Transpiration: The Process and Significance
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Objectives of Teaching Classification 1: Developing a Deeper Understanding of Living Organisms20/11/2023 Objectives of Teaching Classification 1
This information aligns with the Kenyan 8-4-4 education system, which is currently being replaced by the Competency-Based Curriculum (CBC) system. Classification 1 is a topic covered in Form 1 and is commonly examined by the Kenya National Examinations Council (KNEC) during the Kenya Certificate of Secondary Education (KCSE) examinations. The primary purpose of sharing this piece is to provide teachers and learners with valuable insights on what to focus on when studying this topic.
Objectives of Teaching Classification
Teaching classification plays a crucial role in helping learners develop a deeper understanding of the living world around them. By the end of this topic, learners should be able to achieve the following objectives:
Classification 1, Topics, Sub-Topics and Other Contents
Taxonomic Groups
The groups are Taxa (singular Taxon).
These groups, known as taxonomic levels, help in organizing and categorizing the vast diversity of living organisms. The taxonomic groups, in ascending order, are as follows:
Introduction to Classification I. Biology Form 1 Notes
Using a Magnifying Lens
Necessity/need for Classification
Understanding Eczema and Its Impact on Skin Health
Eczema, also known as atopic dermatitis, is a common skin condition characterized by dry, itchy, and inflamed patches of skin. It is not contagious and can vary in severity from mild to severe. Eczema can affect people of all ages, including infants, children, and adults.
Causes of Eczema:
Symptoms of Eczema:
Types of Eczema:
There are several types of eczema, including:
Treatment of Eczema:
While there is no cure for eczema, there are various treatment options available to manage symptoms and reduce flare-ups. These may include:
Learn more:
Why do animals become resistant to drugs?
Causes and Implications of Drug Resistance in Animal Populations
Introduction:
Drug resistance, or specifically antibiotic resistance, is a significant global concern that affects not only humans but also animals. This resistance occurs when microorganisms, such as bacteria and parasites, develop the ability to survive exposure to drugs that were once effective against them. Understanding the reasons behind the development of drug resistance in animals is crucial for addressing this growing problem.
Body:
Conclusion:
The emergence and spread of drug resistance in animals pose a significant threat to public health, animal health, and food production. Understanding the causes of drug resistance is crucial for implementing effective strategies to mitigate its impact. Addressing the overuse and misuse of drugs, promoting responsible use in agricultural and veterinary practices, facilitating the development of new drugs, and implementing infection control measures are essential steps towards combating drug resistance and preserving the efficacy of available treatment options. A comprehensive and collaborative approach is necessary to tackle this global challenge and ensure the continued effectiveness of drugs in the treatment of animal and human diseases.
CLASSIFICATION I:Binomial Nomenclature
Kingdoms
Living organisms are classified into five kingdoms namely;
Kingdom Fungi
Kingdom Monera (Prokaryota)
Kingdom Protoctista
Kingdom Plantae
Kingdom Animalia
External Features of Organisms
In plants we should look for:-
(I) FOSSIL RECORDS
Structural differences between apes and humans(ii) Comparative Anatomy
Examples of adaptive radiation I.Homologous structures
Beaks in birds have a common embryonic origin and basic structure. Depending on the type of food and mode of feeding this basic structure is modified in length, shape and size e.g. -Short stout beaks are common in seed eaters e.g. weaver birds. -Long slender beaks for nectar feeders e.g. sunbirds. -Strong hooked beaks for carnivorous birds e.g. eagles (c)Foot structure in birds They are modified for various functions and habitats although they have a common embryonic origin e.g.
