Exam 2 Flashcards
The floral structures are attached in a circle of the flower where are the sepals and petals
The outer layer of the circle contains sepals which are usually green and enclose the flower before it opens
The next layer after the sepals are removed there are the petals these are very noticeable and attract pollinators and these petals are the key to the success of angiosperms
What is revealed when the flower petals are removed
The stamen filiments
What is at the top of each stamen filament
The anther
Describe the anther
A sac containing the male sporangia this will eventually release pollen
Where is the carpel located and what does it do
The structure located at the centre of the flower
This is the female reproductive structure including the ovary
A unique adaptation which enclosed the ovules
Each ovule contains a sporangium that will produce a female gametophyte and eventually become a seed
The ovary will mature into a fruit which aids in seed dispersal
Angiosperms are a group of plants that are
Sporophyte dominant
The gametophyte generation of angiosperms is produced where
Its body
Where does meiosis occur in angiosperms
Within the anther of the flower
This produces haploid spores which undergo mitosis
These will form the male gametophyte (pollen grains)
Meiosis in the ovule produces what
A haploid spore that undergoes mitosis
This forms the few cells of the female gametophyte
One of these cells is destined to become an egg
Pollination of angiosperms occurs when
A pollen grain lands on the stigma
The pollen grain is carried by either wind or an animal
A tube grows from the pollen grain to the ovule and a sperm fertilizes the egg (same as in gymnosperms)
This forms a zygote
In angiosperms a seed develops from each ovule and each seed consists of
An embryo surrounded by a seed coat and a food supply
The embryo is a new sporophyte
As the seed develops in angiosperms the ovaries wall thickens and forms what
The fruit that encloses the seeds
When conditions are favourable for the angiosperms the seed germinates and …
The embryo grows it uses the food supply from the seed until it can begin photosynthesis
Eventually it develops into a mature sporophyte completing the life cycle
What is a key adaptation of angiosperms
The flowers attract animals which carry pollen more reliably then wind
They are also able to produce seeds very rapidly - fertilization occurs just 12 hours after pollination
Describe fruits
The ripened ovary of the flower
Aids in seed dispersal
Explain the stages of fruits
During development the fruits remain green and thus camouflaged
When ripe fruit becomes bright this attracts animals
When the fruit is eaten the seeds will be deposited by the animal
Not all flowers have colourful accessories and sweet scents what is an example of this
Red maple
Has many anthers but no petals and relies on wind for pollination
To work massive amounts of pollen must be produced to endure that some make it to another plant and fertilization takes place
The columbine has an elaborate flower vibrantly coloured what are the advantages and disadvantages
This is associated with a high energy cost
This investment pays off when a pollinator carries the plants pollen to another flower
Because the pollinator is attracted to the flower
What supports the fact that about 90% of angiosperms use animals for pollination
Animals visit the flowers in search of a meal
Flowers provide meal in form of nectar which is a high energy fluid
The colourful petals and strong fragrance mark the plant as a good source
Two major groups of angiosperms are what
Monocots and
Eudicots
How are angiosperms classified into monocots and eudicots
According to the first leaves that appear on the plant embryo
These embryonic leaves are called seed leaves or cotyledons
How many cotyledon’s do monocots have and how many do eudicots have
Monocots - 1 cotyledon
Eudicots - 2 cotyledon
Give examples of monocots
Large group of related plants including lilies and orchids
What are the characteristics of monocots
Leaves with parallel veins
Stems contain vascular tissues arranged in scattered bundles
Flowers contain petals and other parts in multiples of three
Roots from a shallow, fibrous system spreading out below the soil surface ; this arrangement permits a huge surface area which reduces erosion
Give examples of eudicots
Included most shrubs and tress crops fruits and vegetables
Most angiosperms are eudicots or monocots
Eudicots
What are the characteristics of eudicots
Multi-branched network of veins Vascular bundles arranged in a ring Petals and other parts are found in arrangements of four or five Root is large and vertical -> taproot Goes deep into the soil
The plant body contains three basic organs
1) roots
2) stems
3) leaves
Each are composed of different tissues
Organ structure correlates nicely with function
What are the two systems of a plant
Root system
Shoot system
Describe the root system
Anchors the plant in the soil
Absorbs and transports minerals and water
Stores food
Near the root tips is an abundance of root hairs
- increases surface area for absorption of water and minerals
Describe the shoot system
Made of stems and leaves
Also reproductive structures such as flowers
What are the four parts of the shoot system
Stems
Nodes
Internodes
Leaves
Describe the stems
