Ecology: Defensive Strategies

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Questions and Answers

What is the primary function of glial cells in the nervous system?

Insulating and nourishing neurons (correct)

Transmitting electrical impulses

Connecting the brain to muscles

Generating action potentials

What is the result of the refractory period in neurons?

Prevention of backflow of action potentials (correct)

Increased neurotransmitter release

Decreased action potential speed

Enhanced sensory input

How does the myelin sheath affect action potentials?

It increases the speed of signal transmission. (correct)

It blocks voltage-gated ion channels.

It decreases the diameter of the axon.

It eliminates the need for nodes of Ranvier.

What are nodes of Ranvier crucial for during action potential propagation?

They allow action potentials to regenerate. Signup and view all the answers

What occurs at a chemical synapse when a neurotransmitter binds to the postsynaptic cell?

Ion channels in the postsynaptic cell open. Signup and view all the answers

What characterizes the resting potential of a neuron?

K+ is greater inside the cell than Na+. Signup and view all the answers

Which type of synapse comprises the majority of synapses in the nervous system?

Chemical synapse Signup and view all the answers

What is cephalization in animals?

Concentration of sensory organs at one end Signup and view all the answers

What type of animals has the simplest nervous system consisting of a nerve net?

Cnidarians Signup and view all the answers

What initiates the formation of an action potential in a neuron?

Depolarization of the membrane Signup and view all the answers

What does the central nervous system in vertebrates consist of?

Brain and spinal cord Signup and view all the answers

What role do afferent neurons play in the nervous system?

Bring information to the CNS Signup and view all the answers

Which part of the brain regulates involuntary functions such as breathing and cardiovascular activity?

Medulla oblongata Signup and view all the answers

How does the motor system differ from the autonomic nervous system?

The motor system carries signals to skeletal muscles voluntarily Signup and view all the answers

What is the composition of gray matter in the central nervous system?

Neuron cell bodies, dendrites, and unmyelinated axons Signup and view all the answers

Which statement correctly describes the autonomic nervous system?

It has an antagonistic effect on various organs. Signup and view all the answers

What are cranial nerves responsible for?

Connecting the brain with organs of the head and upper body Signup and view all the answers

What function does the cerebellum serve in the vertebrate brain?

Coordinating motor, perceptual, and cognitive functions Signup and view all the answers

What is the primary function of the kidneys in vertebrates?

To serve as the main excretory organ and regulate water balance Signup and view all the answers

How do Malpighian tubules function in terrestrial arthropods?

They remove nitrogenous waste from hemolymph and regulate water Signup and view all the answers

What does the proximal tubule primarily reabsorb?

Ions, water, and nutrients such as glucose Signup and view all the answers

Which part of the nephron is responsible for filtering blood and collecting filtrate?

Bowman's capsule Signup and view all the answers

Which statement best describes the loop of Henle in a juxtamedullary nephron?

It contributes to urine concentration in terrestrial animals. Signup and view all the answers

What is the main function of the descending loop of Henle?

Reabsorption of water through aquaporin channels Signup and view all the answers

What distinguishes the kidneys of mammals in dry environments from those of other mammals?

They have long loops of Henle to conserve water. Signup and view all the answers

What part of the kidney does the ureter connect to for urine expulsion?

Renal pelvis Signup and view all the answers

What is produced as a byproduct of metabolism in birds that helps conserve water?

Uric acid Signup and view all the answers

What is the function of the collecting duct in the nephron?

