical signaling. A typical chemical synapse consists of: Remember: Most synapses in humans are chemical synapses. Properties and...
The light-independent stage l Calvin cycle
Last Updated: September 17, 2023The light-independent stage Reactions of the Calvin Cycle Practice questions Outline/ describe the main features/reactions of the Calvin Cycle. Photosynthesis questions and answers
Respiratory quotient (RQ)
Last Updated: September 17, 2023Respiratory Substrates Energy values of respiratory substrates The energy value of a substrate is determined by burning a known mass of the substrate in oxygen in a calorimeter. Respiratory quotient (RQ) Examples of RQ values for different respiratory substrates
ATP Structure and Synthesis
Last Updated: September 18, 2023The need for energy in living organisms Energy is needed for several processes in the body, including: The universal energy currency in all living organisms. The structure and synthesis of ATP Adenosine (a nucleoside) can be combined with one, two or three phosphate groups Metabolism All the biochemical reactions needed for an organism to stay...
The Electron Transport Chain
Last Updated: September 17, 2023Introduction The Electron Transport Chain The electron transport chain is the final stage of cellular respiration, responsible for the production of ATP (adenosine triphosphate) and the formation of water molecules. Key points of the electron transport chain Practice question
Introduction to HHD
Last Updated: September 16, 2023Describe whether health is more than simply the absence of a disease Outline the aspects that contribute towards good health Disease Categories of diseases Question: using named examples for each, explain what is meant by degenerative and inherited disease. Degenerative Mental self-inflicted non-infectious Epidemiology and patterns of diseases Epidemic Endemic Pandemic Prevalence Incidence Epidemiology
Drug abuse
Last Updated: September 16, 2023Drugs Distinguish between physical and psychological dependence on drugs Physical Psychological Withdrawal symptoms How you might tell whether a drug is socially acceptable or not Factors that contribute to drug dependence Drug tolerance and why it occurs with heroin Heroin Why the use of heroin can result in damage to health Effects of heroin...
Alcohol abuse
Last Updated: September 16, 2023Alcohol tolerance Metabolism of alcohol Long term consequences of alcohol consumption on the liver, brain and peripheral nervous system Liver Brain Peripheral nervous system Short term effects of alcohol consumption on the brain Social problems associated with heavy alcohol drinking
Gaseous exchange
Last Updated: September 16, 2023Pathway taken by an oxygen molecule as it passes from the atmosphere to the blood in the lungs Mouth/nostrils, nasal passage, larynx, trachea, bronchus, terminal and respiratory bronchioles, alveolar duct, alveolus, epithelium, connective tissues, endothelium of capillary, plasma, red blood cells Trachea Smooth muscles Elastic fibre Cartilage Goblet cells Bronchioles Alveolus Adaptations of the alveolus...
Smoking and diseases
Last Updated: September 16, 2023Effects of tar in tobacco smoke on the gaseous exchange system Effects of tar and carcinogens in tobacco smoke on the gaseous exchange system The effects of nicotine and carbon monoxide on the cardiovascular system Nicotine Carbon monoxide Describe how atherosclerosis develops. Explain how atherosclerosis may lead to death Link between atherosclerosis and coronary heart...
Chemotherapy and antibiotics
Last Updated: September 16, 2023Chemotherapy Antibiotics Mode of action of antibiotics although there are a number of different types of antibiotic they all work in one of two ways: Broad spectrum and narrow spectrum antibiotics Narrow spectrum antibiotics Advantages of narrow spectrum antibiotics Disadvantages of narrow spectrum antibiotics: Broad spectrum antibiotics Selection of antibiotics Advantages and limitations of using...
Cholera
Last Updated: September 16, 2023Signs and symptoms of cholera Common symptoms of cholera and the dehydration it causes include: Transmission of cholera Describe how cholera can be spread from one person to another/ Explain how cholera is transmitted from one person to another through water supply/ Describe and explain the ways through which cholera is transmitted Global distribution of...
Malaria
Last Updated: September 16, 2023Introduction Malaria is a mosquito-borne infectious disease that affects humans and other vertebrates. Human malaria causes symptoms that typically include fever, fatigue, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death1. Symptoms usually begin 10 to 15 days after being bitten by an infected mosquito. Malaria is caused by single-celled microorganisms of the Plasmodium...
