JK-TK/Newdata huggingface dataset:
They have adaptations to reduce the rate of transpiration in order to save on water consumption. Others have water storage structures. Adaptations include:
Reduction of leaf surface area by having needle-like leaves, rolling up of leaves and shedding of leaves during drought to reduce water loss or transpiration. Thick cuticle; epidermis consisting of several layers of cells;
leaves covered with wax or resin to reduce evaporation. Sunken stomata, creating spaces with humid still air to reduce water holes. Few, small stomata, on lower epidermis to reduce water loss. Stomata open at night (reversed stomatal rhythm) to reduce water loss . Deep and extensive root systems for absorption of water. Development of flattened shoots and succulent tissue for water storage e.g. Opuntia. Mesophytes
These are the ordinary land plants which grow in well-watered habitats. They have no special adaptations. Stomata are found on both upper and lower leaf surfaces for efficient gaseous exchange and transpiration. However, those found in constantly wet places e.g. tropical rain forests, have features that increase transpiration. These plants are called hygrophytes. The leaves are broad to increase surface areas for transpiration and thin to ensure short distance for carbon (IV) oxide to reach photosynthetic cells and for light penetration. The stomata are raised above the epidermis to increase the rate of transpiration. They have grandular hairs or byhathodes that expel water into the saturated atmosphere. This phenomenon is called guttation. Hydrophytes (Water plants)
Water plants are either submerged, emergent or floating. Submerged Plants
The leaves have an epidermis with very thin walls and a delicate cuticle. They have no stomata. Water is excreted from special glands and pores at the tips. Other adaptations include the following:
Presence of large air spaces and canals (aerenchyma) for gaseous exchange and buoyancy. Some plants have filamentous leaves In order to increase the surface area for absorption of light, gases and mineral salts. Some plants are rootless, hence support provided by water. Mineral salts and water absorbed by all plant surfaces. In some plants, the stem and leaves are covered with a waxy substance to reduce absorption of water. e.g. Ceratophyllum and Elodea sp. Floating Plants
Their structure is similar to that of mesophytes.
e.g. Ceratophyllum and Elodea sp. Floating Plants
Their structure is similar to that of mesophytes. The leaves are broad to increase the surface area for water loss. They have more stomata on the upper surface than on the lower surface to increase rate of water loss. Examples are Pistia sp. (water lettuce), Salvinia and Nymphea. Halophytes (Salt plants)
These are plants that grow in salt marshes and on coastlines. They have root cells that concentrate salts and enable them to take in water by osmosis. They have salt glands which excrete salts. Fruits have large aerenchymatous tissues for air storage that makes them float. Some have shiny leaves to reduce water loss. The mangrove plants have roots that spread horizontally, and send some branches into the air. These aerial roots are known as breathing roots or pneumatophores. They have lenticel-Iike openings called pneumatothodes through which gaseous exchange takes place. Pollution
Effect of Pollution on Human Beings and other Organisms
Pollution
This is the introduction of foreign material, poisonous compounds and excess nutrients or energy to the environment in harmful proportions. Any such substance is called a pollutant. Effects and Control of causes of Pollutants in Air, Water and Soil
Industrialisation and urbanisation are the main causes of pollution. As human beings exploit natural resources the delicate balance in the biosphere gets disturbed. The disturbance leads to the creation of conditions that are un-favourable to humans and other organisms. Sources of Pollutants
Motor vehicles release carbon (II) oxide, sulphur (IV) oxide, and nitrogen oxides and hydrocarbons. Agricultural chemicals, fertilisers and pesticides. Factories, manufacturing and metal processing industries. They release toxic substances and gases as well as synthetic compounds that are bio-undegradable. They release solid particles or droplets of poisonous substances e.g. arsenic, beryllium, lead and cadmium. Radioactive waste: Leakages from nuclear power stations and testing sites release radioactive elements like strontium-90 which can eventually reach man through the food chain. Domestic waste and sewage are released raw into water bodies. Oil spills from accidents in the seas and leakage of oil tankers as well as from offshore drilling and storage and processing. Water Pollution. In most cases, chex,pical wastes from industries are discharged into water.
