BIOL 1P92 Final (Prof Study Questions)
Week 7: What Characteristics Distinguish plants from their algal ancestors?
- plants are multicellular, have plastids, and primarily live on land, whereas algaue are mostly aquatic
Wk 7: What key adaptations allowed plants to survive on land?
development of a cuticle to prevent water loss, stomata for gas exchange, and structures like vascular tissue for support and transport
Wk 7: What is the significance of plastids in plant cells?
plastids, including chloroplasts, are responsible for photosynthesis and other biosynthetic processes
wk 7: How do land plants differ from their closest green algal relatives?
- land plants have multicellular tissues, alternation of generations, and specialized reproductive structures like gametangia
Wk 7: From which group of algae did land plants evolve?
land plants evolved from streptophyte algae that were similar to Charophycean algae
Wk 7: What is the haploid-dominant (zygotic) life cycle, and in which organisms is it found?
- it is a reproductive cycle where the haploid stage dominates, found in some algae
What is alternation of generations, and how does it differ from the zygotic life cycle?
- alternation of generations includes both multicellular haploid (gametophyte) and diploid (sporophyte) stages, unlike the zygotic cycle where the diploid phase is brief.
How do gametophytes function in plant reproduction?
- gametophytes produce haploid gametes through mitosis, which then fuse to form a diploid zygote
What structures protect plants gametes from desiccation?
- Gametangia (antheridia for sperm and archemonia for eggs) protect gametes
wk 7: What are the main differences between gametophytes and sporophytes?
- Gametophytes are haploid and produce gametes, while sporophytes are diploid and produce spores
Wk 7: What are the nine major phyla of plants?
Hepatophyta (liverworts)
Bryophyta (mosses)
Anthocerophyta (hornworts)
Lycophyta (lycophytes)
Pteridophyta (ferns)
Cycadophyta (cycads)
Ginkgophyta (ginkgos)
Coniferophyta (conifers)
Anthophyta (angiosperms)
What traits distinguish bryophytes from other plant groups?
They lack vascular tissue, have dominant gametophytes, and require water for sperm moveme
Wk 7: Why are bryophytes typically found in mois environments?
They need water for reproduction since their sperm are flagellated and require water to swim to the
egg
Wk 7: What adaptations do bryophytes have for reproduction?
They produce spores with tough walls, rely on water for fertilization, and have protective gametangia
Wk 7: How do liverworts differ from mosses and hornworts?
- liverworts lack true stomata, whereas mosses and hornworts possess them
Wk 7: What is the role of rhizoids in bryophytes?
Rhizoids anchor the plant and aid in water absorption, but they do not function like true roots
Wk 7: What is the significance of vascular tissue in plants?
Vascular tissue (xylem and phloem) transports water, nutrients, and food, allowing plants to grow large
How do lycophytes differ from pteridophytes?
Lycophytes have microphylls (small leaves with a single vein), while pteridophytes have megaphylls (larger leaves with multiple veins
What features define seedless vascular plants?
They possess vascular tissue but reproduce via spores instead of seeds
How do lycophytes transport water and nutrients?
- they use vascular tissue, specifically xylem for water transport and phloem for nutrient distribution.
Wk 7: What are tracheophytes, and what adaptations do they have for land?
Tracheophytes are plants with vascular tissue, enabling efficient water transport and structural support
Why were lycophytes and pteridophytes more abundant in the past?
They dominated Carboniferous forests, forming vast swampy ecosystems, but declined as climate changed
What structures in ferns house spores?
Spores are housed in sporangia, often grouped into clusters called sori
How do the sporophyte and gametophyte stages differ in ferns?
The sporophyte is the dominant stage, while the gametophyte is small and free-living
Wk 7: What role do sori play in fern reproduction
Sori contain sporangia that produce spores for reproduction
What climat changes during the Carboniferous period led to the dominance of gymnosperms
- cooler and drier conditions caused the decline of lycophytes and pteridophytes, allowing gymnosperms to diversify
What are the four major groups of gymnosperms?
Cycadophyta (cycads), Ginkgophyta (ginkgoes), Coniferophyta (conifers), and Gnetophyta
(gnetophytes)
Why are gymnosperm seeds called "naked seeds"?
they are not enclosed by fruit, unlike angiosperm seeds
What reproductive adaptations do gymnosperms have
- they produce seeds and pollen, allowing fertilization without water
What are some common characteristics of conifers?
