Biodiversity FINAL

Alteration of generations

Alteration of generations

2 multicellular life stages

What is a sporophyte?

a spore plant whose spores grow into Gametophytes

What is a gametophyte?

a gamete plant, gametes fuse and grow into a sporophyte

What do sporophytes produce?

spores

What do gametophytes produce?

gametes, most can produce male and female (sperm and egg) but some plants can only produce one (male OR female)

What is an example of a gametophyte?

moss

multicellular plant life stages

1. sporophyte- produces spores
2. spores grow into gametophytes
3. gametophytes produce gametes
4. gametes fuse and divide into sporophyte

What was the ancestor of green plants?

Charophycean Algae

Describe Charophycean Algae

· believed to be ancestor because they’re morphologically similar to green plants (anatomically)

· has similar cell structure to green plants

· physiologically similar to green pants (metabolic processes)

· could perform photosynthesis,

· genetically similar to green plants (chloroplasts, DNA)

Do green plants and Charophycean Algae probably share a common ancestor?

yes

How did plants move from water to land?

The ancestor of plants (a SINGLE CELLED aquatic algae) was stranded on land through the splash hypothesis OR the dry pond bed hypothesis, and it was favored by selection if it could live

Describe the splash hypothesis

the single celled ancestor of plants SPLASHED up on land for less than or around 12 hours (probably from tides)

Describe the dry pond bed hypothesis

the single celled ancestor of plants was stranded during the dry season when the pond dried up. Stranded for about 2-6 WEEKS

What evidence is there that Charophycean algae is (maybe) green plants’ ancestor?

they both have a protein in their cell wall that is unique to only green plants and Charophycean algae

What is sporopollenin?

A protein in the cell wall of green plants and Charophycean algae that PREVENTS DRYING OUT

What is desiccation?

Drying out

Why would plants’ move to dry land be favored by selection?

1) Better access to sunlight

2) Better access to nutrients (the ground is a bed of nutrients)

3) better access to CO2 gas (in water, CO2 diffused into the water and turned into carbonic acid which meant plants had to take extra steps to get CO2 from the water aka: easier to get CO2 on land)

4) NO predators (only briefly)

What were the special adaptations for terrestrial life?

1) Waxy cuticle

2)  Stomata

3) Roots and Shoots

What does a waxy cuticle do?

prevents water loss

What are Stomata?

pores that allow gas exchange to occur. Can be opened or closed

What are roots and shoots?

· region of rapid cell division

·  SHOOTS: allow for competition for sunlight.

ROOTS: allow for competition for water and nutrients

What are the four major plant groups?

Bryophytes, Monilophytes, Spermatopsida, Gymnosperms and Angiosperms

Describe Bryophytes

• non-vascular plants, ex: moss

  • relies on diffusion for water and nutrients to get to every cell

  • no true leaves or roots

    • limited in height

  • gametophyte dominant - sporophyte grows off gametophyte for water & nutrients

  • flagellated sperm: must “swim” through water to contact egg - water-dependent reproduction

    • restricted to damp ecosystems

How do sporophytes and gametophytes behave in Bryophytes?

· sporophyte grows OUT OF gametophyte like a branch

· DEPENDENT ON GAMETOPHYTE for H2O and NUTRIENTS (gametophyte is dominant)

· water is REQUIRED for SPERM to SWIM to EGG (flagellated sperm)

·  restricted to DAMP HUMID CLIMATES

Describe Monilophytes

• seedless vascular plants, ex: first giant ferns

  • vascular system

  • true leaves & roots

    • can grow tall

  • sporophyte (large & complex) and gametophyte (small & dime-sized) are independent of each other; they’re 2 distinct plants

  • water-dependent reproduction

    • restricted to damp ecosystem

How do sporophytes and gametophytes behave in Monilophytes?

· Sporophyte is DOMINANT

·  sporophytes and gametophytes are INDEPENDENT of each other (they're two distinct plants)

· Gametophyte is TEMPORARY

· H2O is NEEDED for sperm to swim to egg (confined to damp, humid climates)

Describe Spermatopsida

seed bearing vascular plants

• two groups: gymnosperm & angiosperm

• vascular system has lignified walls

  • plants grow tall

  • true leaves & roots

• sporophyte dominant - gametophyte microscopic and relies on the sporophyte

• male gametophyte in pollen grains

  • no longer water-resistant reproduction

  • no longer restricted to damp environments

How do sporophytes and gametophytes behave in Spermatopsida?