Oil spills from accidents in the seas and leakage of oil tankers as well as from offshore drilling and storage and processing. Water Pollution. In most cases, chex,pical wastes from industries are discharged into water. Toxic chemicals such as mercury compounds may be ingested by organisms. Insecticides like DDT, and weedkillers eventually get into the water and contaminate it. Oil and detergents also pollute water. Excess nitrates and phosphates from sewage and fertilisers cause overgrowth of algae and bacteria in water. This is called eutrophication. As a result there is insufficient oxygen which causes the deaths of animals in the water. Air pollution:
Smoke from industries and motor vehicles contains poisonous chemicals like carbon (II) oxide, carbon (IV) oxide, sulphur (IV) oxide and oxides of nitrogen. When sulphur (IV) oxide and oxides of nitrogen dissolve in rain, they fall as acid rain. Accumulation of carbon (IV) oxide in the atmosphere causes the infrared light to be confined within the atmosphere, the earth's temperature rises. This is called the greenhouse effect. Carbon particles in smoke coat the leaves of plants and hinder gaseous exchange and photosynthesis. The particles also form smog in the air. Lead compounds are from vehicle exhaust pipes. All these have negative effects on man and the environment. Soil/Land pollution:
Plastics and other man-made materials are biologically non-degradable i.e they are not acted upon by micro-organisms. Scrap metal and slag from mines also pollute land. Failure to rehabilitate mines and quarries also pollute land. Effects of Pollutants to Humans and other organisms
Chemical pollutants e.g. nitrogen oxides, fluorides, mercury and lead cause physiological and metabolic disorders to humans and domestic animals. Some hydrocarbons as well as radioactive pollutants acts as mutagens (cause mutations) and carcinogens induce cancer. Radioactive pollutants like strontium, caesium and lithium are absorbed into body surface and cause harm to bone marrow and the thyroid gland. Communicable diseases like cholera are spread through water polluted with sewage. Thermal pollution result in death of some fish due to decreased oxygen in the water. Oil spills disrupt normal functioning of coastal ecosystems. Birds that eat fish die due to inability to fly as feathers get covered by oil. Molluscs and crustaceans on rocky shores also die.
Oil spills disrupt normal functioning of coastal ecosystems. Birds that eat fish die due to inability to fly as feathers get covered by oil. Molluscs and crustaceans on rocky shores also die. Control of Air Pollution
Use of lead-free petrol and low sulphur diesel in vehicles. Use of smokeless fuels e.g electricity or solar. Filtration of waste gases to remove harmful gases. Liquid dissolution of waste gases. In Kenya, factories are subjected to thorough audits to ensure that they do not pollute the environment. Factories should be erected far away from residential areas. Reduce volume or intensity of sound. Use of ear muffs. Vehicle exhaust systems should be fitted with catalytic oxidisers. Regular servicing of vehicles to ensure complete combustion of fuel. Water Pollution
Treatment of sewage. Treatment of industrial waste before discharge into water. Use of controlled amounts of agrochemicals. Organic farming and biological control. Avoid spillage of oils and other chemicals into water. Good water management. Stiff penalties for oil spillage. Use of Pseudomonas bacteria that naturally feed on oil and break it up. Soil Pollution
Addition of lime to farms to counteract the effect of agrochemicals. Recycling of solid waste. Compacting and incineration of solid waste. Use of biodegradable materials and chemicals. Good soil management to avoid soil erosion. Human Diseases
The term disease denotes any condition or disorder that disrupts the steady state of well being of the body. Health is a state of physical, mental and emotional well being in the internal environment of the body. Some of the causes of diseases are due to entry of pathogens and parasites. Pathogens include bacteria, viruses, protozoa and fungi. Parasites are organisms which live on or in the body of another organisms. Vectors are animals that carry the pathogen from are person to another. Most are ectoparasites that transmit the disease as they feed. Bacterial Diseases
Cholera
Causative agent a bacterium Vibrio cholerae. Transmission - It is spread through water and food contaminated by human faeces containing the bacteria. The bacteria produce a powerful toxin, enterotoxin, that causes inflammation of the wall of the intestine leading to:
Severe diarrhoea that leads to excessive water loss from body. Abdominal pain
Vomiting
Dehydration which may lead to death.
