Plant Biology: Anatomy, Morphology and Structure

• These are lecture notes for General Biology 2 Midterm

Plant Biology

• Plant Anatomy involves detailed examination of structure to identify body part position, relations, structure, and function
• Plant Morphology focuses on the physical form and external structure of plants

Plant Body

• The root system is below the ground.
• The shoot system is above the ground.

Leaf

• Leaves are green, flattened, lateral structures attached to a stem and function as a primary organ in photosynthesis
• The cuticle is a waxy, protective layer on the leaf surface preventing water loss
• Guard cells regulate gas exchange and contain chloroplasts
• Mesophyll is the main site of photosynthesis, consisting of palisade and spongy layers
• The spongy layer contains chloroplasts and aids in photosynthesis while facilitating gas exchange

Monocot vs Dicot

• Monocots have 1 cotyledon, parallel leaf venation, flower parts in groups of 3, and scattered vascular bundles
• Examples of monocots include rice, corn, wheat, and banana
• Dicots have 2 cotyledons, net or reticulated venation, flower parts in groups of 4 or 5, and vascular bundles arranged in a ring
• Examples of dicots include mango, rose, sunflower, beans, and oak

Plant Nutrition

• Plant Nutrition refers to the supply and absorption of chemical compounds for plant growth and metabolism
• Plant Nutrients are essential chemicals or substances needed for plants to develop and grow

Meristems

• Meristems are plant tissues consisting of undifferentiated cells capable of indeterminate growth
• Lateral meristems are responsible for secondary growth (thickening of stems and roots).
• Apical Meristems are responsible for primary growth, producing new cells that form leaves, stems, and flowers

Vascular Tissue System

• Embedded in the ground tissue, serves as the main conducting tissues
• Xylem is responsible for water conduction through tracheids and vessels
• Phloem transports dissolved nutrients and minerals through sieve tubes and companion cells
• Palisade mesophyll is the site of photosynthesis, located on the upper leaf surface.
• Spongy mesophyll is the main site of gas exchange, located on the lower leaf surface.

Primary and Secondary Growth

• Primary Growth: Growth of the apical meristem
• Secondary Growth: Key features include epidermis, ground tissue (cortex and pith), cambium, and vascular bundles
• Auxins prevent growth in lateral buds, a condition known as apical dominance

Plant Hormones

• Plant Hormones play an important role in plant defense against pathogens
• Plant Hormones regulate development and signal networks in plants

Phytohormones and their Functions

• Abscisic acid (ABA) is for seed germination, leaf senescence, stomatal aperture, adaptation to environmental stress, embryo maturation, and plant photosystems defense
• Auxin has an antagonistic effect on disease susceptibility and resistance, defense responses against biotrophic and necrotrophic pathogens, stimulates cell elongation, loosening factors, such as elastin, induces growth of pre-existing roots
• Brassinosteroids (BR) are structurally related to animal steroid hormones for growth, development, and physiological responses, abiotic stress responses, seed germination, and reproductive development, regulate plant defense from pathogens
• Cytokinin (CK) is for long-distance root-to-shoot signals for N assimilation, seed development of stem-cell related genes, cell differentiation, and chloroplast formation
• Ethylene (ET) has defense from necrotrophic pathogens and herbivore insects, root hair proliferation and elongation from low iron and lateral root growth of potassium, fruit ripening
• Gibberellins (GA) respond to nutritional limitation and has partial regulation of Pi signaling
• Jasmonic acid (JA) has defense from necrotrophic pathogens and herbivore insects such as cat beetles, leafhoppers, and spider mites
• Salicylic Acid (SA) is for activation of defense response from biotrophic and hemi-biotrophic pathogens establish systemic acquired resistance, inhibits seed germination, increases vigor

Flower parts

• Stamen is the male part, consisting of anther and filament
• Pistil/Carpel is the female part, consisting of stigma, style, ovary, and ovule
• Other parts include petals, sepal, and pedicel

Seed and Fruit

• A seed is a mature ovule
• A fruit is a seed-bearing structure of a plant, which is formed from the ovary

Roots

• Modified roots include adventitious roots, which arise aboveground
• Storage roots hold food

Animal Biology

• Morphoanatomy is the study of anatomical forms and structures emphasizing characteristics useful in distinguishing species
• Bilateral symmetry divides an organism into mirror image halves
• Radial symmetry allows an organism to be divided into similar halves by passing a plane at any angle along a central axis
• Asymmetry means not identical on both sides of a central line

Invertebrates

• Poriferans (sponges) have a body made up of tiny pores and contain spicules that serve as their skeleton
• Echinoderms have a spiny rigid surface and tube feet for locomotion such as starfish and sea urchins
• Mollusks have a soft, unsegmented body and strong muscular feet, for example, snails and shellfish
• Arthropods have hardened exoskeleton and jointed appendages
• Cnidarians have stinging cells called cnidocytes, including Medusa (free-swimming coelenterate, jellyfish) and Polyp (Hydra)
• Platyhelminthes (tapeworms) have a flattened body
• Nematodes (roundworms) have a long, smooth, and unsegmented body
• Annelids (earthworm) have a body segmented internally and externally