To transport urine to the renal pelvis Signup and view all the answers

Study Notes

Defensive Strategies

Organisms must defend themselves to survive and reproduce
Gaboon Viper uses sit-and-wait strategy (camouflage, ambush)
Parasites live on/in another organism; examples include micropathogens like COVID-19 and the Spanish flu.
Parasites replicate quickly
Attack/defense must outweigh the cost to the organism
Bacteria have immune defenses (CRISPR-Cas9 - clustered regularly interspaced short palindromic repeats that acts by snipping out parts of viral nucleic acid)
Animals use structural defenses like spines, thorns
Animals use foul smells, and/or foul, oily projectiles
Plants use constitutive (pre-formed, permanently present) and inductive defenses (exerts effect on nearby plants)
Constitutive examples include compounds that have a negative impact on grazing insects
Inductive examples are natural enemies of insects
Camouflage may also be called cryptic coloration
Poisons have to be consumed or sprayed/squirted onto exposed skin/eyes, etc
Venoms are often introduced by a bite/sting, often resulting in a fatal outcome.
200 snakes are venomous out of 2,000

Defensive Strategies - Immune System

Recognize invaders
Mount a response to invaders
Microbes (viruses, bacteria, and protozoa) are pathogens
All viruses and many bacteria and protozoa replicate inside cells
Some bacteria, protozoa, and larger parasites live outside cells
External defenses (skin) have very tight gap junctions between cells
Inflammatory response (increased blood supply, increased permeability of capillaries and migration of leukocytes)
Pathogens cause inflammation
Innate immunity is natural or native immunity, is rapid and non-specific, and lacking immunological memory.
Natural immunity includes myeloid-line cells that originate in bone marrow.
Soluble factors (proteins and peptides) such as the complement 30 proteins protect cells from invasion by viruses, this is made of lytic, opsonins, chemotactic and interferons
Opsonization: macromolecules attach to the surface of microbes that phagocytes, like macrophages, recognize to increase the efficiency of phagocytosis
Phagocytosis: process by which cells engulf and destroy large particles including bacteria, dead cells and foreign substances

Adaptive Immune Response

Highly specific and has immunologic memory
Strength increases with repeated exposure to pathogens
Triggered into action by antigen presentation
T-cells mature in the thymus gland
Two basic types
Helper T-cells help other cells activate their immune responses against specific pathogens.
Cytotoxic T-cells destroy infected cells
B-cells mature in bone marrow and produce humoral responses.
Plasma cells produce antibodies
Antibodies (immunoglobulins) are created.
Memory cells provide long-lasting immunity.
Major Histocompatibility Complex (MHC)
MHC1: involved in cellular responses to intrinsic antigens
MHC2: involved in humoral responses to extrinsic antigens
Antigens are usually presented to T-cells with MHC1 or MHC2.
Antibody types (IgG, IgM, IgA, IgD, and IgE) act in varied ways in the immune response.
Snake antivenoms are antibodies (immunoglobins) raised in horses, and are used to neutralize venom from one species or a variety of species.

Endemic, Epidemic, Pandemic

Endemic: a disease's constant presence in a defined geographical area (low prevalence)
Hyperendemic: a disease's constant presence with a high prevalence in all age groups
Novel Pathogen: enters a community without herd immunity and may be introduced accidentally.
R0: the reproductive rate of a pathogen.
Basis theory: susceptible to infected to recovered.
These diseases are based on population susceptible to infection, and their chance of recovering.

Osmoregulation and Excretion

Osmoregulation: maintains solute environment
Regulates gain and loss of water
Freshwater animals show adaptations reducing water uptake and conserve solutes
Desert and marine organisms face environments that can rapidly deplete water
Excretion: ridding of nitrogenous metabolites
Waste products from metabolism must be excreted.
Osmosis: diffusion across selectively permeable membranes.
High solute concentration increases movement of water across membrane.

Excretory Systems

Excretory are responsible for maintaining the internal environment.
Filtration, reabsorption, secretion, and excretion are the four key functions of excretory systems.
Systems:
Protonephridia (network of dead-end tubules containing flame bulbs; small branches in invertebrates)
Metanepridia (open-ended tubules; found in certain invertebrates like earthworms)
Malpighian tubules (insects and other terrestrial arthropods) remove nitrogenous wastes from the hemolymph. They affect osmoregulation.

