EXAM 2

Plants ❤

Plants ❤

• eukaryotic, multicellular photoautotrophs

• cellulose in cell walls

• chlorophylls A and B in chloroplast

• sporopollenin coating around cells → prevents drying out

• Embryophytes- embryo is protected in parental tissue

• Alternation of generations

• Apical Meristems

• Walled spores found in sporangia

• LAND! ~470-475 million years ago

• cuticle (waxy layer) + pores

Embryophytes

• embryos develop in parental tissue

• parental tissue → provides nutrition and protection

Alteration of Generations

• multicellular sporophytes (2n)

• haploid spores + mitosis/cell divison → multicellular gametophyte (n)

• haploid gametes make a diploid zygote

Apical Meristems (stem cells)

• cells that can continually divide → found at tips of shoots and roots

walled spores made in sporangia:

• cells in sporangium undergo meiosis + form haploid spores → protected by sporopollenin.

cuticle

waxy layer covering plant

• pores, to allow movement of gases in and out of cells

• in most plants, pores = stomata

major groups of plants:

• non-vascular plants

  • Bryophytes; liverworts, mosses, hornworts

• vascular plants

  • seedless plants -

    • lycophytes

    • monilophytes

  • seed plants

    • gymnosperms

    • angiosperms

Bryophytes: Liverworts, Hornworts, and Mosses

Blade = thallus

green photosynthetic organism: gametophyte generation (dominant generation)

Liverworts:

seedless vascular plants

• Seedless vascular plants

  • lycophytes

  • monilophytes

    • ferns

    • equisetum

    • whisk ferns

• sporophytes have sporangia → spores produced on modified leaves → sporophylls.

• several sporophylls together - strobilus/sorus

• due to vasculature → bigger plants!

Vascular plants

• gametophyte highly reduced → female gametophytes retain

• vasculature

  • xylem - usually from roots to top of the plant

  • phloem - transports sugars from leaves to roots

• true leaves and true roots

  • lycophytes - microphylls

  • rest of plants - megaphylls + branched vasculature and larger

gymnosperms

• conifers

• gingko

• cycads

• gnetophytes

• female cones (ovulate) → made of sporophylls → each sporophyll ovule contains mega sporangia (2n) (undergoes meiosis) → (n) megaspore → female gametophyte, contains egg cell

  • one cell = egg cell

• male cones → each sporophyll contains microsporangium -made of sporophytes → strobilus → microsporangia → 2n (undergoes meiosis) → multiple microspores(n) → multiple male gametophytes → each gametophyte = 3-4 cells large; AKA POLLEN

• male gymnosperm/angiosperm gametophyte → POLLEN

  • one cell in the pollen grain = sperm cell

• pollen grain released into the air → if it comes into contact with egg cell → sperm cell can fertilize egg cell → makes 2n zygote → makes 2n embryo; surrounded by other food and hard covering, makes the seed

heterospory

spores with different sizes

(ex. female gymnosperm cones are huge, male gymnosperm cones are tiny)

Angiosperms - flower reproduction

• basal angiosperms

  • basal organism - earliest diverging group in a clade

• magnoliids + monocots → parallel veins, lcotyledon, scattered vascular tissue, leaves, fibrous root, flower puts in multiples of 3

• eudicots - net-like veins in leaves, 2 cotyledon, ringed vascular taproot, flowers parts in 4-5 species, tissue

clade

common ancestor and all descendants

stamen

male reproductive structure in angiosperms

• stamen → anther → microsporangium

• makes microspores → male gametophyte; pollen grain → has sperm cell

• pollen grain eventually makes way to carpel (pistil) → fertilization of sperm cell with egg cell → 2n zygote → embryo + surrounding food reserves + hard protective coat → SEED surrounded by fruit

animals are known as

metazoa

Animals:

• sexually reproduce → diploid dominant

• multicellular

• eukaryotic

• chemoheterotrophs

• ingest food

• has larval stage → sexually immature stage with morphological differences from the adult

• life cycle: n → 2n zygote → diploid multicellular → cycle repeates.

other animal characteristics

True tissues -

Tissues - group of connected cells with common function

ex. muscle, nervous system → movement and capture of prey

• digestive system

• unique embryonic development

  • 2n zygote undergoes cleavage → fertilized egg divides into many cells without growing.

