NEET Biology: The Living World

• Biology is the science of life, exploring the structure, function, growth, origin, evolution, and distribution of living organisms.
• NEET UG (National Eligibility cum Entrance Test - Undergraduate) is a national-level entrance exam in India for students who wish to study undergraduate medical courses (MBBS, BDS, AYUSH) in government and private medical colleges.
• The NEET-UG biology section is divided into two parts: Botany and Zoology.

Living World

• Living organisms possess characteristics like growth, reproduction, metabolism, consciousness, cellular organization, and the ability to respond to stimuli.
• Taxonomy is the science of classifying organisms into hierarchical groups based on similarities and evolutionary relationships.
• A species is a group of similar individuals that can interbreed and produce fertile offspring.
• The five kingdom classification system (Monera, Protista, Fungi, Plantae, Animalia) was proposed by R.H. Whittaker, based on cell structure, body organization, mode of nutrition, reproduction, and phylogenetic relationships.
• A virus is a non-cellular organism consisting of a nucleic acid core (DNA or RNA) surrounded by a protein coat (capsid); it replicates only inside a host cell.

Biological Classification

• Monera includes prokaryotic organisms (bacteria, archaea, cyanobacteria). Bacteria can be autotrophic or heterotrophic.
• Protista includes eukaryotic, unicellular organisms.
• Fungi are eukaryotic, heterotrophic organisms, many of which are saprophytes (decomposers).
• Plantae includes all eukaryotic, chlorophyll-containing organisms (plants).
• Animalia includes multicellular, eukaryotic organisms that are heterotrophic.

Plant Kingdom

• Algae are chlorophyll-bearing, simple, thalloid, autotrophic, and aquatic organisms.
• Bryophytes are plants that live in moist habitats and lack true roots, stems, and leaves.
• Pteridophytes are vascular plants with true roots, stems, and leaves, but they reproduce through spores.
• Gymnosperms are plants with naked seeds (seeds not enclosed within an ovary).
• Angiosperms are flowering plants with seeds enclosed within fruits. They are divided into two groups: dicots and monocots.
• Alternation of generations is the life cycle pattern in plants, involving both haploid (gametophyte) and diploid (sporophyte) phases.

Animal Kingdom

• The animal kingdom is characterized by multicellular, heterotrophic eukaryotes.
• Important phyla include Porifera (sponges), Cnidaria (jellyfish, corals), Platyhelminthes (flatworms), Aschelminthes (roundworms), Annelida (segmented worms), Arthropoda (insects, spiders, crustaceans), Mollusca (snails, clams, squids), Echinodermata (starfish, sea urchins), and Chordata (animals with a notochord).
• Chordates possess a notochord, a dorsal hollow nerve cord, pharyngeal gill slits, and a post-anal tail.
• Vertebrates are chordates with a vertebral column.

Morphology of Flowering Plants

• The root system anchors the plant and absorbs water and minerals.
• The stem supports the leaves, flowers, and fruits and conducts water and nutrients.
• The leaf is the primary photosynthetic organ of the plant.
• The flower is the reproductive structure of angiosperms.
• The fruit develops from the ovary after fertilization.
• Different types of plant tissues include meristematic tissues (responsible for growth) and permanent tissues (parenchyma, collenchyma, sclerenchyma, xylem, phloem).

Anatomy of Flowering Plants

• Plant anatomy deals with the internal structure of plants.
• Tissues are groups of cells having a common origin and performing a specific function.
• Vascular bundles contain xylem and phloem, responsible for the transport of water and nutrients.
• The epidermis is the outermost protective layer of the plant.
• The cortex is the region between the epidermis and the vascular bundles.
• The pith is the central core of the stem or root.

Structural Organisation in Animals

• Animal tissues are broadly classified into four types: epithelial, connective, muscular, and neural.
• Epithelial tissue covers the body surface and lines body cavities and organs.
• Connective tissue supports and connects various tissues and organs.
• Muscular tissue is responsible for movement.
• Neural tissue conducts nerve impulses.
• Organs are made up of different tissues organized to perform a specific function.
• Earthworms, cockroaches, and frogs are common examples used to study animal morphology and anatomy.

