TXST Dr. Vargas BIO 1321.001 - Exam 3

When did plants settle on land?

~475 million years ago

- landscape drastically changed

How did plants affect the environment?

- caused CO2 to drop and O2 to rise

- paved way for animals & other heterotrophs to evolve

Plants make their own food, so they are

autotrophic

-undergoing photosynthesis

autotrophic

self-feeding

photosynthesis

process of capturing sunlight & storing it as energy in a sugar molecule

- CO2 + H2O + Sun(light) → sugars + O2

Plants exists where?

nearly everywhere

- form basis for complex food webs

- provide diverse habitats

Life on Earth...

depends on autotrophic energy; without autotrophs, all heterotrophs (i.e. humans) would die.

Plant cells

plants are multicellular

- leaf cells, flower pedal cells, root cells, etc. all carry out different functions

multicellular

made of many cells

Can plants move?

No, they are immobile.

- plants are anchored in place the base

- unable to move from one place to another on their own

plant reproduction

Most plants reproduce sexually, others asexually.

asexual reproduction (plants)

some plants make offshoots, creating identical offspring

sexual reproduction (plants)

gametes (sperm/egg) fuse together, creating an embryo

plant life cycle

alternation of generations

- multicellular diploid generation alternates with a multicellular haploid generation

diploid

2 sets of genes (chromosomes)

haploid

1 set of genes (chromosomes)

alternation of generations, pt. 1

- full plant = sporophyte (diploid): produces spores through meiosis

- spores = "pollen" (haploid): grows into a gametophyte

- gametophyte (haploid): produce gametes (sperm/egg)

- gametes (haploid): sperm fertilizes egg

alternation of generations, pt. 2

- fertilized egg = embryo (diploid): grow on gametophyte (protects and nourishes); also called seeds

- embryo (seed): develops/grows into full plant

CYCLE REPEATS

simplified alternation of generation

sporophyte → spores → gametophyte → egg/sperm → embryo → REPEAT

Primitive plants have...

obvious and distinct sporophytes & gametophytes (i.e. mosses)

More recently plants developed...

the ability to carry a gametophyte within a sporophyte (i.e. flowering plants, fruit)

flowering plants (angiosperms)

- spores/pollen released from and can land on a flower

- flower develops into fruit (i.e. cherry blossoms → cherries)

fruits

contain developing seeds

- nourish and protect the embryo/seed inside

- edible fruits are eaten: seeds pass through digestive tract unharmed

- burr fruits cling to fur

- winged fruits carried through air

ALL increase embryo/seed dispersal

Plants affect...

other organisms and the environment

- play crucial ecological/environmental role

- contribute to food, air, soil, & water

- provide shelter, fuel, medicines, & other goods

Plants provide food for...

animals, fungi, & other heterotrophic organisms

energy moves...

one way—from the sun to Earth (plants capture this energy)

organisms eat...

- plants

OR

- organisms that eat plants

to gain the energy & stay alive

plants maintain...

the atmosphere.

How do plants maintain the atmosphere?

- pull CO2 from the atmosphere

- prevent planet from getting too hot

- release O2 into atmosphere

- allow animals & other organisms to breathe

Plants build & maintain...

the soil

- dead plants decompose into organic matter—adding nutrients & making soil fertile

- roots hold soil together—preventing wind & water erosion

erosion

processes by which rock, sand, and soil are broken down and carried away (i.e. weathering, glaciation)

erosion leads to...

poor growing conditions & sometimes barren land

- more common with deforestation

What do plants keep circulating in ecosystems?

water

- absorb & store water from soil

- slowly release water into surrounding environment

- prevents immediate evaporation (causes severe water loss & drought)

- slows rate & amount of runoff/flooding

Where do many organisms live?

diverse ecosystems of plants

What important medicines do plants provide?