  • end result of clevage → formation of blastula

  • blastula undergoes gastrulation → forms gastrula. cells grow into the hollowness of blastula → forms blastocoel

  • forms 2 layers of cells:

    • ectoderm → outer layer

    • endoderm → inner layer

  • Metazoa → monophyletic group → have one shared common ancestor

blastula

hollow ball of cells

sister group to metazoans

choanoflagellates

Evidence:

• DNA and biochemical evidence

Ponifera

basal animals

• some cells = choanocytes

• other specialized cells within → beginnings of multicellularity → cadherin attachment proteins containing “CCD” domain, only found in animals

Animals evolved during the

Neo-Proterozoic era

650 MYA → 541 MYA

• Biochemical evidence, molecular fossils

• Molecular biology and understanding of mutation rates

Eumetazoans - Cnetophres + Cnidaria

• Basal Eumetazoans - Ctenophores + Cnidaria

• Radial symmetry - particular set of morphologoical developmental traits in a group of organisms

Body plan:

• radial symmetry

• central cavity = gastrovascular cavity

• Dipoblastic Development - all tissue of animal develop from two embryonic layers: ectoderm+ endoderm

Complex Body plans:

• due to apperance of hox genes → cell signaling, organism development

Eumetazoans - Bilateria

• Bilateria → dominant form of animals

• rise in diversity/abundance → Paleozoic ~451 MYA, starting with Cambrian Explosion. Why?

  • new predator/prey relationships

  • increase in oxygen

  • evolution of new hox genes

• Bilaterally Symmetrical - can bisect organism only in one direction

• anterior - head of the organism

• posterior - rear end of the organism

• dorsal - the spine/back of animal

• ventral - the tummy/front of animal

alimentary canal (bilateria)

complete digrestive tract

Cephalization (bilateria)

• sensory organisms (+ integration of information) at anterior end of the organism

Tripoblastic Development (bilateria)

• ectoderm, mesoderm, endoderm

Acoelmate (bilateria)

no extra body cavity

Coelmate (bilateria)

• extra body cavity inside mesoderm → coelom

Hemocoel (bilateria)

body cavity in mesoderm + endoderm

*pseudocolem/ pesudocoelmate

(bilateria) Acoela

• Acoelomates

• Basal Bilaterians

• relatively small (worms)

• marine organisms

3 major clades of Bilateria

• Deuterostomia

• Lophotrochozoa

• Ecdysozoa

Deuterostomia (bilateria)

• Echinodermata

• Hemichordata

• Chordata (us)

• Deuterostomic embryonic development

blastospore

pore formed when endoderm grows into the blastocoel during gastrulation

Deuterostomic embryonic development vs. Protostomic Development (found in some lophotrochozoans + ecdysozoans) (bilateria)

1. cleavage

   • Protostome: spiral and determinate

   • Deuterostomes: radial + indeterminate (to 8-cell stage)

2. Coelom formation - mesoderm

   • protostome: split of mesoderm to form cavity

   • deuterostome: mesoderm from folds of endoderm → coelom comes from archenteron

3. fate of the blastopore

   • protostome - blastopore becomes mouth

   • deuterostome - blastopore becomes anus, mouth forms later on

Ecdysozoa (bilateria)

• most abundant + diverse of animals, due to Arthropoda phylum

• molting animals - shed exterior skin/skeleton while they grow

Lophotrochozoa (bilateria)

• categorized by DNA evidence

• SOME lophotrochozoan; lophophore - feeding structure

• SOME have; trochopore larva stage

Paleozoic ~541-250 million years ago

• increase in diveristy + abundance of bilaterians

• 465 million years ago → animals move onto land

Paleozoic to Mezozoic → mass extinction. 96% marine species, 77% terrestrial species gone/