Tuberculosis
Last Updated: September 16, 2023Causes of TB Signs and symptoms of TB Most people who become infected with Mycobacterium tuberculosis do not present symptoms of the disease. However, when symptoms are present, they include: Symptoms specific to the lungs include: Transmission of TB People at risk Although anyone can be exposed to or get TB, some people are at...
HIV/AIDS
Last Updated: September 16, 2023Acquired Immunodeficiency syndrome (AIDS) Structure of the HIV virus Transmission Viral Replication/Multiplication HIV and Immunity HIV infection progression – the phases of HIV infection include; 1. HIV Infection 2. Window period 3. Seroconversion (antibody – positive phase/ HIV-positive phase) 4. Asymptomatic HIV 5. HIV related illnesses (AIDS –related complex) 6. AIDS Factors that affect...
Immunity Allergies
Last Updated: September 16, 2023Hay fever Symptoms Cause Treatment – Treatment of an allergic reaction involves avoiding the allergen as far as possible and preventing or treating the symptoms. Asthma Cause The allergens that commonly cause asthma are: Symptoms:
Active and passive immunity
Last Updated: September 16, 2023Active immunity Passive immunity Natural Artificial How vaccination give protection against diseases Describe why vaccination managed to eradicate small pox but not malaria Small pox Malaria Measles Tuberculosis Cholera
Immunity notes
Last Updated: September 16, 2023(i)The non-specific system (ii)The specific system Non-specific system Specific Immune system Primary defence against disease Surface barriers Defence mechanism Function Skin Prevents entry of pathogens and foreign substances Acid secretions Inhibit bacterial growth on skin Mucus Prevents entry of pathogens, mucous membranes also produce defensins (small toxic peptides) that kill pathogens Nasal hairs Filter bacteria...
Cells of the Immune system
Last Updated: September 16, 2023Phagocytes Types of phagocytes Neutrophil The cell with the lobed nucleus [in the centre] is a neutrophill; a type of a phagocyte. Monocyte The cell with a horseshoe-shaped nucleus is a monocyte; from the family of phagocytes. Lymphocytes The cell with a uniformly circular nucleus is a lymphocyte; it can either by a B-lymphocyte or...
Lipids
Last Updated: August 30, 2023Describe the molecular structures of a triglyceride and a phospholipid. Triglyceride structure Phospholipid structure Explain how the molecular structure of triglycerides is related to their functions.[8] Describe with examples the roles of lipids in an organism. [6] Relate the structures of triglycerides and phospholipids to their functions in living organisms. Triglyceride structure and function Phospholipid...
Proteins and enzymes
Last Updated: August 30, 2023Explain how DNA structure determines the specific shape of enzymes.[8] Difference between globular proteins and Fibrous proteins[8] GLOBULAR PROTEIN FIBROUS PROTEINS It has polypeptide chains with irregular sequence of amino acids It has polypeptide chains with regular repetitive sequences of amino acids Its shape is a compact globule of polypeptides It has long chins running...
Drug and substance abuse
Last Updated: August 30, 2023Describe the events in the development of lung cancer[8] Describe how emphysema and chronic bronchitis affects the gaseous exchange system[8] Discuss the short term effects of physical exercise on muscles and gaseous exchange[8] Effects of tar in tobacco smoke on the gaseous exchange system[8] Effects of tar and carcinogens in tobacco smoke on the gaseous...
Immunity
Last Updated: August 30, 2023Describe the origin, maturation and mode of action of phagocytes Describe two types of phagocyte: Distinguish between B- and T-lymphocytes in their mode of action in fighting infection, and describe their origin and functions Distinguish between phagocytes and lymphocytes Phagocytes Lymphocytes macrophages and neutrophils B and T cells involved in non-specific response/engulfing the bacteria/pathogen/antigen involved...