Cell Structure and Function

• The cell is the fundamental structural and functional unit of life.
• Prokaryotic cells lack a membrane-bound nucleus and organelles, while eukaryotic cells have a nucleus and membrane-bound organelles.
• The cell membrane is a selectively permeable barrier that controls the movement of substances into and out of the cell.
• The cell wall provides support and protection to plant cells, bacteria, and fungi.
• Organelles such as the endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, and chloroplasts perform specific functions within the cell.
• The nucleus contains the cell's genetic material (DNA) and controls cell activities.

Biomolecules

• Biomolecules are organic molecules that are essential for life, including carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates provide energy and structural support.
• Lipids store energy, form cell membranes, and act as hormones.
• Proteins perform a wide range of functions, including catalyzing reactions, transporting molecules, and providing structural support.
• Nucleic acids (DNA and RNA) store and transmit genetic information.
• Enzymes are biological catalysts that speed up chemical reactions in cells.

Cell Cycle and Cell Division

• The cell cycle is the sequence of events that a cell goes through from one division to the next. It includes interphase (G1, S, G2 phases) and mitosis (M phase).
• Mitosis is the process of cell division that results in two identical daughter cells.
• Meiosis is the process of cell division that produces four haploid gametes (sex cells) from a diploid cell. It involves two rounds of division (meiosis I and meiosis II).
• Significance involves growth, repair, and asexual reproduction (Mitosis), and genetic diversity through crossing over and independent assortment (Meiosis).

Transport in Plants

• Plants transport water, minerals, and nutrients through the xylem and phloem.
• Water is absorbed by the roots through osmosis and transported upwards through the xylem.
• Transpiration is the loss of water vapor from the leaves, which helps to pull water up the plant.
• Phloem transports sugars produced during photosynthesis from the leaves to other parts of the plant in a process called translocation.

Mineral Nutrition

• Plants require essential mineral nutrients for growth and development.
• Macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium, sulfur) are needed in large amounts, while micronutrients (iron, manganese, zinc, copper, boron, molybdenum, chlorine) are needed in small amounts.
• Nitrogen fixation is the conversion of atmospheric nitrogen into ammonia, which can be used by plants.

Photosynthesis in Higher Plants

• Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose.
• Chlorophyll is the main pigment involved in photosynthesis.
• Photosynthesis occurs in two stages: the light-dependent reactions (in the thylakoid membranes) and the light-independent reactions (Calvin cycle in the stroma).
• C4 plants have adaptations to minimize photorespiration in hot, dry environments.

Respiration in Plants

• Cellular respiration is the process by which cells break down glucose to release energy in the form of ATP.
• Glycolysis is the breakdown of glucose into pyruvate in the cytoplasm.
• The Krebs cycle (citric acid cycle) occurs in the mitochondria and generates ATP, NADH, and FADH2.
• The electron transport chain (ETC) is located in the inner mitochondrial membrane and uses electrons from NADH and FADH2 to generate a proton gradient, which drives ATP synthesis (oxidative phosphorylation).

Plant Growth and Development

• Plant growth is an irreversible increase in size or number of cells.
• Plant development includes all the changes that a plant undergoes during its life cycle.
• Plant hormones (auxins, gibberellins, cytokinins, ethylene, abscisic acid) regulate various aspects of plant growth and development.
• Photoperiodism is the response of plants to the duration of light and darkness, which affects flowering.
• Vernalization is the exposure of plants to low temperatures to promote flowering.

Digestion and Absorption

• The human digestive system consists of the alimentary canal (mouth, esophagus, stomach, small intestine, large intestine, anus) and associated digestive glands (salivary glands, liver, pancreas).
• Digestion involves the breakdown of complex food molecules into simpler ones that can be absorbed.
• Absorption is the process by which digested food molecules pass from the alimentary canal into the blood or lymph.
• Different enzymes secreted by the digestive glands break down carbohydrates, proteins, and fats.