Above ground
Supports leaves and flowers
Describe the nodes
Point at which leaves are attached
Describe the internodes
Portions of the stem between the nodes
Describe the leaves
Main photosynthetic organs
Composed of a flattened blade and a stalk called a petiole which joins the leaf to the node of the stem
What are the two types of buds
Terminal buds
Axillary buds
Describe terminal buds
At the apex tip of the growing stem
Has developing leaves and a compact series of nodes and internodes
Describe axillary buds
These are within the angle between the leaf and the stem
Usually dormant
Describe apical dominance
Hormones produced by the terminal buds inhibit their growth
Axillary buds allow concentrating resources toward growing taller and increases the plants what
The plants exposure to sunlight and is important when vegetation is dense
Under some conditions the axillary buds begin to grow and what occurs
The growth removes the terminal bud and often stimulates the growth of the axillary bud
What are the three modified stems
Horizontal stem (runner)
Rhizomes
Bulbs
Describe horizontal stem
Aka runner
Grows along the ground surface
Allows the plant to reproduce asexually
Describe rhizomes
Horizontal stems that grow either right below or along the surface of the soil
They store food and may also spread and form new plants
Potato plants have rhizomes which end in enlarged structures called tubers which are specialized for storage (the potato)
Describe bulbs
Underground shoots which contain swollen leaves for food storage
What are the two types of modified leaves
Tendrils
Spines
Describe tendrils
The tips are coiled around a stem
This helps the plant to climb such As in a grapevine
Describe spines
Of a cactus are a modified leaf that protects against being eaten by animals
Define a tissue
Group of cells with a common structure function or both
Define a tissue system
Composed of one or more functional units within a plant
The plant root stem and lead are all made of three tissue systems
1) dermal tissue
2) vascular tissue
3) ground tissue
The three tissue systems have different arrangements in different organs
What are the four types of eukaryotes
Protists
Plants
Fungi
Animals
Explain protists
Eukaryotes Unicellular (mostly) Diverse group and live in diverse habitats Some are autotrophic = algae Some Heterotrophic = protozoans Some are both = mixotrophs
Explain protists diverse habitat
Most are aquatic
Can be found almost anywhere with water ie) damp soil and ponds
Some protists inhabit host organisms
Define endosymbiosis
Give an example
Refers to one species called an endosymbiont living within another species
Ie) termite endosymbiont leaves in the gut of a termite and digests the tough cellulose in the wood diet of the termite
They live in harmony
Define symbiosis
Refers to a close relationship between organisms of two or more species
What is the simplest group of eukaryotes
Protists
What are the 5 subgroups of protists
1) Chromalveolata
2) Rhizaria
3) Excavata
4) Unikonta
5) Archaeplastida
How did eukaryotes originate
The theory is endosymbiosis
When small prokaryotes established residence in larger prokaryotes
What evidence supports the endosymbiosis theory of eukaryote origin
There are similarities between prokaryotes and present day mitochondria and chloroplasts
Who is said to have evolved first
Heterotrophic eukaryotes
Or
Autotrophic eukaryotes
Heterotrophic
Have no chloroplast and can not preform photosynthesis
How where autotrophic eukaryotes said to have originated
When an individual engulfed an autotrophic Cyanobacterium (these are photosynthetic bacteria)
Eventually the Cyanobacterium turned into a chloroplast
This later created green and red algae
What happened to the red and free algae during the evolution of protists and eukaryotes
The green and red algae became endosymbiont when engulfed by heterotrophic eukaryotes
Define secondary endosymbiosis
The process when an autotrophic eukaryote protist became endosymbiotic in a heterotrophic eukaryotic protist
What are the five types of chromalveolates
1) diatoms
2) dinoflagellates
3) brown algae
4) water molds
5) ciliates
What are the two types of Rhizarians
1) foraminiferans
2) radiolarians
What are the two types of unikonts
1) plasmodial slime molds
2) cellular slime molds
What are the two types of archaeplastids
1) red algae
2) green algae
Describe diatoms
Unicellular Glassy cell wall with silica and has two halves of the cell wall that fit together like a box Autotrophic Found in marine and freshwater Produce important food for aquatic life They form their food in sugar droplets
What are the two advantages of diatoms sugar and oil droplets
Rich source of energy
Oil makes the diatoms buoyant and keeps them floating near the surface of the water where sunlight is plentiful
Fossilized diatoms form what
Sediment
Diatomaceous earth
Describe dinoflagellates
Found on marine and freshwater plankton
Some are hetero/auto/mixotrophic
What happens when dinoflagellates bloom
They can cause warm coastal waters to turn pinkish orange which is called the red tide
And produce toxins which have killed large quantities of fish
Describe brown algae
Large and complex Autotrophic ALL Are multicellular Most are marine What we commonly call seaweed (Kelp)
What is brown algae brown
Due to their pigments in their chloroplasts
