Grade 11 Biology Notes
General Textbook Information
This document is a Biology student textbook for Grade 11, published in August 2023 by the Federal Democratic Republic of Ethiopia, Ministry of Education.
ISBN: 978-99990-0-010-9
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Unit One: Biology and Technology
1.1 Learning from Nature
Nature: the physical, natural, and material world of life that exists without human intervention, including landscapes, ecosystems, weather patterns, and diverse organisms.
Organisms possess well-adapted structures for survival in their environments demonstrating evolutionary adaptation.
Nature provides structures and forms that can be developed into functional technological systems, offering inspiration for innovative designs.
Scientists and engineers imitate physical structures, shapes, materials, and functional mechanisms from nature to create effective technologies.
Understanding biological materials enhances the ability to develop technologies that mimic or utilize natural processes.
Imitation involves sketching biological structures, designing functional mechanisms, and tuning into efficient technologies inspired by nature.
1.2 Biology and Technology
Biology: the study of life, including the structures, functions, growth, origins, evolution, and distribution of living organisms and their interactions.
Technology: the application of scientific knowledge, skills, methods, and processes for the production of devices and tools to solve problems and enhance scientific investigations.
Biotechnology: the integration of natural and engineering sciences to apply organisms, cells, parts, and molecular analogues for products and services (e.g., using yeasts to produce bread and beer, and employing microorganisms for antibiotics).
1.2.1 The Benefits of Biology to Technology
Biology provides materials and insights for imitation, design, adaptation, and development of modern technologies.
Nature's diversity stimulates new technologies by offering a wide array of solutions and adaptations.
Scientists and engineers imitate nature for innovation and problem-solving, creating technologies that are both efficient and sustainable.
Examples:
Medicinal plants leading to the development of medicines that treat diseases and improve human health.
Gene engineering and biosynthetic materials for curing genetic conditions and tissue repair.
Building design from termite mound architecture, providing natural ventilation and temperature regulation.
Bullet train design imitating the beak of a kingfisher to reduce noise and improve aerodynamic efficiency.
1.2.2 Uses of Technology in Biology
Technology provides tools to solve human problems and investigate biological questions, enhancing research capabilities and understanding.
Biological studies using technological tools:
Biochemical studies: investigating carbohydrates, proteins, lipids, and nucleic acids information through advanced techniques like chromatography and spectroscopy.
Biomedical studies: Chemistry components of medicinal plants using methods like mass spectrometry and nuclear magnetic resonance (NMR).
Biophysical studies: using physical devices such as electron microscopes and X-ray diffraction to study biological structures.
Environmental studies: interactions of humans with the environment using remote sensing and GIS technologies.
Bioinformatics: using computer technology to collect, store, analyze, and disseminate biological data, including genomics and proteomics information.
Biogeographical information: species distribution along with geographic ecosystems through geological periods using GPS tracking and ecological modeling.
1.3 Impacts of Biology and Technology on Society and the Natural World
Biology and technology can have positive and negative effects on society and the natural world, creating complex challenges.
1.3.1 Impacts of Biology on the Society and the Natural World
Positive impacts:
Ensuring food security through increased productivity and sustainable agricultural practices.
Improved health and longevity via medicine and disease treatments.
Better energy and clean water supplies through biological innovations.
Increased industrial production via microbial action and biotechnological applications.
Negative impacts:
Biological weapon production and use, destroying the natural world.
Predetermined selection of child sex chromosomes, leading to unequal gender distribution that can affect the society and the natural world
1.3.2 Impacts of Technology on the Society and the Natural World
Technology has solved societal problems but also resulted in environmental destruction and resource depletion.
Negative impacts:
Pollution from industrial emissions and effluents, leading to air and water contamination.
Toxicity and biohazards from biochemical agents, pesticides, and fertilizers, harming ecosystems and human health.
