UCF Principles of Plant Science Exam 1

Two systems of plant organs

Shoot system and Root system

What does the shoot system consist of?

vegetative organs like stems and leaves/ reproductive organs like flowers and fruits

What does the root system consist of?

Only roots

What are the characteristics of determinate growth?

-Growth is genetically determined

-Usually cannot regrow or heal

-Maximum size is rarely reached in the wild

-Flowers, fruits, and leaves

What are the characteristics of indeterminate growth?

-Growth only limited by environmental factors

-Usually can regrow and heal

-Can grow all throughout life

-Stems and roots

The cell theory states that

1. All plants and animals are made of cells

2. Cells are the basic unit of life

3. All cells come from previous cells by reproduction

What are the four components shared by all cells?

- DNA

- Plasma Membrane

- Cytoplasm

- Ribosomes

What is the plasma membrane?

a phospholipid bilayer with embedded proteins

What is the function of the plasma membrane?

Serves as a barrier between the cell and its environment. It also conducts the passage of organic molecules, water, oxygen, ions, and waste (CO2 and ammonia)

What is the cytoplasm?

The region between the plasma membrane and the nuclear envelope. It consists of organelles suspended in cytosol and the cytoskeleton

What is the function of the cytoplasm?

Provides structure to the cell

What is the function of DNA/ the nucleus?

- Directly synthesizes the production of ribosomes and proteins

- Stores chromatin (DNA + protein) and the nucleolus (where ribosomes are made)

When is DNA visible as chromosomes?

During cellular replication

When is DNA visible as chromatin?

During cellular growth and maintenance, when proteins attach to chromosomes

What are ribosomes?

- Structures responsible for protein synthesis

- They are NOT organelles

- They can be free or embedded in the endoplasmic reticulum

What are the unique characteristics of eukaryotic cells?

- Endomembrane system

- Endoplasmic reticulum

- Golgi apparatus

- Mitochondria

What is the endoplasmic reticulum?

A series of interconnected sacs and tubules that modify proteins and synthesize lipids

What is the golgi apparatus?

Flattened membranes that receive proteins and lipids from the endoplasmic reticulum and packages them and transports them

What is the mitochondria?

- Site of cellular respiration

- contains its own DNA and ribosomes

What are the unique structures of plant cells?

- Cell wall

- Central vacuole

- Plastids such as chloroplast

What is the central vacuole?

- Stores and regulates water through osmosis

- Contains water, ions, nutrients, and waste

- Is surrounded by the tonoplast

What is a chloroplast?

- Site of photosynthesis

- Contains chlorophyll and other pigments

- Contains its own DNA and ribosomes

- Pigments are stored in thylakoids which stack to make grana

What are the other plastids?

- Chromoplast (yellow/ orange)

- Amyloplast (stores starch)

What is the middle lamella?

Thin pectin layer that binds adjacent cell walls

What is the primary cell wall?

- Occurs on all plant cells

- Made of cellulose microfibrils

- Thin and flexible

- Some plants contain only this wall

What is the secondary cell wall?

- Made up of layers deposited inner to primary cell wall

- Made of lignin and cellulose for sturdiness

- Occurs as cells reach maturity

- Its growth pushes cell membrane further in, possibly leading to cell death

What determines the direction of cell growth?

Orientation of cellulose microfibrils

What are plasmodesmata?

Pores which allow communication between cells

All plant tissue originate from what?

Meristematic tissue

What does it mean for plant tissue to be totipotent?

The tissue can regenerate the entire plant

What are meristems?

Regions of continuous cell division and growth

What are the three types of meristems?

Apical, lateral, and intercalary (grasses only)

What are apical meristems?

- Regions of cell division at the end of stems (shoot apical meristems) and roots (root apical meristem)

- Produce three types of primary meristematic tissues

What are the three types of primary meristematic tissue produced by the apical meristem?

Protoderm, ground meristem, and procambium

What is the protoderm?

Gives rise to epidermis

Function of ground meristem?

Gives rise to ground tissue (photosynthetic, storage, support)

Function of the procambium?

gives rise to vascular tissue (transport)

What are lateral meristems?

- Also called secondary meristems

- Responsible for secondary growth (girth)

- Located in two regions

What are the two regions of lateral meristems?

