BSC 121 Exam #2 (Shakirov)

haploid: meiosis; gametophyte (n)

diploid: fertilization; sporophyte (2n)

What is the alternation of generations in a plant’s life cycle

cuticle and sporopollenin (thick spore wall) to remove moisture

stomata to facilitate gas exchange and regulate water loss

symbiotic relationship with fungi to obtain nutrients from soil

distinctive features of land plants and their adaptations developed to live in drier environments

cuticle

waxy surface coating that helps reduce water loss from plant surfaces

embryophytes

land plants that appeared 450 mya; sporophyte has a resting stage when it forms

apical meristems

differentiated tissues that arise from one or more actively dividing cells at the growing tips

sporophyte

a diploid zygote divides by mitosis to produce a ________

spores

tough-walled, non-flagellate cells; produced when a mature sporophyte undergoes meiosis

1. populations of haploid cells grow by repeated mitotic division

2. Cells are stimulated into developing into gametes (both + and - are released)

3. mating occurs between gametes of opposite types

4. a diploid dormant zygote forms and develops a tough wall

5. the zygote divides by meiosis, yielding 4 haploid cells

Explain the life cycle of a zygote.

bryophytes

have a waxy cuticle and pores or stomata but lack tracheids; do not have vascular tissue; liverworts, mosses, and hornworts

tracheids

specialized cells for water transport

alternation of generations in mosses

Antheridia has numerous spermatogenous cells that develop into sperm cells. Biflagellate so they need water to swim to the egg (located inside the archegonium).

nutrients between the sporophyte and gametophyte move along the cell walls using a placenta

attached to the gametophyte

nutritionally dependent on the gametophyte

bears a single sporangium

lacks conducting tissues

Explain the characteristics of sporophytes in mosses.

prominent generation (for most)

free living

undifferentiated

Rhizoids

Explain the characteristics of gametophytes in mosses.

there is a lack of vascular bundles, so there is no branching and only one sporangia per sporophyte

Why is the growth of moss limited?

tracheophytes

evolved 420 mya; produce internal water and nutrient conducting tissues that also provide structural supports

branched and contain conducting tissues- phloem for sugars and xylem with lignin to conduct water and provide structural support

Explain the structure of stems of vascular plants and what they do.

specialized in water and mineral uptake from the soil

Explain the function of roots of vascular plants

flattened, specialized in photosynthesis

Explain the structure and function of leaves in vascular plants.

they are the base for most ecosystems, they sustain and feed us, and we harvest many of their compounds as medicine

how are vascular plants useful?

sperm is flagellated so it needs water to swim to encounter the egg and fertilize it

dominant phase is sporophyte (diploid)

vascular plants but seedless; young sporophyte is attached to the gametophyte, but eventually detaches and becomes an independent plant

Explain the alteration of generations for ferns!

dominant generation

becomes independent

roots, stems, and leaves

many sporangia

What are four characteristics of vascular plant sporophytes?

free-living

short-lived

What are two characteristics of vascular gametophytes?

spermatophytes

seed producing plants; includes gymnosperms and angiosperms

cycads, ginkgos, conifers, and gnetophytes

differentiated spores- mega and microspores

depend on the sporophyte

female gametophyte is food for sporophyte embryo

male and female cones

What are five characteristics of gymnosperms?

mega- retained in the sporangium

micro- develop as pollen grains

Explain megaspores vs microspores.

flowering plants

female gametophyte (n) enclosed in ovary (2n)

male and female gametophytes (n) are part of the flower (2n)

What are three characteristics of angiosperms?

they utilize double fertilization

1. one sperm + ovule = zygote or embryo

2. 2nd sperm + central cell (2 nuclei) = endosperm

Explain the alteration of generations in angiosperms:

provide protection and nutrition to the embryonic sporophyte

increase survival value

great advantage over plants that shed their spores

What are three characteristics of seeds?

gametophytes are formed within the sporophyte (no longer free-living)

fertilization occurs within the sporophyte

water is not necessary for fertilization anymore

Explain the alteration of generations in gymnosperms:

higher dominance of the sporophyte

gametophytes are microscopic and nutritionally dependent on the sporophyte (which is much bigger)