- needle-like leaves
- produce cones
- many are evergreen
Wk 7: What is the main advantage of seeds over spores?
Seeds provide protection, nourishment, and can remain dormant until favourable conditions
arise.
How do ovules develop into seeds
after fertilization, the ovule matures into a seed containing an embryo, nutritive tissue, and a protective seed coat.
What is heterospory, and how is it beneficial?
The production of two types of spores (microspores and megaspores) increases cross-fertilization and genetic diversity
What is the function of a pollen tube?
- it delivers sperm directly to the egg, eliminating the need for water in fertilization
How do gymnosperms disperse their seeds
seeds are dispersed by wind, animals, or other environmental factors
what distinguishes angiosperms from gymnosperms
- angiosperms have flowers and fruits, which protect and aid in seed dispersal
what are the two major groups of angiosperms
Monocots (one cotyledon) and eudicots (two cotyledons
How do flowers contribute to angiosperm success?
they attract pollinators, increasing reproductive efficiency and genetic variation
What role does endosperm play in angiosperm seeds
it provides nutrients for the developing embryo
What is double fertilization in angiosperms
One sperm fertilizes the egg (forming an embryo), while the other forms the triploid endosperm
How do fruits aid in seed dispersal
fruits attract animals, who eat and spread seeds, or use wind/water for dispersal
What are some key differences between monocots and eudicots
monocots have parallel-veined leaves, while eudicots have net-veined leaves
What adaptations allow angiosperms to transport water efficiently?
they have vessel elements in their xylem, which are more efficient than tracheids
How have angiosperms co-evolved with pollinators?
- specific flower traits attract certain pollinators, increasing fertilization success
Why is seed dormancy an important adaptation?
- it allows seeds to survive unfavourable conditions and germinate at the right time
Wk 7: How did early land plants contribute to atmospheric changes?
they increased oxygen levels and helped develop soil
What is placental transfer tissue, and why is it significant?
- it allows maternal tissues to nourish developing embryos, an important evolutionary step
Why was the origin of land plants crucial for animal colonization?
plants provided oxygen and food, making land habitale for animals
How did gymnosperms and angiosperms shape modern ecosystems
- they dominate forests, influence climate, and support diverse life forms
What major advantage do angiosperms have over gymnosperms?
- more efficient reproduction via flowers, fruits, and diverse pollination strategies
Wk 8: From what type of ancestor did animals evolve?
animals evolved from a protist similar to choanoflagellates
Wk 8: What are choanoflagellates, and why are they important?
They are single-celled protists with a flagellum surrounded by a collar of tentacles. They are the closest living relatives of animals and resemble sponge choanocyte
What are the defining characteristics of animals?
- multicellular, heterotrophic, lack cell walls, motile at some stage, and reproduce sexually or asexually
What structural component provides support in animals
- the extracellular matrix (ECM), composed mainly of collagen
What types of cell junctions are unique to animals?
anchoring, tight, and gap junctions
What are the three main modes of animal feeding?
Suspension feeding (filtering particles from water)
bulk feeding (eating large food pieces),
fluid feeding (sucking sap or body fluids)
Why is movement important for animals?
It helps in food acquisition, escaping predators, and finding mate
What type of tissue is unique to animals?
Muscle tissue, which allows for movement
How do sessile animals, such as barnacles, adapt to movement?
- they have moving appendages or a mobile larval stage
What is cephalization, and why is it important?
Cephalization is the concentration of sensory and nervous structures at the anterior end of the body, allowing better coordination and response to stimuli
How do most animals reproduce?
Most animals reproduce sexually, with small, mobile sperm fertilizing a larger egg to form a zygote.
What is the difference between internal and external fertilization?
internal fertilization occurs inside the female body, while external fertilization occurs in water
What is metamorphosis, and why is it beneficial?
metamorphosis is a developmental change from juvenile to adult form (e.g. tadpole to frog)
- reduces competition and aids in dispersal
Wk 8: What role do Hox genes play in animal development?
Hox genes control body patterning along the anterior-posterior axis
What is the significance of the Cambrian explosion
- It was a rapid increase in animal diversity (~533-525 million years ago), leading to the appearance
of most major animal group
What are the three embryonic germ layers?
Endoderm (forms the gut lining)
mesoderm (forms muscles and organs)
ectoderm (forms the skin and nervous system)
What is the difference between diploblastic and triploblastic animals?