Transmission - It is spread through water and food contaminated by human faeces containing the bacteria. The bacteria produce a powerful toxin, enterotoxin, that causes inflammation of the wall of the intestine leading to:
Severe diarrhoea that leads to excessive water loss from body. Abdominal pain
Vomiting
Dehydration which may lead to death. Prevention and Control
Adequate sanitation such as water purification sewage treatment and proper disposal of human faeces. Public and personal hygiene e.g washing hands before meals and washing fruits and vegetables, boiling drinking water. Vaccination
Carriers should be identified, isolated and treated during outbreaks. Treatment
Use of appropriate antibiotics. Correcting fluid loss by injecting fluids or by administration of oral rehydration solutions. Typhoid
Causative agent. The disease is caused by Salmonella typhi. Transmission is through contaminated water and food. It is also transmitted by certain 'e.g foods, e.g. oysters, mussels and shell fish. Symptoms
Fever
Muscle pains
Headache
Spots on the trunk of the body
Diarrhoea
In severe cases mental confusion may result and death. Prevention
Boil drinking water. Proper sewage treatnient. Proper disposal of faeces, if not flushed use deep pit latrines. Observe personal hygiene e.g. washing hands before meals. Washing fruits and vegetables. Treatment
Use of appropriate antibiotics. Protozoa
Malaria
Malaria is caused by the protozoan plasmodium. The most common species of plasmodium are P. falciparum, P. vivax, P. rnalariae and P. ovale with varying degree of severity. Transmission
Is by female anopheles mosquito as it gets a blood meal. Symptoms
Headache, sweating, shivering, high temperature (40-41 0C) chills and joint pains. The abdomen becomes tender due to destruction of red blood cells by the parasites . Prevention
Destroy breeding grounds for mosquitoes by clearing bushes and draining stagnant water. Kill mosquito larvae by spraying water surfaces with oil. Use insecticides to kill adult mosquitoes
Sleeping under a mosquito net. Take preventive drugs. Treatment
Use appropriate anti-malarial drugs. Amoebic dysentry (Amoebiasis)
Cause
This disease is caused by Entamoeba histolytica.
Take preventive drugs. Treatment
Use appropriate anti-malarial drugs. Amoebic dysentry (Amoebiasis)
Cause
This disease is caused by Entamoeba histolytica. The parasites live in the intestinal tract but may occasionally spread to the liver. Transmission - They are transmitted through contaminated water and food especially salads. Symptoms –
Abdominal pain, nausea and diarrhoea. The parasites cause ulceration of the intestinal tract, which results in diarrhoea. Prevention and control
Proper disposal of human faeces. Boiling water before drinking. Personal hygiene e.g. washing hands before meals. Washing vegetables and steaming particularly salads and fruits before eating. Treatment
Treatment of infected people with appropriate drugs. Parasitic Diseases
Ascaris lumbricoides
Ascaris lumbricoides lives in the intestines of a man or pig, feeding on the digested food of the host. The body of the worm is tapered at both ends. The female is longer than the male. Mode of transmission
The host eats food contaminated with the eggs, the embryo worms hatch out in the intestine. The embryo worms then bore into the blood vessels of the intestine. They are carried in the bloodstream to the heart and then into the lungs. As they travel through the bloodstream, they grow in size. After sometime, the worms are coughed out from the air passages and into the oesophagus. They are then swallowed, eventually finding their way into the intestines where they grow into mature worms. Effects of Ascaris lumbricoides on the host
The parasites feed on the host's digested food. This results in malnutrition especially in children. If the worms are too many, they may block the intestine and interfere with digestion. The worms sometimes wander along the alimentary canal and may pass through the nose or mouth. In this way, they interfere with breathing and may cause serious illness. The larvae may cause severe internal bleeding as they penetrate the wall of the intestine. Adaptive Characteristics
The female lays as many as 25 million eggs. This ensures the continuation of the species. Eggs are covered by a protective cuticle that prevents them from dehydration. The adult worms tolerate low oxygen concentration. Have mouth parts for sucking food and other fluids in the intestines. Has a thick cuticle or pellicle to protect it from digestive enzymes produced by the host. Control and Prevention
Personal hygiene e.g.