What happened to the sporophyte over time in gymnosperms and angiosperms?

microspores and megaspores

What are the two types of spores produced by seed plants?

microspores (pollen)

produced by microsporangia; contain the male gametes

megaspores (ovule)

produced by megasporangia; enclosed in sporophytic tissue called integument; each one contains only one egg

seeds contain female gametophyte tissue rich in carbohydrates, proteins, and lipids

single fertilization (sperm + egg = embryo)

What are two characteristics of a gymnosperm ovule:

double fertilization (sperm 1 + egg = embryo, sperm 2 + 2 polar nuclei = endosperm)

female gametophyte only has 7 cells

What are two characteristics of an angiosperm ovule:

seed coats protect seeds and are adapted for dispersion in many ways

seeds store a lot of food which helps the embryo develop and germinate

fertilization is not dependent on water; pollen tubes deliver the sperm directly into the ovule

What are the three advantages of producing seeds?

development of soils increased fertility

rise of oxygen levels in the atmosphere reduced CO2 levels and increase O2 levels

evolution of modern plant communities

colonization of land by animals because of greater O2 levels

rise of seed plants contributed to diversification of insects

How have land plants changed the earth? (5 ways)

seedless vascular plants

gymnosperms and angiosperms evolved from _____ _______ _______

wood, paper, food industry, cosmetics, and medicines

What are gymnosperms and angiosperms used for? (5 things)

vascular cambium

makes wood and inner bark with secondary growth

pollen

allows for the dispersal of male gametophyte

ovules

protect and nourish female gametophytes and developing embryos

seeds

facilitates dispersal

secondary xylem, produced by a second meristem called cambium

pipe-like arrays of empty, water conducting cells with lignin walls

What are two characteristics of wood?

lignin walls

provides physical and structural support

bark

produced by a cork cambium to prevent the epidermis splitting when the vascular tissues expand

primary growth

pith, phloem, xylem, and sclerenchyma

secondary growth

pith, primary and secondary phloem, cork, bark, cortex, epidermis, vascular and cork cambium, and primary and secondary xylem

true! up to a year can pass from pollination to fertilization, and seed maturation might take 3 years

true/false: gymnosperms are slow to reproduce

false! they grow throughout most of the world, and they are the dominant vegetation in many colder and arctic regions

true/false: gymnosperms grow in very few areas of the world

earliest diverging lineage of gymnosperms

palm like; not usually very tall

many produce coralloid roots

plants produce either female or male cone-like structures

insects are the main agents of pollination

seeds are dispersed by birds, bats, etc.

What are 6 characteristics of cycads?

cycads

seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves

conifers life cycle (picture)

seeds (NOT fruits) can be dispersed by wind or by animals

their wood contains specialized tracheids that makes water movement efficient and valves that prevent air bubbles

have resin to prevent attacks from pathogens and herbivors

What are three characteristics of conifers?

conical shape helps them shed snow

leaf shape and structure resists damage from drought

scale-like or needle-like leaves reduce area to decrease evaporation

thick, waxy cuticle in leaves reduces water loss and attack of insects

How have conifers adapted to colder weather?

gnetum, ephedra, and welwitschia mirabilis

What are the three types of gnetales?

gnetum

broad leaves; 30 spp. of vines, shrubs, or trees in tropical africa or asia

ephedra

scale-like leaves, whorled, photosynthetic branches; 35 spp. around the world

welwitschia mirabilis

strange looking plant, long taproot, stubby stem barely visible, only 2 leaves that grow continuously and shred; 1 sp. restricted to the Namib Desert in SE Africa

flowers: foster seed production

fruits: favor seed dispersal

endosperm: provides food for the embryo to develop

vessels: water conducting cells (wider than tracheids)

What are four key innovation of angiosperms?

flowers

produced at stem tips, contain sepals, petals, pollen-producing stamens, and ovule-producing carpels; # of organs varies greatly

when it lacks one of the four key organs

what makes a flower an incomplete flower?