This is where different structures are modified to perform similar functions. E.g. (i)Analogous structures They are those structures that have different embryonic origin but have evolved to perform similar functions due to the exploitation of the same kind of environment. Examples of analogous structures a.Wings The wings of birds and those of insects have different embryonic origin but both are adapted for flight. b.(ii) Eye structure The eye structures of humans and that of octopus are similar but their embryonic origin is different. III Vestigial structures They are those structures that have in the course of time ceased to be functional and therefore have become reduced in size or rudimentary. c.Examples of vestigial structures Appendix in man has no digestive function while in herbivores e.g. rat, its well developed and functions as the cellulose-digesting part of the alimentary canal. The python and the whale have no externally visible hind limbs but their original presence is evidenced by the existence of a rudimentary pelvic girdle. The kiwi (flightless bird) of New Zealand has reduced wings beneath the body plumage. A vestigial tail is present in humans in the form of a much reduced coccyx. The nictitating membrane in the eye of the mammals is now reduced and functionless; but in birds and fish it can move over the eye and act as the 3rd eyelid. (iii) Comparative embryology (j)The embryos of different vertebrate groups (fish, birds, amphibians, reptiles and mammals are morphologically similar during the early stages of development. This relationship is as a result of their common ancestry. The closer the resemblance between the early stage embryos, the closer is their evolutionary relationship. This theory is called recapitulation theory. It can also be atated as “ontogeny recapiturates phylogeny” (iv) Geographical distribution of organisms The theory of “continental drift” supposes that at one time the present continents formed one large single land mass which later broke up and the parts drifted away from each other. Before drifting occurred there had been migration of animals from the centre of the land mass mainly fro Asia to Australia. After the drift, animals with a common ancestry became isolated and evolved into different species. a.Examples Amazon forest in South America is inhabited with monkeys with long tails while in African forests there are the short-tailed monkeys. The panthers and the jaguars in the forests represent the cat family while in Africa we have the leopards and cheetahs and in Asia there are the tigers. The llamas of the Amazon forest and modern camels of Africa and Asia are thought to have had a common ancestry in North America. It’s believed that from their common points of origin, they migrated into different continents thus became isolated and evolved into different species. The process of initial migration and subsequent isolation by physical barriers such as oceans, dry deserts and mountains seems to have given rise to a wide variety of animal and plant types. (v)Cell biology The cells of all higher organisms show basic similarities in their structure and functions. Thus all these cells contain cell membranes and organelles such as ribosome, Golgi bodies, mitochondria etc. (k)They also have some biological chemicals in common e.g. ATP and DNA. This strongly indicates that all cell types have a common ancestral origin. (l)Also plant cells contain cellulose cell wall, cell sap, chloroplast etc. all these features are absent in animal cells. (m)Among animals blood pigments are of universal occurrence. These include haemoglobin (vertebrates and invertebrates), haemocyanin (moluscs and crustaceans) and chlorocruorin (annelids). (vi)Comparative serology (n)Experiments with serum (serological tests) are used to show phylogenetic relationships e.g. (o)-If human serum is injected into a rabbit, the proteins in the serum act as antigens. The rabbit produces antibodies against the human proteins. When blood with antibodies is drawn from the rabbit and mixed with serum from different animals, an immunological reaction occurs forming a precipitate. The amount of precipitate formed varies from one animal to the other. The greater the amount the closer the phylogenetical relationship between the animal and the human being. Mechanism of evolution Lamarck’s theory (Theory of use and disuse) (p)This theory was proposed by Jean Baptiste de Lamarck (1815). He proposed that when the environment demanded the need for a particular structure in an organism, the organism develop it in response to the demand. This led to the natural use and disuse of structures producing changes in the individual during its life time. He further proposed that these changes or structures that were acquired during the life time of an individual were then transmitted to their offspring and subsequent generations resulting in the emergence of new forms or new species. a.Examples
NB This theory was rejected because phenotypically acquired characteristics which do not affect the genotype of an individual cannot be inherited. Darwin’s theory of Natural selection This theory was proposed by Charles Darwin (1859). a.Main features of the theory He observed that variations arose by chance and from within the individual. Through sexual reproduction the characteristics are transmitted to successive offspring. Some of the variations confer an advantage to the individual while others are disadvantageous. He proposed that in nature there exist a phenomenon known as “Natural selection” which “selects” those individuals best suited to an environment. He observed that the number of offspring by far outnumber the parental generation but due to eliminating factors such as predation, diseases, competition for food, breeding conditions etc only a few survive to adulthood and are able to reproduce. He explained that in nature there exists a “struggle for existence” and those best suited for an environment survive. He called this “The survival of the fittest”. He proposed that “Natural selection” is a chance occurrence. Neither the environment nor the individual controls the direction of change. Those individuals that are selected for reproduction thus transmit the variations to their offspring. The gradual accumulation of small variations from generation to generation over a long period of time leads to the emergence of new forms of species. Natural selection in action Strains