Describe water molds
Heterotrophic Unicellular Fungus like Decompose dead plants and animals in freshwater habitats Some grow on the skin and gills of fish
Describe ciliates
Large and diverse group
Use cilia for movement and feeding
Unicellular
Heterotrophic and mixotrophs
What is an example of ciliates
Paramecium
What do chromalveolates also include
What do these cause and how are they transmitted
Plasmodium
Cause malaria and transmitted by mosquitoes
What are Rhizarians referred to and why
Amoebas
Because they move and feed using pseudopodia
Why are Rhizarians pseudopodia different then other amoebas
Their pseudopodia is thread like rather then the typical lobe like
Describe foraminiferans
Found in ocean and freshwater
Have tests
Define tests
Tests are porous shells composed of organic material hardened by calcium carbonate
Pseudopodia extend through the small holes in the test
What do fossilized tests form
Sedimentary rock
Describe radiolarians
Produce an internal skeleton made of silica
The cell is also surrounded by a test of organic material
Many species are marine
When they die they settle at the bottom of the ocean and become sediments
Describe excavata
Autotrophic heterotrophic mixotrophs
Likely the most ancient type of eukaryote
Has a modified mitochondria with no electron chain
Are anaerobic (use glycolysis for ATP)
Who are likely the most ancient eukaryotes
Excavata
What are some examples of excavatas
Giardia intestinalis -waterborne parasite causes diarrhea Trichomonas vaginalis (via sex) Trypanosoma spp (via bugs) Euglena spp (found in pond water)
Define a parasite
Derive nutrition from their host, and the host is harmed during the process
Describe unikonts
Use pseudopodia to move and feed Includes: -free living amoebas -some parasitic amoebas -2 types of slime molds
Describe plasmodial slime molds
Commonly found where these is moist decaying organic matter
Brightly pigmented
Unicellular
DIFFERENT then the plasmodium that causes malaria
Uses pseudopodia
Moves cytoplasm as one in a pulsing flow to move nutrients and oxygen
What happens when food is limited for the plasmodium
The plasmodium stops growing and differentiates into reproductive structures that produce spores
When conditions are favourable the spores release haploid cells that fuse to form a zygote allowing the life cycle to continue
Describe cellular slime molds
Common on rotting logs and decaying organic matter
Usually they exist as solo amoeboid cells
What happens to cellular slime molds when nutrients are scarce
They swarm together forming a slug like clump of cells that travels around for a short time
Some of these cells will then dry up and form a stalk
What does the stalk do for cellular slime molds
Supports an asexual reproductive structure
In this structure cells develop into spores
Describe archaeplastids
Mainly autotrophic
Red green algae and land plants
Describe red algae
Live in warm coastal waters of the tropics
Red because of an extra pigment that masks the green
Most are multicellular
Most are soft bodied but some have hard deposits on their cell wall
Where do you find hard bodied red algae
On coral reefs
Describe green algae
Green coloured
Unicellular
Colonial and multicellular members
Generally have complex life cycles
What is an example of a green algae with a complex life cycle
Multicellular Ulva
Complex life cycle of multicellular green algae is characterized by what
By an alternation of generations
How is green algaes life cycle an alternation of generations
Multicellular diploid form (2n) alternates with a multicellular haploid (n) form
This alternation of generations occurs in many multicellular algae as well as plants
Define gametophytes
Multicellular haploid form
Define sporophytes
Multicellular diploid form
Explain the evolution of multicellularity
1) an ancestral colony of flagellated protists may have formed (when a cell divided and offspring remained attached)
2) cells of the colony may have become slightly specialized and interdependent (more efficient)
3) additional specialization may have led to differentiation in between sex cells and non reproductive cells
Why was early life on land perfect for plants
There was an abundance of sunlight and carbon dioxide
There were very few pathogens and plant eating animals
What differentiates multicellular algae from multicellular plants
Plants under went certain key adaptations that needed to take place in order for them to be able to live on dry land
What are some of the key differences between algae and plants
Algae
- anchored but no ridged tissues supported by water contains minerals and CO2 directly from the water the entire organism has access to light, flagellated sperm swim to the egg and offspring are also dispersed by water
Plants
- surrounded by air and has mechanism to keep water in cells, gets nutrients from soil and air, has to support itself, has to reproduce without the use of water
What are the four plant adaptations for life on land
1) maintaining moisture
2) obtaining resources from very different environments
3) supporting the plant body
4) reproduction and dispersal
Explain the plants adaptation to maintain moisture
The portions of land plants that are above the ground are covered with a waxy cuticle that prevents water loss