1.4 Ethical Issues in Biology
Ethical issues arise concerning the appropriateness of using biological discoveries for human health and well-being.
These issues relate to biotechnology, medicine, and the environment requiring careful consideration and regulation.
1.4.1 Ethical Treatment of Plants and Animals During Biological Studies
Ethical treatment involves considering the well-being and rights of plants and animals during experiments and tests to ensure responsible conduct.
1.4.1.1. Ethical Treatment of Plants
Plants are primary producers critical to ecosystems maintaining ecological balance and supporting food chains.
Severe impacts on plant species can lead to their disappearance, disrupting ecosystem functions.
Unethical treatments:
Testing seeds/berries through destructive rays, affecting germination and plant health.
Cutting tree terminals for experiments disrupts their growth patterns without proper justification.
Consumption of all seeds and fruits without conservation, reducing natural regeneration.
Unplanned deforestation.
Burning forests for farmlands, destroying habitats and ecosystems.
Restructuring tree shapes for aesthetic appeal, altering their natural growth.
1.4.1.2. Ethical Treatment of Animals in Experiments
Animals are sentient creatures capable of feeling pain and stress, requiring humane treatment in research.
Unethical treatments include experiments causing injury or pain, requiring careful ethical oversight.
The Three Rs Principles: Reduction, Refinement, and Replacement.
Reduction: Minimizing the number of animals used to obtain necessary data.
Refinement: Reducing suffering through less invasive techniques and better care.
Replacement: Substituting animals with alternative techniques like cell cultures, computer models, or in vitro studies.
Unit Two: Animals
2.1 Characteristics of Animals
Animals are eukaryotic, multicellular, heterotrophic, and sensitive to stimuli, displaying diverse adaptations.
They reproduce, protect themselves, move, respire, excrete, grow, and have different body symmetries, showcasing biological diversity.
Animals are categorized into invertebrates (no backbone) and vertebrates (with backbone), reflecting fundamental differences in structure.
2.2 Invertebrates and Vertebrates
2.2.1 Invertebrate Animals
Invertebrates do not have a backbone, representing a vast array of species.
They are a diverse group found in various environments, including terrestrial, freshwater, and marine habitats.
They lack a rigid internal skeletal system; some have an exoskeleton like insects and crustaceans which provides protection and support.
Examples: earthworms, insects, spiders, snails, jellyfish, lobsters, crabs, and sea stars, showcasing the breadth of invertebrate diversity.
2.2.2 Vertebrate Animals
Vertebrates have a well-defined internal skeleton with cartilage and a backbone, providing structural support.
They have complex organ systems like circulatory, respiratory, nervous, and excretory systems, which facilitate advanced physiological functions.
Examples: mammals, birds, fish, reptiles, and amphibians, illustrating the major groups of vertebrates.
2.3 Reproduction in Animals
Reproduction ensures the continuity of species, maintaining genetic diversity.
Two types: asexual and sexual reproduction, adapting to different environmental conditions.
2.3.1 Asexual Reproduction in Animals
Involves a single individual, and does not require the fusion of gametes; more common among invertebrates.
Forms include budding, fragmentation, and parthenogenesis (unfertilized eggs develop into new offspring), allowing rapid population growth under favorable conditions.
2.3.2 Sexual Reproduction in Animals
Involves two parents and the fusion of gametes (sperm and egg), enhancing genetic variation.
Offspring have genetic material from both parents, contributing to evolutionary adaptation.
Involves the production of haploid gametes (n).
Fertilization can be external or internal, occurring in aquatic or terrestrial environments.
Fertilization produces a diploid zygote (2n) which develops into an embryo, initiating new life.
Embryonic development involves cleavage, blastula formation, gastrulation, and organogenesis.
2.3.3 Reproduction in Insects (Complete and Incomplete Metamorphosis)
Insects undergo sexual reproduction, some undergo parthenogenesis, allowing varied reproductive strategies.
