Defensive Strategies in Organisms

The central nervous system (CNS) is made up of the brain and spinal cord. It integrates information from the body and controls voluntary and involuntary actions.

The peripheral nervous system (PNS) is composed of nerves and ganglia that extend from the CNS and connect it to the rest of the body.

Gray matter consists of neuron cell bodies, dendrites, and unmyelinated axons. It's responsible for processing information.

White matter consists of bundles of myelinated axons. It's responsible for transmitting information.

The motor system carries signals from the CNS to skeletal muscles, allowing for voluntary movements.

The autonomic nervous system regulates internal functions like heart rate, breathing, and digestion in an involuntary way.

A reflex is an automatic response to a stimulus, bypassing conscious control.

Cranial nerves originate in the brain and mostly terminate in organs of the head and upper body.

Hormones that dissolve in water, like insulin and thyroxine. They cannot pass through cell membranes.

Hormones that dissolve in fats, like cortisol. They can easily pass through cell membranes.

A type of gland that secretes hormones directly into the bloodstream without using ducts.

A gland that releases substances through ducts to the outside of the body, like sweat glands.

A system where the nervous system and endocrine system work together to maintain balance in the body.

A small area in the brain that links the nervous and endocrine systems, controlling hormone release from the pituitary gland.

A feedback mechanism that reduces the production of hormones when they reach a certain level.

A feedback mechanism that increases the production of hormones when a signal is received.

Blood is only partially or not at all confined to blood vessels. This system is common in insects, most molluscs, and arthropods.

Blood is confined to blood vessels, making it more efficient for larger, active animals. Examples include earthworms, squid, octopus, and all vertebrates.

The main pumping organ in the circulatory system. In vertebrates, it has two to four chambers, comprised of atria and ventricles.

Carry blood away from the heart to various parts of the body.

Carry blood back to the heart from various parts of the body.

Microscopic blood vessels where gas and nutrient exchange occurs between blood and tissues.

Blood flows through the heart twice per circuit.

The contraction phase of the heart, pushing blood out.

The relaxation phase of the heart, filling with blood.

The amount of blood pumped by the left ventricle per contraction.

The ability of a plant to adjust its structure in response to its environment.

A single layer of cells that covers the outer surface of a plant.

The specialized tissues that transport water and nutrients throughout a plant.

The tissue that fills the space between the dermal and vascular tissues, performing functions like photosynthesis and storage.

A plant cell that can de-differentiate and develop into a complete new organism.

A plant cell that can develop into new tissues but not a whole new organism.

The outermost layer of a leaf, covered in a waxy cuticle to prevent water loss.

The photosynthetic tissue of a leaf, containing chloroplasts.

The vascular tissue responsible for transporting sugars produced during photosynthesis.

The vascular tissue responsible for transporting water and minerals from roots to the rest of the plant.

The central core of a stem, containing xylem and phloem.

A bud located at the tip of a stem, responsible for primary growth.

A bud located at the junction of a leaf and a stem, capable of developing into a lateral shoot.

A branch or shoot growing from the side of a plant stem.

Photosystem II (PSII) is a complex of proteins and pigments that absorbs light energy and uses it to split water molecules, releasing oxygen and transferring electrons to the primary electron acceptor.

Photosystem I (PSI) is another complex of proteins and pigments involved in light-dependent reactions. It receives electrons from PSII, absorbs light energy, and uses it to transfer electrons to NADP+ (nicotinamide adenine dinucleotide phosphate) forming NADPH, a reducing agent for the Calvin cycle.

The primary electron acceptor is a molecule that receives electrons from PSII or PSI, initiating the electron transport chain.

Chemiosmosis is the movement of protons (H+) across a membrane, from an area of high concentration to an area of low concentration, driven by an electrochemical gradient. This process powers ATP synthesis.

Photophosphorylation is the process of converting light energy into chemical energy in the form of ATP. This occurs during the light-dependent reactions of photosynthesis.

The Calvin cycle, also known as the dark reactions, is a series of biochemical reactions that use the energy from ATP and NADPH (produced in the light-dependent reactions) to fix carbon dioxide (CO2) into sugar molecules. The cycle occurs in the stroma of chloroplasts.

Carbon fixation is the initial step of the Calvin cycle, where CO2 is incorporated into an organic molecule, ribulose biphosphate (RuBP), by the enzyme Rubisco.

C4 photosynthesis is an adaptation found in some plants that increases the efficiency of carbon dioxide uptake. It involves a preliminary step where CO2 is fixed by the enzyme PEP carboxylase in mesophyll cells, producing a 4-carbon compound that is transported to bundle sheath cells for the Calvin cycle.

A process in which electrons are transferred from NADH and FADH2 to oxygen, generating a proton gradient across the mitochondrial membrane. This gradient drives the production of ATP, the energy currency of cells.

The process of energy production in the presence of oxygen. It involves glycolysis, the Krebs cycle, and oxidative phosphorylation.

Small openings on the surface of leaves that allow for gas exchange, primarily carbon dioxide uptake and water vapor release.

The loss of water vapor from plants through their leaves, primarily through stomata.

The pressure exerted by water within plant cells that helps maintain their rigidity and shape.

The condition of a plant when its cells lose water, resulting in wilting and drooping.

The movement of water and nutrients through a plant, driven by root pressure and transpiration pull.

The theory that explains how energy from electron transport is used to create a proton gradient across a membrane, which then drives ATP synthesis via ATP synthase.

Chemical elements absorbed from the soil as inorganic ions that are essential for plant growth and development.

Nutrients required in relatively large amounts by plants, including carbon, oxygen, hydrogen, nitrogen, phosphorus, and sulfur.

Nutrients required only in trace amounts by plants, including chlorine, iron, manganese, boron, zinc, copper, and nickel.

The process of adding essential nutrients to food to improve its nutritional value.

Fine, hair-like extensions of root epidermal cells that increase the surface area for absorption of water and nutrients from the soil.

A symbiotic relationship between plant roots and fungal hyphae, which enhances nutrient uptake and improves soil quality.

The continuous network of cell walls and intercellular spaces in a plant, through which water and dissolved nutrients can move.