Breathing and Exchange of Gases

• Respiration is the process by which organisms obtain oxygen and release carbon dioxide.
• The human respiratory system consists of the nasal passages, pharynx, larynx, trachea, bronchi, and lungs.
• Gas exchange occurs in the alveoli of the lungs, where oxygen diffuses into the blood and carbon dioxide diffuses out.
• Breathing is controlled by the respiratory center in the brain.

Body Fluids and Circulation

• Blood is a fluid connective tissue that transports oxygen, nutrients, hormones, and waste products.
• The heart is a muscular organ that pumps blood throughout the body.
• Blood vessels (arteries, veins, capillaries) carry blood to and from the heart.
• Lymph is a fluid that circulates in the lymphatic system and helps to remove waste products and protect against infection.
• The circulatory system transports oxygen, nutrients, hormones, and waste products throughout the body.

Excretory Products and Their Elimination

• Excretion is the process of removing waste products from the body.
• The human excretory system consists of the kidneys, ureters, urinary bladder, and urethra.
• The kidneys filter blood and produce urine, which contains waste products such as urea and creatinine.
• The nephron is the functional unit of the kidney responsible for filtering blood and forming urine.

Locomotion and Movement

• Movement is a characteristic feature of living organisms.
• Types of movement include amoeboid, ciliary, and muscular movements.
• The human skeletal system consists of bones and cartilage that provide support and protection.
• Muscles are responsible for movement and are attached to bones by tendons.
• Joints are points where two or more bones meet.

Neural Control and Coordination

• The nervous system controls and coordinates body functions.
• The human nervous system 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 that transmit nerve impulses.
• The brain is the control center of the nervous system.
• The spinal cord transmits nerve impulses between the brain and the rest of the body.

Chemical Coordination and Integration

• The endocrine system coordinates body functions through hormones.
• Hormones are chemical messengers produced by endocrine glands and transported in the blood to target tissues.
• Major endocrine glands include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries (in females), and testes (in males).
• Hormones regulate various aspects of metabolism, growth, development, and reproduction.

Reproduction in Organisms

• Reproduction is the process by which organisms produce offspring.
• Asexual reproduction involves a single parent and produces genetically identical offspring.
• Sexual reproduction involves two parents and produces offspring with genetic variation.
• Different modes of asexual reproduction include binary fission, budding, fragmentation, and spore formation.

Sexual Reproduction in Flowering Plants

• Flowers are the reproductive structures of angiosperms.
• Pollination is the transfer of pollen grains from the anther to the stigma.
• Fertilization is the fusion of the male and female gametes to form a zygote.
• The ovule develops into a seed, and the ovary develops into a fruit.

Human Reproduction

• The human reproductive system consists of the male and female reproductive organs.
• The male reproductive system includes the testes, vas deferens, seminal vesicles, prostate gland, and penis.
• The female reproductive system includes the ovaries, fallopian tubes, uterus, vagina, and mammary glands.
• Gametogenesis is the formation of gametes (sperm and egg).
• Fertilization is the fusion of the sperm and egg to form a zygote.
• Pregnancy (gestation) is the period from fertilization to birth.
• Parturition is the process of childbirth.

Principles of Inheritance and Variation

• Genetics is the study of heredity and variation.
• Genes are the units of heredity that determine traits.
• Alleles are alternative forms of a gene.
• Mendel's laws of inheritance include the law of dominance, the law of segregation, and the law of independent assortment.
• Chromosomes are structures that carry genes.
• Mutations are changes in the DNA sequence that can lead to variations.

Molecular Basis of Inheritance

• DNA is the genetic material in most organisms.
• The structure of DNA is a double helix.
• DNA replication is the process by which DNA is copied.
• Transcription is the process by which RNA is synthesized from DNA.
• Translation is the process by which proteins are synthesized from RNA.
• The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA) is translated into proteins.