Metamorphosis involves major changes in body structure, adapting insects to different life stages.
Two types of metamorphosis: Complete (egg, larva, pupa, adult) and Incomplete (egg, nymph, adult).
2.3.4 Reproduction in Frog
Frogs undergo sexual reproduction with male and female reproductive structures, requiring aquatic environments.
They have external fertilization; some species have internal fertilization, depending on their habitat.
Eggs are covered in a jelly-like substance, providing protection and hydration.
They go through a larval stage called a tadpole, undergoing metamorphosis to become adult frogs.
2.3.5 Reproduction in Crocodiles
Crocodiles reproduce sexually, involving both male and female parents using internal fertilization, an adaptation to terrestrial life.
They lay eggs and bury them in sand or vegetation, protecting the eggs from predators and environmental conditions.
Eggs are hard and leathery to protect young.
2.3.6 Reproduction in Birds
Birds reproduce sexually with internal fertilization, optimizing reproductive success.
Male birds do not have external genital organs and females have a single ovary, reflecting avian adaptation.
During mating, the male brings its sperm to the female cloaca to fertilize the egg.
Birds lay hard-shelled eggs with a fluid-filled amnion, providing a protective environment for embryonic development.
Most birds are monogamous but there are also polygamous species, showing diverse mating systems.
Incubation keeps eggs warm, and hatching involves breaking the eggshell.
Parental care includes building nests for their offspring.
2.3.7 Reproduction in Rat
Rats reproduce sexually, with rapid reproduction rates.
Fertilization occurs inside the female, and gestation periods vary by species.
Blastulas implant in the uterine horns, developing into embryonic and extra-embryonic tissue to support rapid embryonic growth.
Parental care involves building nests and nursing pups.
2.4 The Economic Importance of Animals (Insects)
Insects have significant economic importance in agriculture, food, industry, health, and medicine.
2.4.1 Beneficial Aspects of Insects
Agriculture: Insect pollinators are essential for crop production which increase the output of crops that depend on insect pollination.
Pest regulation: Insect predators and parasitoids control pests, playing an important role in limiting potential pest populations. Stagmomantis insects feeds on grasshoppers and caterpillars, ladybird beetle feeds on aphids.
Food: Insects are a valuable protein source for global food demand, widely recognized as a sustainable animal protein. Examples are crickets, grasshoppers, beetle and moth larvae and termites
Industry:
Production of honey and beeswax by honeybees, contributing to food and cosmetic industries.
Production of silk from silkworms(Bombyx mori and other silk worms), used in textiles and manufacturing.
Production of shellac from Lac insects (Laccifer lacca) used as varnishes and polishes.
Production of cochineal pigment from scale insects (Dacylopius coccus) which gives color in textile and food and beverage industries.
Production of tannic acid from tree galls in the family Cynipidae for tanning industries
Health and medicine:
Honey: treat burns and wounds, providing antibacterial properties and promoting healing.
Bee and ant venom: treat joint pain reducing inflammation and alleviating pain.
Beetles (Cantharidan): effective in treating severe viral infections and cancerous tumors exhibiting therapeutic benefits.
Grasshoppers ground up: pain reliever, especially for migraines offering traditional medicinal uses.
2.4.2 Harmful Aspects of Insects
Insects can be pests of plants, fruits, and grains, causing economic damage.
Locusts can destroy crops as vectors for disease transmission.
Anopheles mosquitoes transfer malarial parasites, leading to public health crises.
Culex mosquitoes spread filariasis, causing chronic health issues.
Tsetse flies spread African sleeping sickness, affecting human populations and livestock.
Houseflies spread food and water-borne diseases, posing hygiene challenges.
2.5 Animal Behavior
Animal behavior means all the ways in which, animals interact with other organisms and the physical environment: movements, interactions, and learning.
2.5.1 Types of Animal Behavior
Two types of animal behavior: innate (instinctive, reflexive, orientation) and learned (habituation, classical conditioning, operant conditioning).