Diploblastic animals have two germ layers (ectoderm and endoderm), while triploblastic animals have all three (including mesoderm)
What are the two types of body symmetry in animals?
Radial symmetry (e.g., jellyfish) and bilateral symmetry (e.g., human
What is the advantage of bilateral symmetry?
It allows for cephalization and more efficient movement
What are the terms used to describe body orientation in bilaterally symmetrical animals?
Dorsal (back), ventral (front or belly), anterior (head), and posterior (tail)
What are the three types of body cavities in animals?
Acoelomates (no body cavity), pseudocoelomates (cavity not fully lined by mesoderm), and
coelomates (true coelom fully lined by mesoderm).
What is an example of an acoelomate animal?
Flatworms (Phylum Platyhelminthes).
What is an example of a pseuodocoelomate animal?
Roundworms (Phylum Nematoda).
Why is a coelom important?
It provides space for organ development and allows better movement and circulation
What evolutionary advantages helped animals diversify?
The development of tissues, body symmetry, cephalization, and body cavities allowed for greater complexity and adaptability
What are the two main groups of bilaterian animals based on embryonic development?
o Protostomes and deuterostomes
How do protostomes and deuterostomes differ in nervous system placement?
Protostomes have a ventral nervous system, while deuterostomes have a dorsal nervous system.
What is segmentation, and why is it important?
Segmentation is the repetition of body structures along the anterior-posterior axis. It allows for greater flexibility and specialization in movement
How has molecular data changes our understanding of animal phylogeny?
It has shown that some traditional traits, such as coelom type, are unreliable for determining evolutionary relationships
What are the two major invertebrate clades identified by molecular data?
Lophotrochozoa and Ecdysozo
Which phylum is considered the earliest group of animals?
Ctenophora (comb jellies)
What are the key characteristics of ctenophores?
They have eight rows of cilia for movement, two tentacles without stinging cells, and a complete gut with an anus
Why are ctenophores considered serparate from jellyfish despite their similar appearance?
Their nervous system and gut structure evolved independently from cnidarian
What are the main characteristics of sponges (Phylum Porifera)?
They lack true tissues, have porous bodies, and rely on choanocytes for filter feeding
How do sponges reproduce?
They reproduce both sexually (hermaphroditic fertilization) and asexually (budding or fragmentation)
What are the main characteristics of cnidarians?
- sac-like body with a single opening
- radial symmetry
- specialized tissues
- stingning nematocysts
What are the two main body forms found in cnidarians?
The polyp (sessile) and medusa (free-swimming) forms
What is the function of nematocysts in cnidarians?
Nematocysts are stinging organelles used to capture prey and for defense
What is an example of a cnidarian with a life cycle that alternates between polyp and medusa stages?
The moon jelly (Aurelia)
Wk 8: Why are cnidarians considered among the simplest animals with nervous systems?
• They have a nerve net instead of a centralized brain.
What are the defining characteristics of Lophotrochozoa?
They have either a lophophore (feeding tentacles) or a trochophore larval stage
What are the three main phyla in Lophotrochozoa?
Platyhelminthes (flatworms), Mollusca (mollusks), and Annelida (segmented worms
What is unique about flatworms (Platyhelminthes)?
• They lack a coelom, have a simple digestive system, and can regenerate body par
What is an example of a mollusk with a highly developed nervous system?
Cephalopods, such as octopuses and squids
What is segmentation in annelids, and how does it benefit them?
their bodies are divided into repeated segments, allowing for efficient movement and flexibility
What is the defining feature of Ecdysozoa?
They grow by molting (ecdysis), shedding their exoskeleton
Which two major phyla belong to Ecdysozoa?
Nematoda (roundworms) and Arthropoda (insects, spiders, crustaceans
What is the difference between the body cavities of roundworms and annelids?
Roundworms have a pseudocoelom, while annelids have a true coelom
Why are arthropods considered the most diverse animal phylum?
They have specialized body segments, exoskeletons, and adaptations for various environments
What is an example of an arthropod adaptation that led to their success?
The evolution of jointed appendages for movement and manipulation
What are the main characteristics of Playhelminthes (flatworms)?
They are acoelomate, have three germ layers, and can be free-living or parasitic
What are the three germ layers in flatworms?
Endoderm (digestive system), mesoderm (muscles and reproductive organs), and ectoderm (nervous system and epidermis)
What unique feeding structure do Rotifers possess?
o A ciliated crown called the corona.
