Biology II Exam Two

Seeds

Reproductive structures produced by angiosperms and other seed plants
Usually as the result of sexual reproduction
Contain embryos that develop into seedlings upon germination
Provide: Food
and Protective coating

Alternation of Generations

there is an alternation between a dipole (2N) plant form (Sporophyte) and haploid (1N) plant form (Gametophyte)

Gametophyte

Haploid, or gamete-producing plant form
Grow and develop within flowers of angiosperm
Produces gametes by mitosis

Sporophyte

diploid or spore-producing plant form
Large "plant" in flowering plants
Produces haploid spores by meiosis
Reduction division
2N to 1N

Syngamy

Fertilization
This process results in the formation of a diploid which undergoes mitosis to form an embryo (multicellular)

What is the embryo considered?

a sporophyte

What are the characteristics of the plant embryo?

a sporophyte that lies dormant in the seed with a supply of stored food and seed coats

What three parts is the plant body composed of?

stems, leaves and roots

What makes up the Shoot system?

stem and leaves

What makes up the Root system?

roots

Stem

produce leaves and branches and bear the reproductive structures

Leaves

flattened structures specialized for photosynthesis

Roots

provide anchorage in the soil and faster efficient uptake of water and minerals (storage)

Indeterminate Plant Growth

Increase in size as long as the plant is alive

What are the three means by which plants grow?

Increase number of cells -> cellular reproduction (mitosis and cytokinesis)
Increase in cell size
Increase in weight

What reproductive structures do mature plants produce?

flowers, seeds and fruits

Flowers are produced by what type of growth?

determinate growth

Flowers and floral buds are

reproductive shoots

Flower tissues enclose and protect

tiny male and female gametophytes

Fruits enclose seeds and function in

seed dispersal

meristem

region of undifferentiated cells that produce new tissues by cell division

Where are dormant meristems in seed embryos?

at root and shoot tips

Mature plants have

shoot apical meristems and root apical meristems

What powers the transformation of seedlings to mature plants?

Photosynthesis

What is the hierarchy of structure in a mature plant?

Specialized cells
Tissues
Organs
Organ systems (branches, buds, flowers, seeds, fruits)
Root and shoot systems
Plant (organism)

Primary Growth

- Elongation of plant organ(s)
- Roots, stems and leaves
- ALL plants
- Produces 6 Primary tissues
derived from apical meristems (RAM, SAM)

Primary xylem

vascular/conducting tissues ; water and minerals

Primary Phloem

vascular/conducting tissues ; food and solutes

Epidermis

dermal (outermost) tissue ; protection (1 cell thick)

Parenchyma

most abundant type ; storage ; part of cortex and pith

Collenchyma

protection/support of growing plant organs ; cortex

Sclerenchyma

protection/support of non-elongating organs ; cortex

Secondary Growth

- Expansion of plant organ(s) [lateral meristems]
- Roots and stems (NOT leaves)
- NOT all plants
- Produces secondary tissues (woody tissues)

What are the two major groups of angiosperms?

eudicots and monocots

Eudicots

- 240,000 species
- All with primary growth ; most with secondary growth
- Ex. Oaks, trees, roses, pansies

Monocots

- 60,000 species
- All with primary growth ; very few with secondary (we will consider it absent)
- Ex. Grasses, corn, tulips, lilies

What are the major functions of the root system?

- Absorbing water and minerals
- Anchoring the plant in soil
- Storing nutrients and water

Eudicots have what kind of roots

taproots

Monocots have what kind of roots

fibrous roots

What are the three regions of root growth?

- Region of Cell division
- Region of Elongation
- Region of Maturation

Region of Cell Division

(root apical meristem and root cap)
- RAM contains cells (divide and keep dividing)
- root tips embedded in lubricating mucigel

Region of Elongation

cells extend by water uptake

Region of Maturation

- root cell differentiation and tissue specialization
- Identified by presence of root hairs (water and mineral uptake) absent from older regions

Epidermis of mature roots

- encloses a cylinder of parenchyma called the root cortex
- Often rich in starch (function as a food storage site)
- May contain intercellular air spaces

Endodermis

selective absorption of minerals / (vascular cylinder)

Meristematic pericycle

- encloses root vascular tissue
- produces lateral (branch) roots

Woody roots produce

primary vascular tissues followed by secondary vascular tissues

What are the 4 parts of shoots?