Global distribution of Diseases
Last Updated: August 30, 2023Outline the aspects that contribute towards good health[6] Discuss the possible reasons for the global distribution of coronary heart diseases[6] Explain the possible reasons for the global distribution of TB[8] Explain the possible reasons for the global distribution of measles[8] Explain the possible reasons for the global distribution of HIV/AIDS[8] How cigarette smoking can lead...
Sexual Reproduction in Plants
Last Updated: August 30, 2023Structure and Pollen Formation Stages Ovule Development Double Fertilization Steps Significance of Double Fertilization Describe the structural changes that occur after fertilisation, leading to the development of the seed and fruit. Gametogenesis in Plants State the structural features that are characteristic of a wind-pollinated flower and explain how each feature contributes to successful pollination.
Sexual Reproduction in Humans
Last Updated: August 30, 2023Describe differences between spermatogenesis and oogenesis in humans. spermatogenesis oogenesis Continuous after puberty, In cycles after puberty; Millions produced, One/few per cycle; Occurs 12-65+, 9 –menopause/40; 4 sperm , 1 ovum per meiosis; No, Polar bodies; All mitotic products used many mitotic products degenerate/less mitotic replication; Complete meiosis on release, Completes meiosis after ovulation/AW; Primary...
Natural and artificial selection
Last Updated: August 30, 2023Describe the role of natural selection in evolution. [8] ZIMSEC June 2014/2/12(a) Explain how natural selection may bring about evolution. [8] Describe why variation is important in natural selection. [6] Explain the role of isolating mechanisms in the evolution of new species. [8] Explain, using named examples, how mutation can affect phenotype. [8] ZIMSEC June...
Biodiversity Classification
Last Updated: August 29, 2023Introduction Hierarchy of classification Terminology used. Taxonomic Hierarchy Example The classification of humans Binomial nomenclature The taxonomic hierarchy Multiple choice questions 1.Which of the following taxonomic levels is the most specific and represents a group of organisms capable of interbreeding and producing fertile offspring?a) Kingdomb) Familyc) Genusd) Class 2. In the scientific name “Canis lupus,”...
Biodiversity
Last Updated: August 29, 2023Classification and Importance of Biodiversity Diagnostic features of the Kingdom Plantae[8] Economic importance of kingdom plantae[6] Diagnostic features of the kingdom Animaliae[8] Economic importance of kingdom animalia[6] Diagnostic features of the kingdom Prokaryotae[8] Economic importance of bacteria-prokaryotae [6] Diagnostic features of the Kingdom Fungi[6] Economic importance of fungi[6] Bacteria are members of the kingdom Prokaryota....
Anthropogenic Impact on Ecosystems
Last Updated: August 29, 2023Describe how deforestation may affect the environment [6] [ZIMSEC June 2003/2/10(b)] Effects of Human Activities on Ecosystems Human activities have profoundly impacted ecosystems worldwide, altering natural processes and threatening biodiversity. Human Settlement Deforestation Industrial Activities Agricultural Activities Mining Global Warming Invasive Plant Species Human activities have significant and often detrimental effects on ecosystems. The resulting...
Conservation
Last Updated: August 29, 2023Conservation Strategies: Preservation Management Reclamation Role of Environmental Management Agency (EMA) Environmental Impact Assessments (EIAs) Enforcement and Regulation: Public Awareness and Education: Role of CAMPFIRE Community-Based Natural Resource Management Benefits of CAMPFIRE Outline the reasons why conservationists are concerned about the population of the African elephant,loxodonta Africana. [8] [ZIMSEC November 2014/2/9(b)] Discus the conservation of...
Ecological Organization & Nitrogen cycle
Last Updated: August 29, 2023Describe how energy flows in an ecosystem [8] [ZIMSEC November 2003/2/13(a)] Explain the role of nitrifying bacteria and denitrifying bacteria in the Nitrogen Cycle[8]. Describe the role played by microorganisms in the nitrogen cycle [6] [ZIMSEC June 2003/2/10(a)] Discuss the use and effects of nitrogen containing fertilizers in agriculture. [8] [ZIMSEC November 2014/2/9(a)]
Nervous Control
Last Updated: August 29, 2023Explain the roles of synapses in the nervous system. [6] Describe the structure of a myelinated sensory neurone.[8] Describe the structure of a myelin sheath and explain its role in the speed of transmission of a nerve impulse. [8] How an action potential is transmitted along myelinated neurone[6] [ZIMSEC June j2004/2/13(a)] Describe the role of...