What is the function of the lophophore in Bryozoans and Brachiopods?
o It is used for filter feeding and gas exchange.
How do Bryozoans and Brachiopods differ?
Bryozoans are small colonial animals, while Brachiopods are marine animals with dorsal and ventral shells.
What are the four main major classes of Mollusca?
Bivalvia (clams, oysters), Gastropoda (snails, slugs), Cephalopoda (squid, octopuses), and Polyplacophora (chitons).
What body features are shared among mollusks?
A mantle, a radula (except in bivalves), a visceral mass, and a foot
What is the function of the radula in mollusks?
= a specialized feeding structure used for scraping or cutting foo
What type of circulatory system do cephalopods have?
A closed circulatory system, unlike other mollusks which have an open system
Which class of mollusks includes the most intelligent invertebrates?
Cephalopoda (e.g., octopuses and squids).
What is segmentation, and why is it important in annelids?
Segmentation allows for efficient movement and flexibility
What are two major groups of annelids?
Errantia (mobile marine worms) and Sedentaria (earthworms, leeches, and tube worm
What is the function of the cuticle in annelids?
• It provides protection and helps retain moisture
How do earthworms contribute to soil health?
• They aerate the soil and decompose organic material
What is the difference between Errantia and Sedentaria annelids?
Errantia are active predators, while Sedentaria are burrowing or filter-feeding worms
What are the defining characteristics of Phylum Nematoda?
• They are pseudocoelomates, undergo ecdysis, and include both free-living and parasitic species
What human diseases are caused by nematodes?
Hookworm infections, pinworm infections, and elephantiasis (caused by Wuchereria bancrofti).
What are the four main arthropod subphyla?
Chelicerata (spiders, scorpions)
Myriapoda (millipedes, centipedes)
Crustacea (crabs, shrimp)
Hexapoda (insects).
What are the key features of arthropods that contribute to their success?
Their segmented bodies with specialized appendages and a chitinous exoskeleton.
How do arthropods grow despite having an exoskeleton?
They molt their exoskeleton in a process called ecdysis
Wk 9: What is a deuterostome?
A deuterostome is an animal in which the blastopore develops into the anus, with the mouth forming later
Which two major phyla belong to Deuterostomia?
Echinodermata and Chordata
What are the key characteristics of Phylum Echinodermata?
- They have bilateral symmetry as juveniles
- modified radial symmetry in adults
- an endoskeleton covered with spines, a water vascular system (tube feet) for movement
- the ability to regenerate lost body part
How do echinoderms perform respiration and excretion?
Through diffusion across their body surface
What is autotomy in echinoderms?
The ability to intentionally detach body parts, which can later regenerate
What are the five main classes of echinoderms?
Asteroidea (sea stars)
Ophiuroidea (brittle stars)
Echinoidea (sea urchins, sand dollars),
Crinoidea (sea lilies, feather stars)
Holothuroidea (sea cucumbers)
How do sea stars feed on bivalves?
o They use their tube feet to pry open the shell and evert their stomachs to digest the prey externally
What is unique about brittle stars compared to sea stars?
They have long, slender arms and do not use tube feet for locomotion
What is the primary mode of movement in echinoderms?
They use a water vascular system that controls tube feet for locomotion
What is the function of pedicellariae in sea urchins?
o They help keep the body surface free of debris and deter predators
What are the four defining features of chordates?
A notochord, a dorsal hollow nerve cord, pharyngeal slits, and a postanal tail
Which chordates are invertebrates?
Urochordates (tunicates) and Cephalochordates (lancelets)
What is the function of the notochord in chordates?
It provides structural support and is replaced by the vertebral column in vertebrates
How do lancelets (Cephalochordata) feed?
• They are filter feeders, drawing in water and trapping food particles in mucus-covered gill slits
What is a unique feature of tunicates (Urochordata)?
• Adults are sessile filter feeders, but their larvae exhibit chordate characteristics, including a notochord and tail
What are the key characteristics that distinguish vertebrates from other chordates?
A vertebral column, a cranium, an endoskeleton of bone or cartilage, multiple clusters of Hox genes, and complex organ system
How did vertebrates evolve from chordate ancestors?
• Through the duplication of genes that regulate development, leading to increased complexity and specialization
What role do Hox genes play in vertebrate development?
• They regulate body patterning and the development of specialized structures
What is the function of the vertebral column in vertebrates?
• It replaces the notochord and provides structural support, allowing for greater mobility
What are the three main regions of the vertebrate brain?