facilitate pollination

everything in the flower is designed to:

organs of a flower (picture)

stamen (anther + filament), pistil (stigma + style + ovary), perianth (petal + sepal), ovules, receptacle, and pedicel

life cycle of angiosperms (picture)

secondary metabolites

organic compounds not essential for cell structure or growth, but aid in survival and reproduction

terpenes and terpenoids, phenolic compounds, and alkaloids

What are 3 types of secondary metabolites?

coevolution

when two or more species of organisms influence each other’s evolutionary pathway

one pollinator at risk

specialists

many pollinators at risk

generalists

multicellular

no cell walls (more flexibility)

heterotrophs (animals ingest and digest)

mobility (w/ muscle and nerve cells forming tissues)

mostly sexual reproduction

What are 5 characteristics of animals?

an increase in atmospheric and aquatic oxygen levels

formation of the ozone layer

evolution of hox genes (body differentiation)

an evolutionary “arms race” between prey and predator

What are the 4 probable causes for a sudden increase in animal diversity?

lungs

internal fertilization

amniotic egg with shell

What are three key adaptations that allowed animals to colonize terrestrial environments (prevented them from drying out and enabled them to breath, move, and reproduce on land)

protist; monophyletic

all animals descend from a _____ ancestor, and as a group, animals are _________

1. type of body symmetry

2. number of germ layers

3. specific features of embryonic development

what are the three main morphological and developmental features animals have been traditionally classified using

1. no symmetry (earliest diverging animals like sponges)

2. radially symmetry; often circular or tubular in shape (cnidarians like jellyfish)

3. bilateral: two halves that are mirror images

What are the three types of body symmetry?

endoderm, ectoderm, and mesoderm (specific to bilateria)

*sponges have no germ layers

What are the three germ layers?

endoderm

a type of germ layer; the inner layer, lines the primitive digestive tract

ectoderm

a type of germ layer; outer layer, covers the surface of the embryo and differentiates into the epidermis and nervous system

mesoderm

a type of germ layer; forms muscles and most other organs between the digestive tract and the ectoderm

tripoblastic

having a body derived from three embryonic cell layers (ectoderm, mesoderm, and endoderm), as in all multicellular animals except sponges and coelenterates.

diploblastic

1. having a body derived from only two embryonic cell layers (ectoderm and endoderm) but no mesoderm), as in sponges and coelenterates.

specific features of embryonic development in Bilateria

protostomes and deuterostomes

protostomes

blastopore becomes the mouth (ex. spiralians)

deuterostomes

blastopore becomes the anus (radial cleavage)

determinate cleavage

if a cell is separated in a 4-cell embryo, the development stops

indeterminate cleavage

if a cell is separated in a 4-cell embryo, that one cell as well as the other 3 cells can develop into an embryo (results in identical twins in humans)

coelom

fluid-filled body cavity; cushion for internal organs and allows them to move and grow independently of the outer body wall. In soft-bodied invertebrates, it works as a hydrostatic skeleton, giving support and shape to their bodies

coelomate

cavity completely covered in mesoderm

psueodocoelomate

cavity NOT completely covered in mesoderm

acoelomate

lack a coelom. instead of fluid, they contain mesenchyme tissue

segmentation

the body is divided into regions

evident in some groups (annelids, arthropods), but les so in chordates (fish, mammals, etc.)

allows specialization of body regions

ctenophores

comb jellies; have two long sticky tentacles that trap prey and eats it; digestion occurs in the gastrovascular cavity; the earliest animals

hemaphrodites

an animal having both male and female sex organs or other sexual characteristics, either abnormally or (in the case of some organisms) as the natural condition.

1. have two long sticky tentacles
2. hermaphrodites
3. lacks true HOX genes
4. has 8 rows of cillia that looks like combs
5. THE LARGEST ANIMAL TO USE CILIA FOR LOCOMOTION

What are five features of ctenophores?

ctenophores

earliest divergent lineage of animals

porifera

the phylum of sponges

rotational symmetry

A type of symmetry a figure has if it can be rotated less than 360 degrees about its center and still look like the original.

sponges (porifera)

Most ancestral animals, no body symmetry, no germ cell layers (lack true tissue)

spongocel

large central cavity of the sponge