or varieties could offer evidence of evolution in progress e.g. i Peppered moth (Biston betularia) This moth occurs in Britain. They occur in two forms i.e. speckled white form and black melanic form. Before the industrial revolution, the speckled white form was well camouflaged against tree trunks with similar pattern and colouration. But around 1848 during industrial revolution the environment was darkened by soot. Due to this change the black melanic form blended well against the bark of trees which had been darkened by soot and smoke. These darker forms were better protected in the industrial area against predation from birds than the lighter forms. In the smoke and soot polluted areas there is greater frequency of black melanic form while in the soot free areas the speckled white form predominates. Thus the agent of natural selection was selective predation on the unprotected forms. e.g. ii Sickle cell trait It’s known that there is a high frequency of this mutant gene in places where malaria incidence is high. This is because those who are heterozygous HbAHbS have immunity to malaria a situation called heterozygous advantage. e.g. iii Resistance to drugs, pesticides and antibiotics Some pathogens and pests usually survive and reproduce even when they are exposed to the antibiotics and pesticides repeatedly. These instances show that within the population some individuals posses the gene for resistance or acquire it through mutation hence survives the chemical. Those that survive transmit this characteristic to their offspring thus establishing a new population of resistant forms. -Mosquitoes posses a gene that makes them synthesise an enzyme against DDT. -The control of plasmodium has been made difficult due to the ability of the plasmodium to rapidly change its coat surface antigens. This makes the plasmodia resist the drug meant to kill them. Chemical evolution
Key Points
Evolution is the process that attempts to explain the origin, diversity, and unity of life. It involves the gradual change of living organisms from simple life forms to more complex forms over a long period of time. There are different theories that try to explain the origin of life.
One theory is the concept of special creation, which is a belief held by major religions and folklore. It states that the whole universe and everything within it were created by a supreme being, such as God. According to this theory, life forms were created in a perfect form and have remained unchanged over time. This belief is based on faith and is not scientifically testable or disputable. Another theory is chemical evolution, which suggests that life probably began through the chemical reactions of light bringing together elements to form simple molecules such as water, ammonia, and methane. It is theorized that millions of years ago, simple molecules in the universe combined to form different compounds, which eventually led to the formation of complex molecules like DNA. The replication of these molecules resulted in the formation of simple life forms like viruses and bacteria. This period of the combination of chemicals to form the first living organisms is called the period of chemical evolution. The theory of chemical evolution holds that life came into existence through combinations of chemicals. The initial life forms were simple and have changed over the years to form the complex organisms we see today. This is known as the principle of organic evolution. There is scientific evidence in the form of experiments, artifacts, and fossils that support this theory. It is also theorized that the universe came into existence approximately 15 billion years ago, the solar system formed about 6 billion years ago, and the Earth formed 4 billion years ago. Since then, the Earth has undergone cooling and structural changes, providing an environment for the development of living organisms. Evidence for organic evolution includes fossil records, which show the existence of organisms that have changed over time. Additionally, the theory of natural selection proposed by Charles Darwin explains how variations within a species can lead to the emergence of new forms. Natural selection occurs when individuals with traits that are best suited for their environment have a higher chance of survival and reproduction, passing on these advantageous traits to their offspring. In summary, evolution is the process that explains the origin, diversity, and unity of life. It involves gradual changes in living organisms over time. Theories such as special creation and chemical evolution attempt to explain the origin of life. The theory of organic evolution suggests that life forms have changed over time, supported by scientific evidence such as fossils. Natural selection plays a role in the emergence of new forms, as individuals with advantageous traits are more likely to survive and reproduce. BIOLOGY NOTES FORM 4 IN PDF
Transport in Plants and Animals
Transport in plants
Internal structure of roots and root hairs
The main functions of roots are;
Internal structure of a root hair cell
The main functions of the stem are;
Collenchyma
The Stem
Absorption of Water and Mineral Salts Absorption of Water
Transpiration
Structure and function of Xylem
Tracheids
Forces involved in Transportation of Water and Mineral Salts
Transpiration pull
As water vaporises from spongy mesophyll cells into sub-stomatal air spaces, the cell sap of mesophyll cells develop a higher osmotic pressure than adjacent cells. Water is then drawn into mesophyll cells by osmosis from adjacent cells and finally from xylem vessels. A force is created in the leaves which pulls water from xylem vessels in the stem and root. This force is called transpiration pull. Cohesion and Adhesion: The attraction between water molecules is called cohesion. The attraction between water molecules and the walls of xylem vessels is called adhesion. The forces of cohesion and adhesion maintain a continuous flow of water in the xylem from the root to the leaves. Capillarity: This is the ability of water to rise in fine capillary tubes due to surface tension. Xylem vessels are narrow, so water moves through them by capillarity. Root Pressure: If the stem of a plant is cut above the ground level, it is observed that cell sap continues to come out of the cut surface. This shows that there is a force in the roots that pushes water up to the stem. This force is known as root pressure.