CO2 and o2 cannot diffuse across the cuticle so the pores on the leaves function in gas exchange
What are the pores called on the leaves of plants and how are they regulated
Stomata
Surrounding cells regulate the opening and closing of the pores
Usually stomata is open during the day allowing gas exchange and closed during the night to prevent water loss
Explain the plants adaptations to obtaining resources from different environments
Plants must obtain resources from both the soil and the air
Water and nutrients are found in the soil
Light and CO2 is found in the air
Roots stems and leaves help to fulfill these requirements
Describe the roots and how they help in obtaining resources from different environments
Provide anchorage
Absorb water and mineral nutrients from the soil
Describe the stems and leaves and how they help to obtain resources from different environments
The leaves capture CO2 which enables photosynthesis
Apical meristems are growth producing regions that are found near the tips of both roots and stems
Elongation and branching act to maximize exposure to resources found within the soil and air
How do vascular and avascular tissues help obtain resources from different environments
The xylem functions to move water and minerals up from the roots
The phloem functions to move sugars up and down the plant
Avascular
-few plants are avascular and are restricted with height because they have limited means to distribute water and minerals from the soil and air
Define apical meristems
Growth producing regions that are found near the tips of both roots and stems
What are the two types of tissues in plants
Vascular
Avascular
What are the two types of vascular tissues
1) xylem - move water up from roots and are composed of dead and living cells
2) phloem - move sugars up and down the plant and composed of ONLY living cells
Explain the plants adaptations of supporting the body
They must be able to hold themselves up against gravity
Cell walls of some plants are thickened and reinforced by a chemical called LIGNIN
What is the chemical called that reinforces and thickens the cell wall what happens when there is an absence of this chemical
Lignin
Causes a height limitation
Explain a plants adaptations of reproduction and dispersal
Plants must be able to keep their gametes developing embryos from drying out in the air
Where do mosses and ferns produce gametes
Within the female and male gametangia
Define the gametangia
Structures made of a protective jacket of cells surrounding the gamete producing cells
Why can mosses and ferns only reproduce in moist environments
Because male gametes are released and swim to the female gametangium where the egg remains and this requires water!
What do pines and flowering plants have for reproduction
Pollen grains
Describe pollen grains
Structures that contain the sperm producing cells
These are brought close to the egg by wind and animals this does not require moisture
What occurs to the zygote in all plants
The zygote (fertilized egg) develops into an embryo while still attached to the parent plant
Define the embryophyte
What the embryo is called when multicellular and dependent
Key difference between plants and algae
What does the haploid generation produce during the alternating generation
Eggs and sperm
What does the diploid generation produce during the alternating generation
Produces spores within a structure called a sporangium
What can spores develop into
A new organism without fusion with another cell
What types of plants uses spores for dispersal and what plants use seeds
Mosses/ferns= spores Pines/flowers= seeds
Define seeds
Elaborate embryo containing structures that protect the embryo from elements that are dispersed by wind or animals
Plants that do not use seeds to disperse their offspring are referred to as what
Give an example
Seedless plants
Ie) mosses and ferns
Define bryophytes
Seedless avascular plants that were first to arise
Describe bryophytes and give an example
Lack true roots and leaves
They resemble all other plants because they have apical meristems and embryos that develop while attached to the parent plant
They do not have lignin so don’t grow very tall
Found in spongey mats or growing in dense mats
Ie) mosses
Describe vascular plants
Have lignin in cell walls
Provide strong support allowing for them to stand straight and grow tall
What are the two primary groups of vascular plants
Seedless vascular plants
Seeded vascular plants
Describe seedless vascular plants
Includes ferns
These have well devolved roots and stems common in forests but are more diverse in the tropics some can grow several meters tall
Do not require moisture for reproduction
They disperse their offspring as spores carried through the air
Describe seeded vascular plants
Accounts for more then 90% of the species
Seeds and pollen improved the plants ability to live on land
Define seeds
Contain an embryo and a food supply contained within a protective coating
Package of survival
Facilitated the dispersal of plant embryos over wide distances
Define pollen
Brings sperm producing cells into close contact with egg-producing parts
Water is not necessary for fertilization
Pollen is able to travel large distances
What are the two main groups of seeded plants
1) gymnosperms (earliest seed plants)
2) angiosperms
Define gymnosperms
The earliest lineage of seeded plants