Have mouth parts for sucking food and other fluids in the intestines. Has a thick cuticle or pellicle to protect it from digestive enzymes produced by the host. Control and Prevention
Personal hygiene e.g. washing hands before eating. Proper disposal of faeces. Washing of fruits and vegetables. Treatment
Deworm using appropriate drugs ant-helmintics. Schistosoma
Schistosoma or bilharzia worm is a flat worm, parasitic on human beings and fresh water snails. (Biomphalaria and Bulinus.)
The snail act as intermediate host. Mode of Transmission
Schistosomiasis also known as a bilharsiasis is caused by several species of the genus schistosoma. Schistosoma haematobium infects the urinary system mainly the bladder
S. japonicum and S. mansoni both infect the intestines. Schistosoma haemotobium is common in East Africa where irrigation is practised and where slow moving fresh water streams harbour snails. It is spread through contamination of water by faeces and urine from infected persons. The embryo (miracidium) that hatch in water penetrates into snails of the species Biompharahia and Bulinus. Inside the snail's body, the miracidium undergoes development and multiple fission to produce rediae. The rediae are released into the water and develop to form cercariae which infect human through:
Drinking the water
Wading in water;
Bathing in snail-infested water. The cercaria burrows through the skin and enters blood vessel. Effects on the host
Inflammation of tissues where egg lodge. Ulceration where eggs calcify. Egg block small arteries in lungs leading to less aeration of blood. The body turns blue - a condition known as cyanosis. If eggs lodge in heart or brain, lesions formed can lead to death. Bleeding occurs as the worms burrow into blood vessels (faeces or urine has blood). Pain and difficulty in passing out urine. Nausea and vomiting. When eggs lodge in liver ulceration results in liver cirrhosis. Death eventually occurs. Adaptive Characteristics
The female has a thin body and fits into small blood vessels to lay eggs. Eggs are able to burrow out of blood vessel into intestine lumen. Many eggs are laid to ensure the survival of the parasite.
Adaptive Characteristics
The female has a thin body and fits into small blood vessels to lay eggs. Eggs are able to burrow out of blood vessel into intestine lumen. Many eggs are laid to ensure the survival of the parasite. Large numbers of cercariae are released by snail. The miracidia and cercariae larvae have glands that secrete lytic enzymes which soften the tissue to allow for penetration into host. The male has a gynecophoric canal that carries the female to ensure that eggs are fertilised before being shed. Has suckers for attachment. Prevention and Control
Drain all stagnant water
Boil drinking water. Do not wade bare feet in water. Wear long rubber boots and gloves (for those who work in rice fields). Eliminate snails, by spraying with molluscides. Reporting to doctor early when symptoms appear for early treatment. Practical Activities
Ecology is best studied outdoors. Students identify a habitat within or near the school compound, e.g. a flower bed. The quadrat method is used. Observation and recording of the various animals as well as their feeding habits is done. Birds that feed on the plants or arthropods in the area studied are noted through observation of habitat at various times of the day. Food chains are constructed e.g green plants ~ caterpillar ~ lizard and many others involving all organisms in the area. The numbers of animals in 1 m2 is counted directly or estimated e.g small arthropods like black ants. The number of plants is easily counted and recorded and ratio of consumers to producers calculated. It will be noted that in terms of numbers where invertebrates are involved, there are very many consumers of one plant. Several other quadrats are established and studied and averages calculated. Adaptions to Habitat
Hydrophytes
Specimen of hydrophytes e.g water lily is observed. Students should note the poorly developed root systems and broad leaves. Stomata distribution on leaf surface is studied through microscopy or by emersing a leaf in hot water and counting number of bubbles evolved. Mesophytes –
Ordinary plants e.g bean hibiscus and zebrina can be studied. Size of leaves is noted and stomata distribution studied. Xerophytes
Specimen include Euphorbia, cactus and sisal which are easily available. The root system e.g in sisal is noted as shallow but extensive.