- taxol: important cancer drug (comes from yew trees)

- aspirin: used for fever, inflammation, etc. (comes from willow trees)

Plants provide materials for fuel and commercial goods such as...

fuel, twin, canvas, clothing, pigments, alcohol, cleaners, oils, cosmetics, etc.

major groups of plants

- non-vascular plants (about 20,000 species): 475 million years ago

- vascular seedless plants (about 12,000 species): 320 million years ago

- gymnosperms (about 1,000 species): 125 million years ago

- angiosperms (about 250,000 species): 125 million years ago

1st big evolutionary split

nonvascular v. vascular

- 1st plants were nonvascular

nonvascular plants

- no way to conduct water or nutrients around plant

- relies on slow diffusion to distribute water/nutrients

- small in size

- live in moist environments

- no eggs: sperm & egg meet in water

- must remain moist: reproduce in water

-straddle b/t aquatic & terrestrial life

- some still exist

vascular plants

- have tube shaped conducting cells (like blood vessels): provide support; transport water/nutrients throughout plant

- larger in size

- moved away from the water a bit

2nd big evolutionary split

vascular seedless v. seeded plants

vascular seedless plants

- no seeds

- require sperm & egg to meet in water

- those away from water time reproduction with heavy rains

vascular seeded plants

aided by 2 adaptations: pollen & seeds

- sperm & egg fuse to make an embryo (seed)

seeds

- protect the embryo as it grows

- provide it with nourishment

- come in many shapes and sizes

pollen

tiny grains for reproduction

- dispersed by wind or pollinators (i.e. birds, insects)

- eliminates need for sperm to swim to egg → reproduction on dry land

3rd big evolutionary split

gymnosperms v. angiosperms

gymnosperms

vascular seeded plants without flowers or fruits

- i.e. cycads, ginkgo, pine (seeds like pinecones)

angiosperms

vascular seeded plants with flowers & fruits

- most diverse & widespread of all plants

- we see most of this outside

flowers

reproductive structures in which gametophytes are formed

- evolution exploded when gymnosperms formed association with pollinators (coevolution)

- animals eat protein-rich pollen

- use animals as pollinators (increase reproduction & gene flow)

animal cells

multicellular

- blood cells, skin cells, muscle cells, etc. all carry out different functions

Can animals move?

Yes, they are motile

- all can move at some point tin the life cycle

- some are stationary as adults (i.e. barnacles, sponges), but motile as juveniles

What do animals eat?

animals are heterotrophic (the eat living organisms)

heterotrophic

Organisms that obtain their nutrients or food from consuming other organisms.

How do animals reproduce?

sexual reproduction (few exceptions)

- gametes (sperm/egg) fuse together to make new, genetically diverse offspring

Do animals have cell walls?

no, animal cells take more variable shapes bc no cell wall

- there are over 200 different types of cells in humans

branches in evolution

- has tissues?

- bilateral or radial symmetry?

- if bilateral, does it develop front-to-back or back-to-front?

- if front-to-back, does it continuously grow or grow by molting?

tissues

groups of similar cells with a specific function (i.e. muscle, bone)

sponges

the only modern animals that lack tissues

radial symmetry

can be divided into equal halves by any plane through the center

- most abundant radial phyla: Cnidarians

Cnidarians

jellyfish, coral, sea anemones

bilateral symmetry

can be divided into mirror-image halves only along one plane down the midline

- matching left & right halves

- any animal with a head

protostomes

animals that develop front to back

- "mouth first"

- mouth arises from 1st embryonic opening

- 2nd opening: anus

dueterostomes

animals that develop back to front

- "mouth second"

- Chordates

Chordates

dueterostomes

- only phylum with vertebrates

- includes mammals, birds, reptiles, amphibians, and fish

- contains humans and many animals we eat, keep as pets, and observe

- 4 distinct structures

molting

shedding of the exoskeleton (hard outer layer) to replace it with a bigger one

arthropods

largest molting phylum

- insects, crabs, lobsters, spiders, ticks, and millipedes

protostomes that don't molt...

can be soft (i.e. octopus) or have exoskeletons

- grow continuously

mollusks

largest continuously-growing protostome phylum

- includes octopi, oysters, scallop, snails, & slugs

invertebrates

96% of all discovered animal species

- insects, crab, snails, clams, octopi, starfish, worms, etc.

- contained in ever animal phylum

vertebrates

only exist in one phylum (animals with a backbone)

- chordates

invertebrates affect organisms & the environment

- play crucial roles within ecosystems, provide food, act as pollinators & decomposers

- can be parasitic, poisonous, cause illness, & spread disease

invertebrates provide...

food for many other animas (& plants)

some invertebrates act as...

decomposers

- important for recycling minerals, nutrients, & energy

some invertebrates are used in...