Gymno = naked
Seeds are not produced in chambers
What is the largest group of gymnosperms
Conifers
Cone bearing trees ie pine
Define angiosperms
The most recent episode in plant evolution
These are flowering plants
Angio= container
Refers to the fact the seed is produced within a specialized chamber
Flowers are complex reproductive structures that develop seeds within protective chambers
Summarize the evolution of plant adaptations
1) dependent embryos are present in all plants
2) lignified vascular tissues mark a lineage that gave rise to most vascular plants
3) seeds are found on all gymnosperms and angiosperms and dominate the plant kingdom today
4) flowers are the makers of the angiosperm lineage
What are the stages of the plant life cycle
1) haploid gametophyte plants produce gametes (sperm and egg) by mitosis
2) fertilization produces a diploid zygote
3) the zygote divides by mitosis and develops into a multicellular diploid sporophyte plants
4) the sporophyte produces haploid spores by meiosis
5) spore then develops by mitosis into a multicellular haploid gametophyte
Mosses are___. The cushiony green growth of the moss is the _____
Gametophyte dominant
Gametophyte
5 stages of moss life cycle
1) gametes develop in male and female gametangia
2) after fertilization the zygote remains in the gametangium
3) in the gametangium the zygote divides by mitosis
4) meiosis occurs in the sporangia at the tips of the sporophyte stalks
5) spores undergo mitosis and develop into gametophyte plants
Where is the gametangia usually located in mosses
On separate plants
Flagellated sperm swims through a water film to reach the egg in the female _____
Gametangium
In mosses after the zygote divides by mitosis what does it develop into
Sporophyte embryo and then mature sporophyte
The sporophyte remains attached to the gametophyte
Following meiosis in moss the haploid spores are released from the ____
Sporangium
Describe ferns and it’s life cycle
Sporophyte dominate
1) gametophyte is very small (heart like shape and sperm needs moisture)
2) the zygote remains on the gametophyte
3) the zygote develops into an independent sporophyte
4) within the clusters of sporangia cells undergo meiosis producing haploid spores which are then released
5) spores develop into gametophytes by mitosis
In gymnosperms what is the specialized structure within the sporophyte that all stages of reproduction occur
The cone
Each scale of the cone contains sporangia which produce spores by meiosis
What are the two types of cones that pine trees have which produce spores
Pollen cones
Ovulate cone
Describe the pollen cone
Produces male gametophytes
Smaller cones
Contain sporangia which produce many haploid spores by meiosis
Male pollen grains (gametophytes) develop from these spores
Mature pollen cones release millions of microscopic pollen grains in clouds and are carried by wind
They contain cells that will develop into sperm if they land on a cone containing a female gametophyte
Describe the ovulate cone
Produces the female gametophyte
Larger cone
Each scale contains a pair of ovules
Each ovule contains a sporangium covered by a protective covering
What is the protective covering around the sporangium in the ovule called
Integument
When does pollination occur in gymnosperms
When a pollen grain lands on an ovulate scale and enter an ovule
Following pollination the scales grow together sealing the cone until the seeds are mature
Now meiosis occurs in a spore mother cell within the ovule
Over the course of months how many haploid spores will survive and develop into the female gametophyte in gymnosperms
ONE
this gametophyte will produce eggs
A tiny tube grows out of the pollen grains and this tube digests its way through the ovule and eventually sperm is released near an egg
How long after pollination in gymnosperms will fertilization usually occur
More then a year after pollination
All eggs in an ovule are usually fertilized but ____
Only one of these zygotes will fully develop into a sporophyte embryo
Under favourable conditions the seed will do what in gymnosperms
Will germinate and it’s embryo will develop into a pine seedling
The ovule will mature into a seed in gymnosperms and do what
The seed contains the embryos food
The food supply is the remains of the female gametophyte
The seed coat is the ovules integument
Typically seeds are shed two years after pollination
The seeds disperse by wind
Where is the site of pollination and fertilization on angiosperms
The flowers
They house separate male and female sporangia and gametophytes
How do flowers differ from pine cones
Each structure of the flower is highly specialized for very different functions
Describe the dermal tissue system
Forms an outer protective covering
First line of defence against physical damage and infectious organisms
What does the dermal tissue system consist of
Epidermis - single layer of tightly packed cells
Cuticle - waxy outer covering atop the epidermis protects against water loss
Describe vascular tissue
Composed of xylem and phloem tissues
Provides support and long distance transport
Describe ground tissue
Not dermal or vascular
Accounts for the bulk of a young plant
Fills the space between the vascular tissue and the epidermis
This system function is support storage and photosynthesis
ground tissue internal to the vascular tissue is the