increase in CO2, H2S, methane → rapid climate change → rapid extinction

Mesozoic ~250MYA to 66MYA

• rise of reptiles

• more movement onto land

• beginning of coral reefs

• first mammals

**Cenozoic 66MYA - present

• cooling of global climate

• rise of the mammmals

Summary of animals

1. all animals share a common ancestor

2. Porifera (sponges) are basal animals

3. Eumetazoa is a clade of animals with true tissues

4. Most animals belong in the Bilateria

5. The three major clades of Bilaterians are

   1. Deuterostomia (us)

   2. Lophotrocozoa

   3. Ecdyzodoa (known for molting)

Anatomy

structures of an organism

Morphology

overall form and structure

Physiology

function

Animals are

multicellular chemoheterotrophs that ingest food

Direct Exchange

all cells able to exchange directly with the environment

• ex. Porifera, Basal Eumetazoans

Cnidarians

• directly through outside environment

• or through gastrovascular cavity

Most animals: Indirect/Internal Exchange

• requires transport of substances (molecules + compounds) to and from outside to every single cell

Multicellularity allows for

division of labor - through organ systems

organ systems

set of structures with a common function

ex. digestive, respiratory system, circulatory system, excretory system, reproductive, Integumentary (skin), skeletal, muscle

organs are

structures made of tissues with a specific function

*made up of tissues

tissues

a group of integrated cells w/ common function and/or structure

• epithelial tissue - cells found on the surface of outer or inner organs

• Connective tissue - cells that connect different tissues/ parts of body (connects epithelium to muscle)

• Nervous Tissue

• Muscle Tissue

Connective tissue

cells that connect different tissues/parts of body (connects epithelium to muscle)

• In general, cells secrete and have large extracellular matrices

• Fibrous connective tissue vs.

• Loose connective tissue

  • cushioning, lubrication, flexability

• Specialized connective tissue - blood, cartilage, bone, adipose

Nervous Tissue

• Neurons - process and transmit information

• Glia - support cells of nervous system

Muscle Tissue

• skeletal muscle

  • voluntary movement

• cardiac muscle

  • heart

• smooth muscle

  • involuntary movement found within ogans

Epithelian tissue categorized based on;

Shape

• columnar - long, cuboidal - square, squamous - squished up

Number of Layers

• 1 layer = simple pseudostratified

• multi-layer = stratified

Homeostasis

physiological steady-state of the body

Coordination + Control

• organisms working together → organism

• being able to interact with environment → response to environment

• maintenance of HOMEOSTASIS - physiological steady-state

• homeostasis = regulation

* Two primary organ systems involved in coordination + control

• Nervous system

• Endocrine system

1. stimulus percieved

2. signal sent to other parts of body

3. signal is recieved and interpreted

4. response

Nervous System

1. sensory neurons

2. nerve impulse (signal)

3. signal sent to center of integration; interneurons (ex. brain, spinal cord)

4. Nerve impulse through motor neurons

5. Leads to movement, or glandular release

• nervous system = fast, one -time, short term

Endocrine System

1. Stimulus is perceived by endocrine gland (ex. pancreas, adrenal gland)

2. signal = hormone; sent through circulatory sytem

3. Signal recieved by cells containing hormone receptors

4. signal transduction cascade → leads to movement, metabolism changing, or gene expression

• Endocrine system = slower, long lasting

Basic responses to cell signaling

1. altered cell shape or movement

2. altered metabolism

3. altered gene expression

In humans → physical+ chemical properties maintained

• blood sugar

• body temperature

• blood pressure

• tonicity (salt content in body)

• O2 levels, RBC

• blood pH

Regulators

• able to alter internal conditions to maintain a particular homeostatic parameter

Conformer

• animal whose physiological state highly influenced by external environment.

how is homeostasis maintained? Mostly Negative Feedback

• when the end product of a process is perceived and used to inhibit or counteract the process

• example: blood clotting

• initial formation: positive feedbak

• to end blood clot and prevent it from getting too big - negative feedback

  1. blood vessel wall tears, feedback cycle initiated.

  2. clotting occurs and platelets adhere to site and release chemicals.