· SPOROPHYTE is DOMINANT

· gametophyte is microscopic and DEPENDENT on sporophyte

· Female gametophyte is retained by sporophyte

·  the male gametophyte is released in a POLLEN GRAIN

· reproduction is NOT dependent on H2O

· the fertilized egg becomes a seed

· NOT restricted to a damp climate (gymnosperms and angiosperms)

Describe Gymnosperms

• cone-bearing, ex: pine-trees

  • pollination primarily dependent on wind

  • male gametophyte in male cone (small & yellow)

  • female cone (large & brown)

    • each blade carries two female gametophytes (microscopic)

  • gym means “naked” and sperm means “seed”, gymnosperms = naked seed with wing for dispersal

Describe Angiosperms

• flower-bearing, ex: flower

  • male gametophyte in the anther

  • female gametophyte in the carpel

  • pollination is primarily dependent on animals

  • ovary develops into fruit: a seed dispersal mechanism

What is fruit?

a seed dispersal mechanism

What is a seed?

a sporophyte embryo packaged with a food supply

Example of Bryophyte

moss

Example of Monilophytes

ferns

When you look out at an Oak Tree (which is flower-bearing), you are seeing …

a sporophyte

Which structure is dominant in moss?

a gametophyte

The sporophyte is the plant structure that…

Produces spores

How do non-vascular plants transport water and nutrients to all their cells?

They rely on simple diffusion of water and nutrients from the soil into all the cells.

What benefits does the plant get from a waxy cuticle?

The ability to reduce water loss.

What benefit does the plant get from sperm encapsulated into pollen grains?

The ability to expand into dry climates

What is a seed?

A sporophyte embryo packaged with a food supply

What is a fruit?

A seed dispersal mechanism

Which group was the earliest terrestrial plant on the earth (at least that we know of at this time)?

Bryophytes

Which group relies the most heavily on wind as a pollinator?

Gymnosperms

Which group is vascular, but non-seed-bearing?

Monilophytes (ferns)

In which group is the sporophyte completely dependent on the gametophyte?

Bryophytes

What is significant about the Monilophytes (ferns)?

The sporophyte and gametophyte are independent of each other.

Characteristics of Animals

1. Chemoheterotrophic ; energy derived from organic molecules (cellular respiration) carbon derived from organic molecules (cellular respiration)

2. Motile ; can move

3.  Multicellular

Describe the ancestor of animals

most likely similar to choanoflagellates

Describe choanoflagellates

·  Single celled

·  Can live independently OR in colonies

·  Ancestor of animals (most likely)

Classification of animals levels (levels of development)

1.  Presence of Tissue

2.  Symmetry

3. Embryonic Development

4.  Growth/Development AFTER birth

What are tissues?

a group of cells that performs a common task

What does it mean to have true tissues?

It means that there are groups of cells specialized in specific tasks that benefit the entire organism.

When did all the animal phyla (major groups) that exist today first appear?

During the Cambrian Explosion

Why are sponges considered animals?

they have a motile larva stage

Which group of animals shows bilateral symmetry?

Everything except the sponges and cnidarians

In which organism does the blastopore become the mouth?

Protostome

In which organism does the blastopore become the anus?

Deuterostome

What is the hole that becomes the mouth or anus called?

Blastopore

In which organism does the “second hole” become the mouth?

Chordates

What does it mean to have radial symmetry?

It means that any plane through the mid-point will divide the organism into mirror image halves.

Which group of animals shows radial symmetry?

Cnidarians (jellyfish)

What does it mean when cells are indeterminate?

it means if you isolate one, it’ll grow into a complete organism

What was the first type of animal to have a skeleton made of bone?

fish

In what era did the Amniotes arise?

Paleozoic

What is the idea of specialization of labor?