Pith
Ground tissue external to the vascular tissue is the
Cortex
Describe the vascular cylinder
Two types of cells
Vascular tissue system in the centre of the root
Xylem cells
Phloem cells
Xylem cells of dicot are found where
Radiate from the centre like spokes of a wheel
Ring of xylem cells found in root of monocots
Phloem cells of dicot are found where
Fill the wedges between the spokes
Ring of phloem cells found in root of monocots
The region between the vascular cylinder and the epidermis consists entirely of ___
Correct
Define cortex cells
Store food and starch and take up minerals that have entered the root via the epidermis
Define the epidermis
The inner layer of the cortex
A cylinder that is one cell layer thick
A selective barrier that determines which materials can pass between the rest of the cortex and the vascular tissue
Eudicots and monocots have different stem arrangements explain:
Both have vascular tissues arranged in vascular bundles
Monocots - has vascular bundles scattered throughout the ground tissue
Eudicots - has vascular bundles arranged in a ring
What do eudicot stems have unlike roots
Are monocots the same
Has both a cortex region and a pith region
No they are not divided into pith and cortex regions
Describe the stomata
Interrupt the epidermis
Allow gas exchange
Each stoma is bordered by two guard cells that regulate the size of the stomata opening
The ground tissue between the leaf is called what and is between what
Mesophyll
Between the Upper and lower epidermis
Consists predominantly of photosynthetic parenchymal cells
Where chloroplasts are located
Eudicots and monocots have vascular tissue on the leaf made up of a network of ___
Veins
Each vein has a vascular bundle composed of __ and __
What does this do
Xylem and phloem
Gives leaf it’s shape and helps carry out photosynthesis by circulating
What are the three structures that distinguish plants from other eukaryotes
Chloroplasts
Central vacuole -contains fluid for shape
Cell wall
Many plants have two cell walls what are they
Primary cell wall
(Laid down first)
Secondary cell wall
(Ridged laid down second and is between the plasma membrane and the primary cell wall)
Define the middle lamella
A sticky layer that holds the primary cell walls of adjacent cells together
What are pits
Regions where the cell wall is relatively thin allowing the migration of water between adjacent cells
Define plasmodesmata
Channels of communication and circulation between adjacent plant cells
What are the five types of plant cells
1) parenchymal cells
2) collenchyma cells
3) sclerenchyma cells
4) water conducting cells
5) food conducting cells
Define parenchymal cells
Most abundant cell type
Have only primary cell walls which are thin and flexible
Preform most metabolic plant function
-photosynthesis
-aerobic respiration
-food storage
-most can divide and differentiate into other types of plant cells
Define collenchyma cells
Do not have secondary cell walls
Usually have thicken primary cell walls
Provide flexible support in parts of the plant that are still growing
Young stems and petioles often have collenchyma cells just below their surface
These cells remain alive and elongate as stems and leaves grow
Define sclerenchyma cells
Have thick secondary cell walls
Strengthened with the lignin
Mature cells cannot elongate and thus are found in regions of the plant that have stopped growing
Most are dead at maturity
These cells form a rigid cell skeleton to support the plant
There are two types of sclerenchyma cells what are they
Fibers - long and slender and often arranged in bundles
Sclereids - shorter then fibre cells have thick irregular and very hard secondary walls
Cells responsible for the hardness of nutshells
Describe water conducting cells
Have rigid lignin containing secondary cell walls
Chains come from tubes by overlapping their end
Carries water from the roots to the stems and leaves as part of the xylem tissue
These tubes are hollow and the cells dead when they are mature and only their cell walls remain
Rigid thick walls allow these cells to function in support
What are the two types of water conducting cells
Tracheids -long thin cells with tapered ends
Vessel elements - wider shorter and less tapered
Describe food conducting cells
Sieve-tube members are arranged end to end like xylem forming tubes
Remain alive at maturity but loose most organelles (nucleus and ribosomes)
Allows more room for the transport materials
End walls have sieve plates containing pores that allow fluid to flow from cell to cell
Describe companion cells in food conducting cells
Alongside each sieve tube cell (at least one) connected by plasmodesmata and function to supply the cell with proteins
Define primary growth of plants
Lengthens roots and shoots
Most plant species experience ____ meaning that they continue to grow for the duration of their life
Indeterminate growth
Most animals experience ___ meaning that they cease growing after a certain length
Determinate growth
Angiosperms are characterized according to life cycle duration what are the three types
1) annuals - complete lifecycle in one year or less (crops)
2) biennials - complete lifecycle in two years (beers/carrots)
3) perennials - live and reproduce for many years (trees shrubs ext)
Do plants die from old age?