Nervous System

The nervous system has three functions: sensory input, integration, and motor output.
Neurons are nerve cells that transfer information, including dendrites (highly branched extensions that receive signals), and axons (long extensions that transmits signals).
Ganglia are simple clusters of neurons.
Axons transmit signals.
Sensory information is sent to the brain.
Motor output leaves the brain or ganglia via motor neurons.
Action Potential: Resting to depolarization to rising phase, and falling phase, and undershoot, and refractory period.
Synapse: a junction between neurons allowing for cell communication.
Electrical synapses have an electrical current flowing from one neuron to the other.
Chemical synapses have a neurotransmitter carrying information through the synapse.

Brain

Gray matter consists of neuron cell bodies, dendrites, myelinated axons.
White matter consists of bundles of myelinated axons.
Peripheral nervous system (PNS) carries information into and out of the central nervous system (CNS).
Afferent neurons bring info to the CNS
Efferent neurons take info away from the CNS
Brain stem coordinates and conducts info from brain centers
Midbrain receives and integrates sensory information
Pons regulates breathing and cardiovascular activity, and swallowing, vomiting, digestion.
Cerebellum coordinates motor, perceptual, and cognitive functions

Endocrine System

Chemical Messengers, called hormones, control animal growth and development.
Hormone production usually occurs in endocrine glands.
Hormones may be:
- Polypeptides (water soluble)
- Amines (water soluble)
- Steroids (lipid soluble)
Endocrine systems coordinate metabolic activities and environmental responses, and help with survival.
- Many responses are controlled by multiple hormones working together to direct the function of cells in tissues, or organs. The actions of these hormones are dependent on multiple stages such as the production, release and interaction with target tissues.

Digestion

Nutritional needs for all animals
Biosynthesis: building molecules (for ex. essential nutrients)
Stages of food processing:
- Ingestion (mechanical digestion)
- Digestion (chemical digestion - enzymatic hydrolysis)
- Absorption (nutrient molecules enter body cells)
- Elimination (undigested material)

Respiration

Cellular respiration (chemical reactions that convert energy from food to usable energy)
Respiratory organs (flatworms use body walls, fish use gills, terrestrial arthropods use tracheae, mammals use lungs.)
Specialized surface area of organs increases gas exchange efficiency.

Circulation

Circulatory systems provide internal transport of materials.
Components:
- A transport medium
- A system of tubes (blood vessels)
- A pump (heart)
Open systems: blood not fully contained in vessels
Closed systems: blood completely contained in vessels.
Closed systems are more efficient for larger, more active animals.

Plant Physiology

Plants used for medicine
Chemicals found in plants may act as antioxidants, protect nutrients.
Development and reproduction of plants.

Photosynthesis

Autotrophs use inorganic molecules such as carbon dioxide to produce their own food
Heterotrophs acquire organic carbon molecules from other organisms
Photosynthesis captures light energy which is then converted to chemical energy.
Products of photosynthesis:
- ATP
- NADPH
- Glucose
Chloroplasts contain the photosynthetic apparatus.
Dark reaction: incorporation of CO2
Light Reaction: electron processes, and transfer and reduction.
Chlorophyll absorbs photons of light, which allows light to be captured.

Plant Nutrition and Transport

Stomata: for gas exchange
CO2 uptake is required for photosynthesis
Transpiration is loss of water. This is also related to cooling
Genetic adaptations to drought, or high light intensity are related to stomatal regulation and high stomatal density.
High stomatal density is found in plants in areas with high light intensity.

Plant Hormones

Plant hormones help regulate plant growth and development.
Growth refers to increase of size and weight, and development describes progression of the life cycles across the different stages.
Hormones are essential to the normal functioning of organisms
- Cells are regulated which affects the body
- Coordination of metabolism

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Description

Explore the various defensive strategies organisms use to survive and reproduce in this quiz. From the Gaboon Viper's ambush tactics to plants employing chemical defenses, you'll learn about fascinating adaptations in the natural world. Test your knowledge on immune defenses, camouflage, and more!