• The forebrain, midbrain, and hindbrain
What are Cyclostomes, and what distinguishes them from other vertebrates?
• Cyclostomes are jawless vertebrates, including hagfish and lampreys. They lack jaws and paired fins.
What are the key features of Chondrichthyes (cartilaginous fishes)?
• They have a skeleton made of cartilage, internal fertilization, well-developed fins, and no swim bladder.
How do actinopterygian (ray-finned) fish differ from sarcopterygian (lobe-finned) fish?
• Ray-finned fish have thin, flexible fins supported by bony rays, while lobe-finned fish have fleshy,
muscular fins with bony extensions
What adaptation allows amphibians to live on land but still depend on water?
• They have lungs for breathing air but require water for reproduction and have moist skin for gas
exchange.
How do birds (Aves) differ from other reptiles?
• Birds have feathers, hollow bones, air sacs, and a high metabolic rate, making them adapted for flight.
What is Tiktaalik rosae, and why is it important in vertebrate evolution?
o Tiktaalik rosae, or the "fishapod," is a transitional fossil that shows features of both fish
and early tetrapods, including lungs, sturdy fins, and a broad skull with eyes on
What key adaptations helped early tetrapods transition to life on land?
- Strong vertebral column and girdles
- stout fins for crawling
- lungs
- nostrils
- modified sensory systems.
Wk 9: What are the three main groups of living amphibians?
Anura (frogs and toads), Urodela (salamanders and newts), and Gymnophiona (caecilians).
What type of heart do amphibians have, and why is it significant?
Amphibians have a three-chambered heart, which partially separates oxygenated and deoxygenated blood.
Why do amphibians require water for reproduction?
They have external fertilization, and their eggs lack shells, making them prone to desiccation.
What is the significance of the amniotic egg in vertebrate evolution?
o It allowed tetrapods to reproduce away from water, providing protection and nutrients for
the embryo
What are the four membranes of the amniotic egg, and what are their functions?
o Amnion (protects embryo), yolk sac (provides nutrients), allantois (waste storage),
chorion (gas exchange)
How do the eggs of birds, reptiles, and mammals differ?
o Bird eggs have hard calcareous shells, reptile eggs have soft leathery shells, and most
mammals have no shells, with embryos developing in the uteru
Wk 9: What adaptations help amniotes conserve water?
Desiccation-resistant skin, water-conserving kidneys, and internal fertilization.
What is thoracic breathing, and why is it important for amniotes?
o It allows air to be drawn into the lungs via negative pressure, making respiration more efficient than buccal pumping
What are the five major extinct reptilian clades?
Ornithischian dinosaurs, Saurischian dinosaurs, flying reptiles (pterosaurs), ichthyosaurs, and plesiosaurs
Why are birds classified as reptiles in modern taxonomy?
• Birds evolved from theropod dinosaurs and share traits such as scales, egg-laying, and skeletal similarities
What adaptations allow birds to fly?
Feathers, hollow bones, air sacs for efficient respiration, and a four-chambered heart
How do birds differ from other reptiles in thermoregulation?
• Birds are endothermic (generate their own heat), while most reptiles are ectothermic (rely on
external heat sources).
What is the function of the keel in birds?
It provides an attachment site for strong flight muscles
When did mammals first appear, and when did they diversify?
• Mammals first appeared about 225 million years ago and diversified after the extinction of the
dinosaurs
What are the defining characteristics of mammals?
• Mammary glands, hair, specialized teeth, enlarged skulls, and three middle ear bones
How do mammalian teeth differ from reptilian teeth?
• Mammals have specialized teeth for different functions (e.g., incisors, canines, molars), while reptiles have more uniform teeth
What are the three main groups of mammals?
• Monotremes (egg-laying mammals), marsupials (pouch-bearing mammals), and eutherians (placental mammals)
What is the significance of the mammalian placenta?
It allows direct nutrient and gas exchange between mother and developing embryo, leading to longer gestation periods.
Which mammals are classified as monotremes, and what makes them unique?
Platypuses and echidnas; they lay eggs and lack nipples, secreting milk through specialized skin glands
What is the only marsupial found in North America?
The opossum
What are the four major clades of placental mammals, and what are some examples?
Afrotheria (elephants, manatees), Xenarthra (sloths, anteaters), Euarchontoglires (primates, rodents), Laurasiatheria (whales, bats, carnivores)
How did continental drift influence mammalian evolution?