No they die from environmental factors
Plant growth is made possible by tissues called____
Meristems
Define meristems
Consist of cells that divide frequently generating more cells
Some of these new cells remain in the meristem and continue to divide while others differentiate being incorporated into the tissues of the growing plant
Define apical meristems
Located at the tips of roots and the buds of shoots
Cell division Helps produce new cells allowing the plant to grow in length called primary growth
Enables roots to push through the soil and shoots to increase exposure to light and CO2
Roots and shoots lengthen using different mechanisms
Explain root growth
The tip of the root is covered by a root cap which protects the cells of the apical meristem which are actively dividing
Growth in length occurs just behind the root tip with three areas of distinct cells which are..
1) the zone of cell division
2) the zone of elongation
3) the zone of maturation
(No sharpe boundaries between these three areas)
Explain the zone of cell division
Contain the cells of the root apical meristem and cells that derive from it
New cells of the root are produced here including root cap cells
Explain the zone of elongation
Root cells here elongate (as much as ten times their original length)
Pushes the root tip further into the soil
Cells lengthen and do not expand because of cellulose fibre arrangement
Cells take up water and the cellulose fibres separate expanding like an accordion
Explain the zone of differentiation
All three plant tissues complete their development here
(Dermal ground and vascular tissues)
Cells in the vascular cylinder differentiate into primary xylem and primary phloem
Differentiation occurs because of differential gene expression
Define secondary growth of plants
Woody plants continue to grow in the girth once primary growth is complete
Occurs because of activity in dividing lateral meristems that are arranged into cylinders called vascular cambium and cork cambium
Define lateral meristems and how are they arranged
Where cells divide to cause secondary growth
Arranged into cylinders called vascular cambium and cork cambium
Define vascular cambium
Cylinder of meristem cells one cell thick between the primary xylem and primary phloem
Secondary growth adds layers of vascular tissue on either side of the ____
Vascular cambium
The vascular cambium gives rise to two new tissues that are ..
Secondary xylem (the interior of the vascular cambium)
Secondary phloem
(The exterior of the vascular cambium
Secondary xylem composes _____
The wood of the tree cell walls are rich in lignin providing characteristic wood strength
When secondary growth begins the epidermis sloughs off and is replaced by ____
Cork (the new outer layer)
Describe cork
Mature cork cells are dead and have thick waxy cell walls that protect the under layers
Cork is produced by what
The cork cambium which first forms from parenchymal cells within the cortex
Everything outside the vascular cambium is called ___
Bark
Main components are secondary phloem cork cambium an cork
Youngest secondary phloem functions in sugar transport and older secondary phloem dies
When no cortex remains it forms from ____
Parenchymal cells in the phloem
The bulk of the tree is ____
Dead tissue
What does the living tissue of the tree consist of
Vascular cambium
Youngest secondary phloem
Cork cambium
And cells in the wood rays
Define wood rays
Consist of parenchymal cells that transport water and nutrients
They also function in nutrient storage
Define heartwood
Trunk cells Older secondary xylem No water transport Clogged with resin Will not rot
Define sapwood
Younger secondary xylem
Conducts xylem sap
Fertilization of flowering (angiosperms)
Diploid plant body is the sporophyte
The sporophyte produces specialized structures which cells undergo meiosis in order to become a multicellular gametophyte
Sporophyte in angiosperms produces what type of specialized reproductive structures
Anthers
Ovules
The gametophyte of angiosperms is the plants _____ generation which produces ______ by _____
Haploid
Gametes
Meiosis
Spores in the ___ give rise to the ___ gametophytes which are ____
Anthers
Male
Pollen grains that produce sperm
A spore within an ovule produces the ____ which is the ____ gametophyte containing an _____
Embryo sac
Female
Egg cell
Pollination of angiosperms is ___
The arrival of pollen grains into a stigma
A pollen tube grows into the ovule and sperm passes through it fertilizing both the egg and a second cell called ____
Double fertilization
The ovule develops into a seed and is now a ____ and its nucleus divides by mitosis and produces ____
Triploid (3n)
Endosperm
The zygote divides by mitosis producing the embryo and the ovule looses most of its water and develops a _____ enclosing the endosperm and the embryo
Resistant seed coat
The seed may remain dormant and only begin to grow when ____
Favourable environmental conditions occur (seed dormancy)
Describe eudicots seeds
Two cotyledons
Apical meristems lack protective sheaths
Endosperm is absorbed by the cotyledons