- leeches used in surgery to remove excess blood & promote blood flow

- blowfly maggots can rid wounds of dead tissue that interferes with healing

- "Eribulin" a chemical drug derived from sponges is used to treat breast cancer

some invertebrates are... pt. 1

parasites

- hookworm larvae bore into human feet and travel to intestine, causing continuous bleeding

- trichinella worms infect people who eat improperly cooked infected pork; larvae invade blood vessels & muscles, causing bleeding & muscle damage

- heart worms transmitted by infected mosquitos to cats & dogs

some invertebrates are... pt. 2

- tapeworms can infect people who eat improperly cooked beef, pork, or fish that has been infected by the worms (attach themselves to intestinal lining & can grow to 20 ft long or more; release eggs that shed in feces, continuing cycle)

some invertebrates spread...

disease

- ticks can spread lyme disease (causes fever, fatigue, flu-like symptoms, can lead to chronic/severe problems)

- mosquitoes can spread malaria (causes fever, fatigue, vomiting, headaches, can even lead to seizures, coma, & death)

Can invertebrates are poisonous?

yes

- some arachnids, such as spiders, scorpions, inject paralyzing venom

- some insects, scorpions, & ants can sting/bite (especially dangerous to those with allergies)

4 distinct structures of chordates

- notochord, nerve chord, gill slits, and a tail (in some, may only appear at the embryonic level)

lancelets & tunicates

invertebrates with only the basic chordate characteristics

- no skulls, backbones, or jaws, etc.

- both marine animals

1st major chordate adaptation

skull

- advantage: protects brain

- hagfish: currently living animals with a skull but no backbone (invertebrates)

2nd major chordate adaptation

backbone

- advantage: expands range of motion

- lampreys: currently living animals with a backbone but no other adaptations

3rd major chordate adaptation

jaws

- advantage: increased feeding options

- cartilaginous fish: currently living group with jaws and cartilage but no bones or limbs

4th major chordate adaptation

bones

- advantage: stronger, less brittle than cartilage

- allowed for bigger, stronger animals: support weight better

- bony fish: currently living group with bones but no limbs or lungs (fish, seahorses, eels, etc.)

5th major chordate adaptation

limbs & early lungs

- advantages: allow for movement on land

- allowed for land-time: food was abundant, escape from aquatic predators (amphibians)

amphibians

have limbs and decent lungs

- includes frogs, toads, and salamanders

- amphibian is Greek for "double life"

- begin life adapted to water & mature into semi terrestrial adults with lungs

- adults respire through lungs and moist skin

- confined to moist, watery environments

6th major chordate adaptation

good lungs & waterproof eggs

- advantage: both allow animals to live fully on land

- waterproof eggs require internal fertilization

- once egg is fertilized, waterproof shell formed, encasing embryo to prevent drying

internal fertilization

maled deposits sperm into the female's body

1st organisms to live their lives fully on land

reptiles (exothermic)

- includes lizards, snakes, alligators, turtles, crocodiles, & birds

- good lungs

- waterproof eggs

- have tough, scaly skin to protect body (prevents water loss)

birds

distinctive group of reptiles

- have feathers: highly specialized reptilian body scales

- retain scales on their legs

most birds can...

fly

- feathers provide lift & control as well as insulation

- hollow bones reduce weight of skeleton

- birds are warm-blooded (endothermic)

endothermic

warm-bloded

exothermic

cold-blooded

7th major chordate adaptation

hair & mammary glands

- advantage: hair protects & insulates

- mammary glands produce milk that nourishes young

mammals

vertebrates with mammary glands

- subdivided into 3 groups: monotremes, marsupials, placental mammals

monotremes

egg-laying mammals

- newly hatched young are nourished with milk from mammary glands

- includes few species: the platypus & a few spiny anteaters (echidnas)

- found in Australia & New Guinea

marsupials

common in Australia

- include opossums, koalas, kangaroos, wallabies, wombats, & the Tasmanian devil

- embryos begin development inside a uterus

- young are born prematurely: crawl to a nipple to complete development

- post-birth development completed in protective pouch

placental mammals

1st mammals evolved on land (some moved back to water: whales, otters, dolphins)

- inhabit land, air, and sea

- highly divers: includes bats, moles, whales, monkeys, cheetahs, seals, humans, etc.

Most mammal species are...

placental mammals

- uterus contains a placenta that provides gas, nutrient, & waste exchange b/t parent and embryo

- young are retained in uterus for entire embryonic development

~20% of mammalian species

bats

- only mammals to have evolved wings & flight

- over 1,000 different species