It separated populations, leading to the independent evolution of unique mammalian lineages in different continents
What adaptations allow mammals to thrive in diverse environments?
Fur for insulation, endothermy for temperature regulation, specialized limbs for various locomotion types, and complex brains for problem-solving
What are the four primary tissue types in animals?
Epithelial
Connective
Muscle
Nervous tissue
What is the main function of epithelial tissue?
Epithelial tissue covers body surfaces and lines organs and cavities, providing protection and enabling absorption and secretion
How does connective tissue differ from epithelial tissue?
Connective tissue typically has fewer cells and more extracellular matrix, offering structural support and binding other tissues, whereas epithelial tissue consists of tightly packed cells forming protective layers
What are the three types of muscle tissue, and where is each found?
Skeletal muscle (attached to bones), cardiac muscle (in heart walls), and smooth muscle (in
walls of internal organs like the intestines and blood vessels).
5. Nervous tissue detects stimuli and transmits electrical impulses for communication and
coordination within the body.
6. Homeostasis is the process of maintaining a stable internal environment despite changes in
What is the primary role of nervous tissue?
Nervous tissue detects stimuli and transmits electrical impulses for communication and coordination within the body
Define homeostasis.
Homeostasis is the process of maintaining a stable internal environment despite changes in the external environment
What is a negative feedback loop in physiological processes?
A negative feedback loop is a control mechanism where a change in a variable triggers a response that counteracts the original change, maintaining balance.
Provide an example of a negative feedback mechanism in the human body.
Regulation of body temperature: if body temperature increases, mechanisms such as sweating and vasodilation cool the body down.
What is a positive feedback loop, and how does it differ from a negative feedback loop?
A positive feedback loop amplifies the direction of the change, as opposed to negative feedback, which works to negate the change.
Give an example of a positive feedback mechanism in the human body?
The release of oxytocin during childbirth increases uterine contractions, which stimulates more oxytocin release until delivery.
What is the hierarchical organization of the animal body from simplest to most complex?
Cells → Tissues → Organs → Organ systems → Organism
What is the role of the extracellular matrix in connective tissue?
The extracellular matrix provides structural support, helps cells bind together, and plays roles in signaling and tissue function.
How do animals use conformers versus regulators in coping with environmental change?
Conformers allow internal conditions to vary with the environment; regulators maintain constant internal conditions regardless of external changes.
Why is homeostasis important for enzyme function?
Homeostasis keeps internal temperatures and pH within a range optimal for enzyme activity; deviations can reduce enzymatic efficiency
What is an example of a physiological parameter tightly regulated by homeostasis?
Blood glucose levels, pH, and body temperature are examples of tightly regulated
What role does the hypothalamus play in thermoregulation?
The hypothalamus detects changes in body temperature and activates mechanisms like shivering or sweating to restore balance.
How does vasodilation help in cooling the body?
Vasodilation increases blood flow near the skin, allowing heat to dissipate and thereby cooling the body
What are set points in homeostatic control systems?
Set points are the target values around which physiological parameters are maintained by homeostatic systems
How does feedforward regulation differ from feedback regulation?
Feedforward regulation anticipates changes and adjusts physiology in advance, while feedback regulation responds after changes occur.
How does epithelial cell polarity contribute to its function?
Epithelial cells have apical and basal surfaces, allowing directional movement of substances and specialized functions such as absorption and secretion.
What is the main difference between neurons and glial cells in the nervous system?
Neurons transmit electrical signals; glial cells provide support and protection for neurons.
How does the resting membrane potential arise in a neuron?
It’s due to ion concentration differences and selective permeability, resulting in a –70 mV
charge inside.
What function does the Na⁺/K⁺-ATPase pump serve in establishing membrane potential?
It moves 3 Na⁺ out and 2 K⁺ in, helping maintain the negative internal charge
Why is the membrane more permeable to K⁺ than other ions at rest?
Because of many K⁺-specific leak channels that allow passive K⁺ movement.
What is an electrochemical gradient, and how is it formed?
It’s the combined effect of electrical charge and concentration gradient that influences ion flow.
How does the Nernst equation help predict ion movement across the membrane?
It calculates the equilibrium potential for an ion based on its gradient.
What is the threshold potential, and how does it relate to the initiation of an action potential?
It’s the membrane voltage (~–55 mV) needed to open Na⁺ channels and trigger an action potential.
Compare and contrast depolarization and hyperpolarization.