Describe monocot seeds
Single cotyledon
Apical meristems have a protective sheath
Endosperm is present
Hormonal changes which Occur as a result of fertilization trigger the ovary to develop into a ___
Fruit
The fruit functions to ___
Protect the seed and to aid in dispersal
Mature fruits may either be fleshy or dry
Fleshy fruits= oranges
Dry fruits= beans
Seedling germination occurs when…
When a seed absorbs water
The seed begins to expand as a result of water absorption causing the seed coat to rupture
The embryo now begins to grow and produce enzymes
The enzymes function to digest the endosperm releasing nutrients that can be used as energy
Define vegetative reproduction
Asexual reproduction
Involved fragmentation of the plant body
Each fragment gives rise to a genetically identical daughter plant
Ie) garlic
Explain plant importance
Provides shelter for animals fungi and bacteria
Provides food for animals
Roots function to prevent erosion of soil
Photosynthesis reduced atmospheric CO2 and provides the atmosphere with o2
Plants benefit humans immensely
-lumber paper food industrial chemicals ext
Explain how plants acquire nutrients from soil and air
Plant roots absorb water minerals and oxygen from the soil
Leaves take CO2 from the air
Photosynthesis uses water CO2 and minerals to produce sugars composed of carbon oxygen and hydrogen
Inorganic ions such as nitrogen and magnesium are components of photosynthetic pigments
Inorganic ion phosphorus is a major component of DNA and RNA as well as ATP and phospholipids
Describe plants control of solute uptake
The absorptive surface area of the root is dramatically increased by the presence of root hairs
Water and solutes must first enter the xylem before they can be transported up the plant body
To enter the xylem the water may either move through cells (intracellular route) to move through the epidermis and the cortex
Or it may move between the cells (extracellular route)
Explain the intracellular pathway of solute uptake
Moves through the cell membrane of a root hair
Through the plasmodesmata then through the cytoplasmic content of the cortex cells and endodermal cells finally into the xylem vessels
Explain the extracellular pathway of solute uptake
Moves through the cell wall of all epidermal and cortex cells and within intracellular spaces
The waxy barrier called the Casparian strip in the walls of the endodermal cells forces the water through the endodermis and into the xylem
Describe transpiration
Pulls water up the xylem vessels
Root pressure can only push the xylem sap up a few meters
Solute transport raises the water pressure in the xylem
The xylem sap is pulled upward from the soil through a transpiration cohesion tension mechanism
Define xylem sap
Inorganic nutrient solution that travels up xylem from a plants roots and shoots
Define transpiration
Loss of water from the leaf
Exerts a pull on xylem sap
Cohesion causes the water molecules to adhere to one another
Relays the pull of transpiration along a string of water molecule all the way to the roots
The adhesion of water molecules to the exterior of the xylem cells aids to combat the force of gravity
Explain guard cells
Surround the stoma and control the opening thus controlling transpiration
As the guard cells open the stomata they actively pump potassium in increasing the solute concentration within the cell
Water follows the solutes because of osmosis
When the stomata looses K the guard cells close
What are the 3 cues for the stomata opening
1) increased sunlight cause the guard cells to take up K if water is lost too fast the guard cells close
2) decreased internal CO2 has the same effect as increase sunlight
3) an internal daily timing mechanism triggers K uptake and stomata opening in the morning and stomata closing in the evening
Describe the phloem
Transports sugars made by photosynthesis via a pressure flow mechanism
Explain the phloems pressure flow mechanism
1) sugar is loaded into phloem tube at the source which raised the solute concentration within the tube
2) water is the drawn into the tube by osmosis raising the tube pressure
3) sugar and water leave the tube at the sugar sink
(The increase in pressure at the sugar source and decrease in the pressure at the sugar sink causes the sap within the phloem to move from source to sink
Describe fertilizers
Help to prevent nutrient deficiencies
The availability of nutrients within the soil affect plant growth and health
The absence of certain nutrients lead t particular plant symptoms which can be identified
The addition of inorganic fertilizer or compose to soil can alleviate these deficiencies
Stunting of growth wilting of the plant and changes in the colour all indicate nutrient deficiencies
Describe nitrogen deficiencies
Most common
Stunted growth and yellow/green leaves
Affects the older leaves first
Describe phosphorus deficiencies
Second most common
Sometimes purplish leaf colour
Reduced growth rate
Spindly and brittle new growth
Describe potassium deficiencies
Yellow leaves with brown margin
Localized symptoms
Stunted growth