Vertebrates - Chordata

• Chordata have a single, hollow nerve cord beneath dorsal surface
• Chondrichthyes are cartilaginous fish like sharks and rays
• Osteichthyes are bony fish, including both marine and freshwater fish
• Class Aves are flying and non-flying birds with feathers, wings, and are warm-blooded
• Amphibians live on land and water
• Reptiles (iguana, alligator, crocodile, lizards) are cold-blooded with scaly skins
• Mammals are warm-blooded with mammary glands, hair, jaw, and ear bones, and a 4-chambered heart

Animal Reproduction and Development

• Asexual reproduction produces individuals are exact clones of the parent with identical genetic makeup
• Sexual reproduction produces individuals formed from the combination of gametes to form a genetically unique offspring
• Gametogenesis is the formation of egg and sperm
• Males produce testosterone
• Females produce estrogen and progesterone
• Regeneration involves the production and differentiation of new tissues to replace missing and damaged parts of the body
• Budding is from an outgrowth on the parent's body for example, Hydra and polyps
• Parthenogenesis involves an activated unfertilized egg that undergoes mitosis without cytokinesis

Anisogamy vs Isogamy vs Oogamy

• Anisogamy is the fusion of gametes in dissimilar sizes in which male and female gametes are present and not distinguishable
• Both male and female gametes are either motile or immotile
• Isogamy is the fusion of gametes in similar size in which male and female gametes are present
• Oogamy is the fusion of large immotile female gametes with small motile male gametes
• The egg cell is immotile, and the sperm cell is motile
• Primary oocyte cells have primary function to divide by meiosis process.
• Monoecious animals possess both male and female reproductive organs, allowing self-fertilization (hermaphroditic)
• Dioecious animals have male reproductive organs in one individual and female in another
• Self-fertilization is effected by the union of egg cell and sperm cell from the same individual
• Cross-fertilization is gametes produced by separate individuals of different kinds
• Indirect development means metamorphosis is present
• Direct development means metamorphosis is absent
• Spermatogenesis is when Testes produce testosterone
• Oogenesis is when Ovaries produce Estrogen
• Gametes- specialized cells responsible for carrying genetic information

Nervous System

• The Nervous System allows the body to respond quickly to changes in the environment by gathering, transmitting, and processing information, and sending information to muscles, glands, and organs
• A Nerve impulse involves dendrites receiving the signal; the impulse moves to the cell body (soma) where the nucleus is located, then travels down the axon toward the axon terminals
• The myelin sheath (if present) helps speed up the signal and impulse jumps between the nodes of Ranvier.
• The Central Nervous System consists of the Brain and the Spinal cord
• The Peripheral Nervous System: Somatic Nervous System (voluntary) relays information from skin, sense organs, and skeletal muscles to CNS
• Autonomic Nervous System (involuntary) regulates the body's involuntary responses

Types of responses

• Sympathetic: emergency response, fight or flight
• Parasympathetic: normal everyday conditions
• Nerve nets are nervous system of hydra
• A Neuron that transmits messages receives stimulus and carries impulses toward the cell body
• Parts of a Neuron include Dendrite, Cell Body, Axon, Schwann cells, Myelin Sheath, Node of Ranvier

Neuron types

• Sensory neurons bring messages to the CNS
• Motor neurons carry messages from CNS
• Interneurons are between sensory and motor neurons in the CNS
• The meninges are the protective layers surrounding the brain and spinal cord
• The following sequence (from the brain outward toward the skull): Pia mater, Arachnoid mater, Dura mater

Immune System

• The Immune System is responsible for defending organisms from pathogens like viruses, bacteria, fungi, etc
• Two Major Lines of Defense: innate Immunity and Acquired/Adaptive Immunity
• Innate Immunity consists of skin and mucous membrane accompanied by macrophages and other phagocytic cells, is the First line and Second line of defense
• Acquired Immunity is when lymphocytes play a central role in immune response
• B cells produce antibodies and mature in the bone marrow
• T cells attack infected cells through phagocytosis or by injecting perforins to break down and kill pathogen
• Memory B cells are a type of B-lymphocyte that remain in the body after an infection
• When the same pathogen infects the body again, these memory cells: recognize the antigen quickly, rapidly divide and produce antibodies specific to the pathogen, and result in a faster and stronger immune response
• Universal donor have type O
• Universal recipient have type AB
• A skin graft requires tissue compatibility to prevent rejection by the immune system, the best donor and type is an identical twin

Musculo-Skeletal System

• The Skeletal ensures supporting the body, protecting internal organs, and allowing for the movement of an organism
• A Hydrostatic skeleton is formed by a fluid-filled compartment within the body
• An Exoskeleton is external and a hard encasement on the surface of an organism
• An Endoskeleton is made up of hard, mineralized structures located within the soft tissue or organisms
• Bones perform several essential functions in the human body, including storage of minerals and protection of internal organs
• Bone marrow is responsible for hematopoiesis, the production of red blood cells, white blood cells, and plateles

Muscular System

• Smooth muscle has spindle-shaped, nonstriated uninucleated fibers, is involuntary, and occurs in calls of internal organs
• Cardiac muscle has striated, branched, uninucleated fibers, is involuntary, and the walls of the heart
• Skeletal muscle has striated, tubular, multinucleated fibers, is voluntary, and Attached to the skeleton
• A Sarcomere is a functional unit of muscle that contracts
• Antibodies are responsible for early stages of immunity