Importance of Transpiration
Transpiration leads to excessive loss of water if unchecked. Some beneficial effects are:
The factors that affect transpiration are grouped into two. i.e. environmental and structural. Environmental factors Temperature High temperature increases the internal temperature of the leaf. Which in turn increases kinetic energy of water molecules which increases evaporation. High temperatures dry the air around the leaf surface maintaining a high concentration gradient. More water vapour is therefore lost from the leaf to the air.
Humidity
The higher the humidity of the air around the leaf, the lower the rate of transpiration. The humidity difference between the inside of the leaf and the outside is called the saturation deficit. In dry atmosphere, the saturation deficit is high. At such times, transpiration rate is high. Wind Wind carries away water vapour as fast as it diffuses out of the leaves. This prevents the air around the leaves from becoming saturated with vapour. On a windy day, the rate of transpiration is high. Light Intensity When light intensity is high; more stomata open hence high rate of transpiration. Atmospheric Pressure The lower the atmospheric pressure the higher the kinetic energy of water molecules hence more evaporation. Most of the plants at higher altitudes where atmospheric pressure is very low have adaptations to prevent excessive water-loss. Availability of Water The more water there is in the soil, the more is absorbed by the plant and hence a lot of water is lost by transpiration.
Structural Factors
Cuticle Plants growing in arid or semi-arid areas have leaves covered with a thick waxy cuticle. Stomata The more the stomata, the higher the rate of transpiration. Xerophytes have few stomata which reduce water-loss. Some have sunken stomata which reduces the rate of transpiration as the water vapour accumulates in the pits. Others have stomata on the lower leaf surface hence reducing the rate of water-loss. Some plants have reversed stomatal rhythm whereby stomata close during the day and open at night. This helps to reduce water-loss. Leaf size and shape Plants in wet areas have large surface area for transpiration. Xerophytes have small narrow leaves to reduce water-loss. The photometer can be used to determine transpiration in different environmental conditions. Translocation of organic compounds Translocation of soluble organic products of photosynthesis within a plant is called translocation. It occurs in phloem in sieve tubes. Substances translocated include glucose, amino acids, and vitamins. These are translocated to the growing regions like stem, root apex, storage organs e.g. corms, bulbs and secretory organs such as nectar glands. Phloem
Phloem is made up of;
TRANSPORT IN PLANTS.
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TABLE OF CONTENTS
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Protection
Maternal blood and foetal blood do not mix. This ensures that the pathogens and toxins from maternal blood do not reach the foetus. The placenta allows maternal antibodies to pass into the foetus, providing the foetus with immunity. |
January 2024
November 2023
October 2023
September 2023
March 2023
January 2023
October 2022
September 2021
June 2021
May 2021
All
CELL PHYSIOLOGY
Classification 1
CLASSIFICATION II
ECOLOGY
EVOLUTION
EXCRETION AND HOMEOSTASIS
FORM 1
FORM 2
FORM 3
FORM 4
Gaseous Exchange In Animals
GASEOUS EXCHANGE IN PLANTS AND ANIMALS
GROWTH & DEVELOPMENT
HUMAN DISEASES
INTRODUCTION TO BIOLOGY
Lipids
MEASUREMENT OF GROWTH
NUTRITION IN ANIMALS
NUTRITION IN PLANTS AND ANIMALS
PDF NOTES
PRACTICAL ACTIVITIES
REPRODUCTION IN PLANTS AND ANIMALS
RESPIRATION
THE CELL
Transport In Animals
TRANSPORT IN PLANTS AND ANIMALS
Primary Resources
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