Size of leaves is noted and stomata distribution studied. Xerophytes
Specimen include Euphorbia, cactus and sisal which are easily available. The root system e.g in sisal is noted as shallow but extensive. It will be noted that sisal has fleshy leaves and stem while cactus and Euphorbia have fleshy stem but leaves are reduced to small hair-like structures. Comparison of Root nodules from fertile and poor soils
Root nodules –
Are swellings on roots of leguminous plants. Soil fertility determines number of root nodules per plant. Bean plants are best used in this study. One plot can be manured while the other is not. Similar seeds are planted in the two plots. The plants are uprooted when fully mature (vegetatively) i.e any time after flowering and before drying. The number of nodules per plant is counted. An average for each plot is calculated. It is noted that the beans from fertile soil have more and large nodules than those grown in poor soils. Estimation of Population using Sampling Methods
The number of organisms both producers and the various consumers is recorded in each area studied e.g. using a quadrat. The total area of the habitat studied is measured. The average number of organisms per quadrat (1 m2) is calculated after establishing as many quadrats as are necessary to cover the area adequately. Total population of organisms is calculated from the area. Abiotic environment is studied within the area sampled. Air temperature soil surface temperature are taken and recorded. This is best done at different times of day, i.e., morning afternoon and evening. Any variations are noted. pH of the soil is measured using pH distilled water to make a solution. Litmus papers can be used to indicate if soil is acidic or alkaline, but pH paper or meter gives more precise pH values. Humidity is measured using anhydrous blue cobalt chloride paper which gives a mere indication of level of humidity. A windsock is used to give an indication of direction of wind. As all the abiotic factors are recorded observations are made to find the relationships between behaviour of organism and the environmental factors for example:
The temperature affects the behaviour of animals. The direction of wind will affect growth of plants. The level of humidity determines the type, number and distribution of organisms in an area. REPRODUCTION IN PLANTS AND ANIMALS
Introduction
The process by which mature individuals produce offspring is called reproduction.
The direction of wind will affect growth of plants. The level of humidity determines the type, number and distribution of organisms in an area. REPRODUCTION IN PLANTS AND ANIMALS
Introduction
The process by which mature individuals produce offspring is called reproduction. Reproduction is a characteristic of all living organisms and prevents extinction of a species. There are two types of reproduction: sexual and asexual reproduction. Sexual reproduction involves the fusion of male and female gametes to form a zygote. Asexual reproduction does not involve gametes. Cell Division
Cell division starts with division of nucleus. In the nucleus are a number of thread-like structures called chromosomes, which occur in pairs known as homologous chromosomes. Each chromosome contains-genes that determine the characteristics of an organism. The cells in each organism contains a specific number of chromosomes. There are two types of cell division:
Mitosis –
This takes place in all body cells of an organism to bring about increase in number of cells, resulting in growth and repair. The number of chromosomes in daughter cells remain the same as that in the mother cell. Meiosis –
This type of cell division takes place in reproductive organs (gonads) to produce gametes. The number of chromosomes in the gamete is half that in the mother cell. Mitosis
Mitosis is divided into four main stages. Prophase, Metaphase, Anaphase and Telophase. These stages of cell division occur in a smooth and continuous pattern. Interphase
The term interphase is used to describe the state of the nucleus when the cell is just about to divide. During this time the following take place:
Replication of genetic material so that daughter cells will have the same number of chromosomes as the parent cell. Division of cell organelles such as mitochondria, ribosomes and centrioles. Energy for cell division is synthesised and stored in form of Adenosine Triphosphate (ATP) to drive the cell through the entire process. During. interphase, the following observations can be made:
Chromosomes are seen as long, thin, coiled thread-like structures. Nuclear membrane and nucleolus are intact. Prophase
The chromosomes shorten and thicken. Each chromosome is seen to consist of a pair of chromatids joined at a point called centromere. Centrioles (in animal cells) separate and move to opposite poles of the cell. The centre of the nucleus is referred to as the equator.