Depolarization = less negative membrane potential; hyperpolarization = more negative
What are the three types of gated ion channels, and what triggers each?
Voltage-gated (voltage change), ligand-gated (chemical signals), mechanically-gated (physical force).
What distinguishes an action potential from a graded potential?
Action potentials are all-or-none and travel far; graded potentials vary in size and decay with distance
What is the difference between the absolute and relative refractory periods?
Absolute = no new AP possible; relative = AP possible with stronger stimulus
How does the inactivation of Na⁺ channels prevent backward movement of the action potential?
Once Na⁺ channels are inactivated, they can’t reopen immediately, preventing backflo
What factors affect the speed of action potential conduction in axons?
Larger axon diameter and myelination speed up conduction.
What are the roles of oligodendrocytes and Schwann cells?
They form the myelin sheath—oligodendrocytes (CNS), Schwann cells (PNS)
How does saltatory conduction increase the efficiency of nerve signal transmission?
It lets signals "jump" between nodes of Ranvier, speeding transmission
What is the difference between electrical and chemical synapses?
Electrical = direct ion flow; chemical = neurotransmitters cross synaptic cleft
Describe the process by which neurotransmitters are released at a chemical synapse.
Ca²⁺ influx causes vesicles to release neurotransmitters into the synaptic cleft.
How do EPSPs and IPSPs affect the membrane potential of the postsynaptic neuron?
EPSPs depolarize (excite); IPSPs hyperpolarize (inhibit).
What is the difference between spatial summation and temporal summation?
Spatial = multiple inputs at once; temporal = rapid inputs at same spot.
Name the five major classes of neurotransmitters and provide one example of each.
Acetylcholine (e.g., neuromuscular junction)
biogenic amines (dopamine)
amino acids (GABA)
neuropeptides (endorphins)
gaseous transmitters (NO)
What determines whether a neurotransmitter has an excitatory or inhibitory effect?
It depends on the type of receptor the neurotransmitter binds to.
How do ionotropic and metabotropic receptors differ?
Ionotropic = direct ion channel; metabotropic = uses G-proteins and secondary messengers
What are the structural components of a GABA-A receptor, and how does it regulate neural activity?
5 protein subunits form Cl⁻ channel; regulates inhibition
How does ethanol affect GABA-A receptor function?
It enhances GABA-A activity, depressing neural function.
What is nociception, and what kind of stimuli activate nociceptors?
Nociception is pain detection from harmful stimuli like extreme temperature or cell damage.
How do thermoreceptors help maintain homeostasis?
They detect heat or cold and help regulate internal temperature.
What is a reflex arc, and how does it enable rapid responses to stimuli?
A stimulus directly causes a motor response via a simple neuron circuit
Describe the nervous system structure of cnidarians and its basic function.
Nerve net with interconnected neurons; signals spread in all directions
What is cephalization, and in which animals does it first appear?
Cephalization = concentration of sense organs at the head
- first seen in flatworms (Platyhelminthes).
How has the vertebrate brain evolved in terms of size and complexity, especially the forebrain?
Larger forebrains evolved in complex vertebrates; more folds allow more surface area and processing power.
Describe the function of the nephron and its major component.
The nephron is the functional unit of the kidney responsible for filtering blood, reabsorbing essential nutrients, and excreting waste as urine.
Major components include:
- Glomerulus: Filters blood plasma.
- Bowman’s capsule: Collects the filtrate.
- Proximal tubule: Reabsorbs nutrients, ions, and water.
- Loop of Henle: Establishes a concentration gradient for water reabsorption.
- Distal tubule: Further ion and water regulation.
- Collecting duct: Final site for water and solute reabsorption before urine exits the kidney
How does the glomerulus contribute to the filtration process in the kidney?
The glomerulus is a network of capillaries that filters blood under pressure. It allows water, ions, glucose, and waste to pass into the Bowman’s capsule while preventing large proteins and blood cells from being filtered
What is the primary role of the Loop of Henle in urine concentration?
The Loop of Henle creates a concentration gradient in the medulla, allowing for water reabsorption. The descending limb is permeable to water but not solutes, while the ascending limb actively transports Na+ and Cl- out, making the surrounding medulla hypertonic, which helps concentrate urine
Explain how antidiuretic hormone (ADH) affects water balance in the body.