Innate or Inherent behavior
Innate behavior: inborn that are determined by genes and independent of experience, specific to a species. These are instinctive, reflexive, and orientative.
Instinctive: web building of spider, swimming of dolphin
Reflexive: removal of your hand after touching sharp object
Orientative behaviors:
Taxis (directed), movement of cockroachs from light sources
Kinesis (Undirected), the movement of woodlice in relation to temperature around
Learned or Acquired behavior
Not inherited and acquired during an individual’s lifetime; allowing the organism to adapt to changes in the environment.
Habituation: a decrease in response to a repeated stimulus
Classical conditioning, Pavlov experiment.
Operant conditioning， BF Skinner experiment.
Insight learning.
Sensitization. Progressive amplification of a response.
2.5.2 Patterns of Behavior
Different behavioral patterns exhibited by animals include behavioral cycles, reproductive behavior, social behavior, competition, territory, and communication.
Behavioral cycles: rhythms for example sleep cycles, circadian rhythms.
Reproductive behavior: courtship dance.
Social behavior: insects in colonies of termites exhibit well developed social patterns.
Competition: territoriality.
Communication: visual and sound such as bird sing and frogs croak.
2.6 Homeostasis in Animals
Homeostasis is the self-regulatory process by which animals maintain stable internal conditions regardless of external conditions.
2.6.1 Thermoregulation
Thermoregulation is the process of maintaining a constant internal body temperature, optimizing physiological functions.
Animals grouped into:
Poikilothermic (Cold blooded): Body temperature varies with the environmental temperature seeking warm places.
Homeothermic/endothermic (Warm blooded): Body temperature is constant even when the environment changes. Morphological, physiological and behavioral temperature regulation are used to maintain a stable internal environment.
Birds and mammals can retain heat or lose heat because of vasoconstriction, vasodilation,Sweating, or shivering, facilitating heat exchange.
The heat maintenance or loss occurs in the area called hypothalamus, part of the brain.
Radiation, evaporation, convection and conduction help by maintaining temperature and its heat exchange between animals and their environment.
2.6.2 Osmoregulation
Osmoregulation is the process that regulates the osmotic pressure of fluids and electrolytic balance in organisms to maintain homeostasis.
Organisms are either osmoconformers or osmoregulators, adapting to different osmotic environments.
Kidneys play a central role, controlled by osmoreceptors in the hypothalamus and Antidiuretic hormone (ADH) secreted from pituitary gland to maintain water level and releases a large amount of hypotonic urine when the water level in the body is high.
2.6.3 Blood Sugar Regulation
Glucose concentrations in the blood are regulated through the hormones insulin and glucagon, maintaining energy balance.
Insulin increases amount of glucuose for fuel, high blood glucose stimulates insulin, which promotes glucose transformation to store as glycogen; glucagon increases glucose for the need, low blood glucose stimulates glucagon, which promotes glycogen release
2.6.4 Control of Homeostasis
Homeostasis mechanism involves sensors(receptors), control centers(the brain), stimulus, and effectors where animals respond to their environments. This is done with negative feedback and also reverse positive feedback by having three basic components: Receptor) sensor.) Effector., and (Control Center.
2.7 Renowned Zoologists in Ethiopia
Zoology study the evolution, anatomy, physiology, behavior, habitats and health of animals.
Researchers conduct study on different animals and create a great contribution to the development of zoological science not only on the development of zoological science but also for economic development. Such researchers are patriots for their country.
Unit Three: Enzymes
3.1 What are Enzymes?
Enzymes are proteins that act as biological catalysts by lowering activation energy for the conversion fo products and their substrates.
The process of chemical and physical changes, including the breakdown (catabolism) and synthesis (anabolism) of molecules called metabolism, require enzymes in metabolic cells to catalyze many biochemical reaction types at a rates fast enough to sustain life.