Stem node, Internode, Leaf, Axillary meristems

Stem node

leaves emerge (or branch)

Internode

stem between adjacent nodes

Axillary meristems

- generate axillary buds
- Can produce flowers or branches (lateral shoot)
- New branches bear a SAM at their tips
- SAM (Shoot Apical Meristem)

Terminal bud

at end of each shoot; includes the SAM and other parts

Eudicots have what venation?

pinnate or palmate (NETTED)
- provide more support to the leaf

Monocots have what venation?

parallel

Stems

mostly above ground organs but some modified stems are below ground

Eudicot stems

- Primary (elongation) and secondary growth (expansion) in most
- Vascular bundles (xylem and phloem) form a 'ringed' pattern exhibit both a cortex and pith

Monocot stems

- Primary growth (elongation)
- Vascular bundles (xylem and phloem) are 'scattered' ; LACK both a pith and a cortex

Lateral Meristems

expansion

Lateral meristems produce

secondary tissues: = 2* Growth

What are the two lateral meristems?

vascular cambium and cork cambium

2 lateral meristems

both are 'rings' that retain cell division properties and produce 'rings' of secondary tissues to the inside/outside of cambium ring

Vascular Cambium

produces ring of secondary xylem (wood) to the inside and ring of secondary phloem (inner bark) to outside

Cork Cambium

produces rings of periderm (outer bark) that replaces the epidermis and cortex for external protection

Cork (outer bark)

periderm

Woody plants

- begin life with only primary vascular systems
- produce secondary vascular tissues and bark as they mature

Secondary xylem

wood

Secondary phloem

inner bark

Bark has both

outer bark (periderm) (mostly dead cork cells) and inner bark (secondary phloem)

Secondary growth in Eudicot stems

- Begins late in the 1st year of growth
- Eudicot stem after 3 years of secondary growth - 3 rings of 2* xylem (=wood)

Eudicot Roots

primary & secondary growth (most), cortex, no pith; core of xylem in the core of root

Monocot Roots

primary growth; cortex and pith

Hormones

- chemical messengers that regulate plant growth
- Most transported in phloem tissues
- ALL require an expenditure of energy on part of plant (ATP) for transport
- Interact with external environment factors to determine growth

Hormones control

Growth
Seed germination
Flowering
Fruiting
Shedding of leaves
Color change

Senescence

degradation of chlorophyll ; color change

What are the two broad categories of hormones?

growth inhibiting and growth promoting

Auxins

- First group of plant hormones described
- Growth promoting hormone
- Produced in:
- Shoot tips, seeds, fruits, leaves, stems (NOT roots)

Auxin effects

Promote cell elongation
Promote shoot elongation
Promote production of wood (2* xylem)
Promote fruit development
Inhibits lateral bud development (axillary buds)
Inhibits abscission (dropping of) of leaves, flowers, fruits

Cytokinins

- Originally detected in coconut 'milk'
- Growth promoting hormone
- Produced in:
- Seeds, fruits, roots

Cytokinin Effects

Promotes cell division (name derived from cytokinesis)
Promotes lateral bud development
Inhibits leaf senescence (change of color due to breakdown of pigments)

Gibberellins (gibberellic acid)

- Many types (more than any other group)
- Growth promoting hormone
- Found throughout plant but concentrated in seeds
Inside embryonic plant in seed

Gibberellins Effects

Promotes stem elongation by stimulating cell division and elongation
Promotes breakdown of food (starch) reserves in germinating seeds

Steps with gibberellin release

- Intake of water causes swelling and embryo hydration
- Embryo secretes gibberellins
- Gibberellins transported to cells of aleurone layer to secrete enzyme
(alpha-amylose) for breakdown of endosperm to glucose
- Embryo will respire glucose to produce ATP
- Embryo is directing the timing of germination
- ADVANTAGE of SEED PLANTS

Brassinosteriods

Growth promoting hormone

Brassinosteriod Effects

Promotes cell expansion
Promotes shoot elongation
Promotes shoot elongation
Promotes xylem tissue development
Promotes stress response
Inhibits lead abscission (dropping)

Abscisic Acid (ABA)

Growth inhibiting hormone
Found in large quantities in seeds moisture leaves, and dormant buds

Abscisic Acid Effects

Inhibits cell elongation
Inhibits alpha-amylase production
Promotes leaf senescence
Promotes production of storage proteins in seeds

Ethylene

Growth inhibiting hormone
Actually a gas produced by incomplete metabolism

Ethylene Effects

Promote fruit ripening
Promote abscission of leaves, fruits, flowers
Interacts with 4 growth promoting hormones to determine cell size/shape

Seed germination

Requires breaking of dormancy- combination of internal and external factors (environmental conditions)

Internal development of seedlings

Cells -> tissues -> organs -> organism

Nutrient

substance metabolized by or incorporated into an organism

What does photosynthesis require?

CO2, water, and elements such as potassium, nitrogen, and calcium

All but what is primarily taken up from the soil?

CO2

Deficiency symptoms

develop in plants that receive too little of a nutrient

Essential elements

play many roles in plant metabolism, often functioning as enzyme cofactors

Macronutrients

required in amounts of at least 1 g/kg of plant dry mass (>)

Micronutrients or trace elements

required in amounts at or less than 0.1 g/kg of plant dry mass (<)

Limiting factors

resources that can limit growth
Light
Carbon dioxide
Water
other mineral nutrients

13 soil nutrients

absorbed dissolved in H2O through roots and all follow the same pathway through plant as H20 (XYLEM)

Nitrogen (N)

macronutrient
component of proteins, nucleic acids, chlorophyll