ADH increases water permeability in the collecting duct by stimulating aquaporin channels, allowing more water to be reabsorbed into the bloodstream. This reduces urine volume and helps retain water, especially in cases of dehydration
Why do desert animals tend to have longer Loops of Henle compared to animals living in wetter environments?
Desert animals have longer Loops of Henle to maximize water reabsorption by creating a steeper osmotic gradient in the medulla. This allows them to produce highly concentrated urine and minimize water loss.
What is countercurrent multiplication, and why is it important in the kidney?
Countercurrent multiplication is the process by which the Loop of Henle creates a concentration gradient in the kidney medulla.
This allows for efficient water reabsorption from the collecting duct, helping to concentrate urine and maintain water balance.
Differentiate between filtration, reabsorption, and secretion in the nephron.
Filtration: Occurs in the glomerulus; blood plasma is filtered into the Bowman’s capsule.
Reabsorption: Essential nutrients, ions, and water are reabsorbed into the blood from the
renal tubules.
Secretion: Unwanted substances (e.g., hydrogen ions, toxins, drugs) are actively transported from the blood into the nephron for excretion
How does aldosterone regulate sodium and water balance in the kidney?
Aldosterone increases sodium reabsorption in the distal tubule and collecting duct.
Since water follows sodium osmotically, this also leads to increased water retention, higher blood volume, and increased blood pressure
Why do freshwater fish excrete dilute urine, whereas marine fish excrete concentrated urine?
Freshwater fish live in a hypotonic environment, meaning they gain water through osmosis. To maintain balance, they excrete large amounts of dilute urine.
Marine fish live in a hypertonic environment and constantly lose water, so they produce concentrated urine to conserve water
What role do the peritubular capillaries play in the kidney’s function?
The peritubular capillaries surround the renal tubules and facilitate the exchange of water, nutrients, and waste between the blood and the nephron.
They help reabsorb useful substances and return them to the bloodstream while aiding in the secretion of excess ions and waste
What are the main components of the circulatory system in vertebrates?
The heart, blood, and blood vessels
How does an open circulatory system differ from a closed circulatory system?
In open systems, hemolymph bathes organs directly; in closed systems, blood is confined to vessels.
Describe the path of blood through the mammalian heart.
Blood flows: right atrium → right ventricle → lungs → left atrium → left ventricle → body
What is the role of the sinoatrial (SA) node in the heart?
The SA node generates electrical impulses that initiate each heartbeat.
How is blood pressure regulated in the human body?
Blood pressure is regulated by neural and hormonal signals, including baroreceptors and hormones like ADH.
What is the function of hemoglobin in red blood cells?
Hemoglobin binds and transports oxygen in red blood cells.
What is the difference between pulmonary and systemic circulation?
Pulmonary circulation moves blood between heart and lungs; systemic circulation moves blood between heart and the rest of the body.
Why are capillaries important for tissue function?
Capillaries allow exchange of gases, nutrients, and wastes between blood and tissues
What is the main function of the excretory system?
To remove nitrogenous waste and regulate water, ion balance, and pH
What is a nephron, and what is its role in the kidney?
The nephron is the functional unit of the kidney responsible for filtering blood and forming urine.
Describe the process of filtration in the nephron.
Filtration occurs in the glomerulus where plasma is forced into Bowman’s capsule.
What is the function of the Loop of Henle in urine formation?
It concentrates urine by creating a salt gradient that promotes water reabsorption.
How do antidiuretic hormone (ADH) and aldosterone affect kidney function?
ADH increases water reabsorption; aldosterone increases sodium reabsorption and potassium secretion.
What is the glomerular filtration rate (GFR), and why is it important?
GFR is the rate of fluid filtration in the kidneys and indicates kidney function.
What are the main differences between ammonia, urea, and uric acid as nitrogenous wastes?
Ammonia is toxic and excreted directly by aquatic animals; urea is less toxic and common in mammals; uric acid is solid and conserves water in reptiles and birds.
How does the structure of the renal tubule contribute to selective reabsorption?
Different segments have specific transport proteins that reabsorb essential solutes.
What is the role of the collecting duct in water balance?
The collecting duct adjusts water reabsorption based on hormonal signals, concentrating urine as needed.
How do the kidneys contribute to homeostasis beyond waste removal?
They regulate blood pressure, blood volume, osmolarity, and acid-base balance.
Xylem vs. Phloem:
- two vital vascular tissues in plants
Xylem: carry water and minerals from roots to rest of plant
Phloem: carries sugars and compounds from the leaves to other parts of the plant