· benefits the entire organism

·  no individual cell has to perform ALL tasks necessary for survival

Do sponges have true tissues?

no

Describe the inside cavity of a sponge

·  lined with choanoflagellate

·  each choanoflagellate feeds itself

· extra nutrients diffuse over to the epidermal cells

What’s the exterior of a sponge lined with?

epidermal cells

What organism does symmetry not apply to?

sponges

What is symmetry?

dividing an organism into mirror-image halves through the midpoint

What is bilateral symmetry?

you can only put a plane ONE place and divide the organism into 2 mirror image halves

Describe the “polyp” stage of the jellyfish life cycle

the adult form of a jellyfish, reproduce A-SEXUALLY, NOT motile

How do polyps reproduce?

they either grow polyps that break off or they develop a reproductive structure that produce Medusa

Describe the Medusa (aka Juvenile) stage of a jellyfish life cycle

reproduce SEXUALLY, produce planulae, planulae are separated and sink due to ocean currents and turn into polyps

Describe Planulae

NOT reproductive but DISPERSIVE, microscopic

jellyfish life cycle

• polyp adult → asexual - “bud” anew polyp or produce medusae (most jellyfish carry out this life cycle)

• medusa juvenile → sexually produce plantulae

• planula → dispersive, does not reproduce. sinks to the ocean floor and develop into polyp

What is the 8 cell stage?

when an embryo undergoes cell division and becomes a Protostome

Describe the cells involved in the 8 cell stage for Protostomes

cells are determinant (aka: stem cells)

What is a determinate cell?

a stem cell, it is already determined what the cell will turn into

Describe the cells involved in the 8 cell stage for Deuterostomes

they are indeterminate (aka: NOT stem cells) Each cell can divide into a complete organism (identical twins)

What does "the cells of a deuterostome are indeterminate (at the eight-cell stage)" mean?

you can isolate one and it will grow into a complete organism

Describe the 100 cell stage

· comes AFTER the 8 cell stage

· The embryo is no longer a cube, it’s a hollow ball

What is the first thing to form during the 100 cell stage?

the blastopore (becomes one end of the digestive tract)

Give examples of protostomes and deuterostomes

Deuterostomes: starfish (echitoderms) and chordates, Protostomes: everything else DOES NOT APPLY TO SPONGES AND JELLYFISH

Describe development after birth

increasing # of cells in organism (its getting bigger)

What are adders and what are examples of these orgs?

they add cells at a constant rate (mollusks, annelids (earth worms) , flatworms) aka PROTOSTOMES

What are “molters” and what are examples of these orgs?

· they shed their exoskeleton

· they have periods of rapid addition of new cells (growth)

· they secrete a new exoskeleton

·  they have long periods of stasis (no growth) followed by a period of rapid growth

crabs, bugs, spiders, millipedes, nematodes aka PROTOSTOMES

What are the four characteristics of chordates?

1.  Dorsal Hollow Nerve Chord

2. Notochord

3. Pharyngeal Slits

4. Post Anal Tails

Describe Dorsal Hollow Nerve Chord

main nerve chords goes down back

Describe Notochord

·  supports the nerve chord

·  also dorsal

· NOT present in insects/invertebrates

Describe Pharyngeal Slits

also called GILLS (fish, salamanders), humans have gills during embryonic development

Describe Post Anal Tails

(muscular) notochord extend beyond the anus (tailbone, coccyx)

What is “Pikaia” ?

The earliest known chordate

What could be the ancestor of the chordates and why?

· Tunicates

· Adult form could have become obsolete, and the larva (juvenile form) became the ancestor of the chordates

Describe Tunicate larvae

has all 4 characteristics of chordates, therefore: Tunicates are a nice combo of invertebrate and chordate characteristics

What are the levels of classification for chordates?

1. Presence of brain

2. Presence of cranium and cephalization

3. Presence of a vertebral column

4. A lot of things happen at once

5.  Lungs

6.  Lobed Fin

7.  Legs

8.   Amniotic Egg

9.  Mammary Gland

Presence of brain (level 1)

·  Tunicate adults don’t have brains, but their larva do

·  Lancelet may serve as model for evolution of the brain

Describe Lancelets

slight enlargement at one end of the nerve chord which may or may not have been a brain

Presence of Cranium and Cephalization (level 2)

· Hagfish: loosely woven cartilaginous basket that surrounds the brain that MAY serve as the MODEL for the evolution of the cranium

· Cephalization: aggregation of the major sense organs (eyes, whiskers, etc) on the front (anterior) of the body (head)