Evolution

• Evolution is the process by which populations of organisms change over time.
• Evidence for evolution includes fossils, comparative anatomy, embryology, and molecular biology.
• Natural selection is the mechanism by which organisms with advantageous traits are more likely to survive and reproduce.
• Speciation is the process by which new species arise.

Human Health and Disease

• Health is a state of complete physical, mental, and social well-being.
• Disease is any condition that impairs the normal functioning of the body.
• Pathogens are disease-causing agents.
• Immunity is the ability of the body to resist infection.
• Common human diseases include infectious diseases (caused by pathogens) and non-infectious diseases (caused by genetic or environmental factors).

Strategies for Enhancement in Food Production

• Animal husbandry is the practice of breeding and raising livestock.
• Plant breeding is the process of developing new varieties of plants with desirable traits.
• Single-cell protein (SCP) is protein derived from microorganisms.
• Tissue culture is the growth of plant or animal cells or tissues in a nutrient medium under sterile conditions.

Microbes in Human Welfare

• Microbes are microorganisms that include bacteria, fungi, viruses, and protozoa.
• Microbes play important roles in various aspects of human welfare, including food production, medicine, and environmental cleanup.
• Antibiotics are drugs that kill or inhibit the growth of bacteria.
• Biogas is a mixture of gases produced by the anaerobic digestion of organic matter.
• Biocontrol agents are organisms used to control pests and diseases.

Biotechnology: Principles and Processes

• Biotechnology is the use of living organisms or their products to create useful products or processes.
• Genetic engineering is the process of altering the genetic material of an organism.
• Recombinant DNA technology involves combining DNA from different sources.
• Restriction enzymes are enzymes that cut DNA at specific sequences.
• DNA ligase is an enzyme that joins DNA fragments together.

Biotechnology and Its Applications

• Biotechnology has numerous applications in various fields, including medicine, agriculture, and industry.
• Biotechnology is used to produce genetically modified crops with improved traits.
• Biotechnology is used to produce drugs and vaccines.
• Biotechnology is used in gene therapy to treat genetic disorders.
• Biotechnology is used in environmental remediation to clean up pollutants.

Organisms and Populations

• Ecology is the study of the interactions between organisms and their environment.
• A population is a group of individuals of the same species living in the same area.
• A community is a group of interacting populations in the same area.
• An ecosystem is a community of organisms and their physical environment.
• Factors affecting population growth include birth rate, death rate, immigration, and emigration.

Ecosystem

• An ecosystem consists of biotic (living) and abiotic (non-living) components.
• Producers are organisms that produce their own food through photosynthesis.
• Consumers are organisms that obtain food by eating other organisms.
• Decomposers are organisms that break down dead organic matter.
• Food chains and food webs represent the flow of energy through an ecosystem.
• Ecological pyramids show the relative amounts of energy or biomass at different trophic levels.

Biodiversity and Conservation

• Biodiversity is the variety of life on Earth, including genetic diversity, species diversity, and ecosystem diversity.
• Biodiversity is important for maintaining ecosystem stability and providing ecosystem services.
• Threats to biodiversity include habitat loss, pollution, overexploitation, and invasive species.
• Conservation efforts include protecting habitats, managing populations, and controlling invasive species.

Environmental Issues

• Environmental pollution is the contamination of the environment by pollutants.
• Air pollution is caused by the release of harmful substances into the atmosphere.
• Water pollution is caused by the release of pollutants into bodies of water.
• Soil pollution is caused by the contamination of soil by pollutants.
• Climate change is a long-term change in the Earth's climate, primarily caused by the increase in greenhouse gases in the atmosphere.
• Ozone depletion is the thinning of the ozone layer in the stratosphere, which protects the Earth from harmful UV radiation.
• Strategies for addressing environmental issues include reducing pollution, conserving resources, and promoting sustainable development.