  3. chemicals released attract more platlets, cycle repeats

  4. clotting done 😽

Positive feedback

• end product of process speeds up process

Changing homeostasis

ex. circadian rhythm:

• body temperature, body pressure, heart rate

• includes acclimatization - gradual process by which an animal adjusts to its external environment

  • ex. living in high altitude; your body adjusts to the low amount of oxygen

Thermoregulation

• process by which an animal maintains body temperature (within a reasonable range)

• Homeotherm vs. Poikilotherm

Homeotherm

maintains a relatively stable body temperature (Temperature regulator

Poikilotherm

animal whose body temperature fluctuates with external environment (temperature conformer)

Endotherm

animal that generates its own heat

Ectotherm

gain heat from external environment

Heat transfer in animals

• transfer of thermal energy from one object to another

• evaporation - loss of heat from molecules going from liquid to gaseous state

• convection - transfer of heat due to movement of air or liquid over a surface

• conduction - heat exchange between molecules of surfaces that are in direct contact

• radiation - heat exchange due to emission of electromagnetic wavelengths

Methods of Thermoregulation

• Insulation - (mostly to stay warm)

  • layers of fat, Blubber

  • oily feather/fur

  • Raising of feathers/fur (fluffed up feathers) - creates layer of air that insulates between the body and the outside

• Countercurrent exchange - (to stay warm)

  • arteries (blood vessels coming from the heart→ blood moves from inside to outside) with warmer blood next to veins (blood vessels returning blood from extremities back to heart) with cooler blood. Heat goes from arteries → veins, keeps blood at a relatively stable temperature

• To maintain body temperature in a changing environment

  • Heat is generated as a byproduct of metabolism and cellular work

  • Negative feedback

  • Hypothalamus - Thermostat in our bodies

• Thermosesnsors - sensory neurons found throughout our body that sense changes in temperature

• Thermosensors(send a nerve signal) → hypothalamus →(sends a nerve impulse_ Response

• Response to increase body temperature (external environment is COLD)

• shivering (cellular work to generate heat)

• non-shivering thermogenesis (occurs in brown fat) (increase in cellular respiration)

• vasoconstriction - narrowing of blood vessels underneath the skin, prevents heat exchange

Response to body temp increasing (due to HIGH temperature)

• vasodilation - widening of blood vessels underneath skin

  • more blood = more heat near skin → more heat loss

• evaporative cooling - sweating, panting

altering behavior

• to increase/decrease temperature

• (Ex. move to the shade when it’s too hot outside)

Caloric homeostasis

energy use + allocation

Bioenergetics

study of overall flow + transformation of energy

Metabolic rate

sum of all energy used in a given amount of time

Standard metabolic rate

metabolic rate of an ectothermic animal that is non-stressed, non-feeding at a particular temperature

Basal metabolic rate (BMR)

minimum metabolic rate of a non-growing, fasting endotherm at rest

Metabolic rate unit

measured in Kcal

When looking at per kg of mass:

• the higher the mass, the lower the BMR(basic metabolic rate) /kg of mass

Torpor

physiological state of decreased activity

Hibernation

long term torpor

Nutrition

process by which an organism obtains and uses a food substance

Nutrients

substances needed by organisms for survival

Macronutrients

nutrients needed in large amounts

ex. proteins, lipids, and carbohydrates

• needed for chemical energy

micronutrients

nutrients needed in small amounts

• vitamins - organic molecules that are needed by body in small amounts

• minerals

• required many times in functioning of certain enzymes

Essential nutrients

• nutrients that cannot be made by an organism from basic building blocks

• includes all micronutrients and some macronutrients

Non-essential nutrients

• can be synthesized by organism from basic building blocks

Nutrient deficiency

Malnutrition: when diet of an organism lacks one or more essential nutrients

Undernutrition - failure to provide adequate sources of chemical energy

Overnutrition

when more is consumed than needed

Intracellular digestion

uptake and breakdown of nutrients by individual cells

Extracellular digestion

uptake and breakdown of food outside of cells into smaller particles before uptake or absorption into cells

eg. use of gastrovascular cavity - central cavity with one opening

Alimentary canal -

complete digestive tract

• long tube with 2 openings, food enters the mouth, undigested food leaves the anus

• long tube is separated into compartments

4 stages of nutrient processing

1. Ingestion - intake of food

2. Digestion - breakdown of food into smaller particles

3. Absorption - uptake of nutrients into cells

4. Elimination - removal of undigested/unabsorbed waste from the body

Ingestion Feeding Mechanisms

filter feeding - food strained from liquid medium

substrate feeding - when organism lives in or on food source

fluid feeding - sucking nutrient-rich fluid from host organism

bulk feeding - when food particles are taken in bulk