Cancer
Last Updated: September 17, 2023Cancer and uncontrolled cell division The stages involved in the development of cancer
The Cell Cycle
Last Updated: August 29, 2023Stages of The Cell cycle Interphase G1-phase (Gap 1 phase) S-phase (Synthesis phase) G2-phase (Gap 2 phase) Miotic phase (M-phase) Mitosis in Pig Kidney Epithelial Cells Cc: www.microscopyu.com Multiple choice questions Which cyclin-CDK (cyclin-dependent kinase) complex is primarily responsible for driving the cell from G1 phase into the S phase of the cell cycle?A) Cyclin...
Mitosis
Last Updated: September 18, 2023is a nuclear division giving rise to genetically identical cells in which the chromosome number is maintained by the exact duplication of chromosome. Stages of Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis Is the actual division of the cytoplasm to form two daughter cells Explain the significance of mitosis[8] Outline the differences between mitosis and meiosis[8]...
Meiosis
Last Updated: August 29, 2023Describe the behavior of chromosomes during meiosis. [8] Describe how genetic variation in secondary oocytes arises. Describe the first division of meiosis (meiosis I) in animal cells. [6] Describe how crossing over and independent assortment can lead to genetic variation.[8] Explain how meiosis and fertilization can result in genetic variation amongst offspring. [8] Explain how...
Gene Technology
Last Updated: August 28, 2023Describe the use of recombinant DNA technology in the synthesis of human insulin by bacteria [8] Describe how the gene coding for human insulin can be obtained and inserted into a plasmid vector. [8] Explain the advantages of treating diabetic people with human insulin produced by gene technology.[6] Explain how bacteria can be genetically modified...
Transport in plants
Last Updated: August 30, 2023Relate the structure of the xylem to its function [6] Describe how the structure of the xylem vessels is adapted for their function of transporting water up the stem[6] ZIMSEC November 2008/2/12(a)] Sclerenchyma With reference to the structure of a leaf, explain the difference between evaporation and transpiration. evporation transpiration formation of water vapour from...
Transport in mammals
Last Updated: August 30, 2023Describe how the structure of arteries and capillaries is related to their function.[8] Relate the structure of the artery to its function[6] Describe how the heart is controlled[8] With reference to the structures and tissues within the heart, describe how the cardiac cycle is initiated and coordinated. Describe how the heart is initiated[8] ZIMSEC November...
Respiration
Last Updated: August 28, 2023Relate the structure of a mitochondriion to it’s funtion[6] Describe how the structure of a mitochondrion is related to its function. [8] Outline the process of anaerobic respiration in both mammal and yeast cells. [8] Explain how the reduced NAD is oxidised under anaerobic conditions in mammalian muscle tissue and in yeast.[6] Explain the role...
Photosynthesis
Last Updated: September 17, 2023Describe the structure of a chloroplast. [8] Relate the structure of the chloroplast to their roles in photosynthesis. [7][ZIMSEC November 2014/2/11(a) Explain how the palisade mesophyll cells of a leaf are adapted for photosynthesis. [8][ZIMSEC November 2015/2/12(b)] Describe the arrangement and location of chloroplast pigments and discuss their effect on absorption spectra. [8] Describe the...
ATP structure and synthesis
Last Updated: August 28, 2023Outline the need for energy in living organisms[6] Explain the different energy values of carbohydrate, lipid and protein as respiratory substrates. [6] Describe the structure and synthesis of ATP and its universal role as the energy currency in all living organisms. [8][ZIMSEC June 2017/2/11(b)] Explain the role of ATP in active transport of ions and...
Genetic Screening and Fingerprinting
Last Updated: August 29, 2023Describe how genetic screening is carried out Genetic screening is a process used to identify individuals who carry certain genetic traits or mutations associated with genetic disorders or conditions. It involves analyzing an individual’s DNA to detect specific genetic variations. Here’s how genetic screening is carried out: 1.Sample Collection: The first step involves obtaining a...