Vascular cambium and cork cambium

What is the vascular cambium and what does it do?

- Arises from the procambium

- Gives rise to vascular tissue

What is the cork cambium and what does it do?

- Arises from pericycle and the cortex

- Produces periderm (secondary dermal tissue)

What are the typical components of a seed?

- Seed coat

- Embryo (new plant)

- Endosperm or cotyledon (nutrients)

First phase of eudicot embryogenesis?

The seed contains the endosperm (triploid) and the zygote (diploid)

Second phase of eudicot embryogenesis?

The zygote divides to form the proembryo which is attached tp the micropyle by the suspensor. The endosperm begins to divide

Third phase of eudicot embryogenesis

The embryo proper is in globular stage, a spherical mass of cells

Fourth phase of eudicot embryogenesis

Embryo proper is in the heart stage. The heart stage gives rise to the cotyledons

Fifth phase of eudicot embryogenesis

Embryo proper is in torpedo stage- the shoot apical meristem is between the cotyledon and the root apical meristem is anchored to the suspensor

Sixth phase of eudicot embryogenesis

The mature embryo includes the radicle, the hypocotyl, the epicotyl, and the ovule has developed into the seed coat

What stage is missing in monocot embryogenesis?

The heart stage

What are the two parts of the seed coat?

Testa (outside) and tegmen (inside)

Hilum

Where the seed attaches to the endocarp (inner layer of fruit)

Microphyle

Where pollen tubes entered (seed coat)

Embryo axis from top to bottom

- The plume

- The radicle

What is the plume?

Young shoot containing the shoot apical meristem and the leaf primordia (developing leaves)

What is the radicle?

embryonic root

What is the hypocotyl?

the region between the cotyledon attachment point and the radicle

What is the epicotyl?

the region between the cotyledon attachment point and the shoot tip

Unique characteristics of monocot seeds?

- Test and tegmen are fused

- Fruits have only one seed and the pericarp

- Root tip is protected by the coleorhiza (sheath like structure)

- Plume is protected by the coleoptile

Scutellum

the name of the single cotyledon. Has a vascular connections with the rest of the embryo

Aleurone

outer layer of endosperm which secretes enzymes during germination

Methods of seed dispersal

wind, animal, water, self-dispersal

Physical dormancy

type of seed coat barrier that uses impermeability to water and oxygen

Chemical dormancy

type of seed coat barrier that uses compounds to inhibit germination

Physiological dormancy

type of embryonic barrier that requires environmental conditions to complete maturation

Endodormancy

type of embryonic barrier in which internal biochemical processes must be met before germination can begin

Ecodormancy

type of embryonic barrier in which external factors are not optimal for germination

Common germination requirements

- sufficient light

- proper temperature

- oxygen

- water

epigeous germination

hypocotyl elongates, cotyledon extends above ground

Hypogenous Germination

epicotyl elongates and the cotyledon remain underground

Only type of germination that does not form a hook

Hypogeous monocots

What occurs when the coleoptile is exposed to sun light?

It stops growing and is pierced by the plume

Two types of roots

Tap root system

Fibrous root system

Root functions

Anchorage, support, absorption, nutrient storage

Root cap

protects apical meristem

What is behind/ above the apical meristem?

the area of elongation

What is above the area of elongation?

The area of maturation where epidermal cells form extensions called root hairs, improving absorption

From what does the shoot system originate?

The plume of the embryo

Functions of a stem

Support

Conduction- moves water up from roots and photosynthesis products down from leaves

Photosynthesis- in green stems

Food storage- mainly starches

What are stem nodes?

Points of attachment for leaves

Internode region of the stem

Area between nodes that elongates to ensure separation of leaves

Axillary bud

Found between the stem and the leaf

Can give rise to a new shoot with its own apical meristem

Secondary meristem consists of...

the vascular cambium and the cork cambium

The vascular cambium divides into the...

secondary xylem(inside) and the secondary phloem (outside)

The cork cambium produces

Periderm tissue

The protoderm produces...

epidermis

The shoot apical meristem produces...

Procambium

Ground Meristem

Protoderm

The procambium produces the...

Primary xylem

Primary phloem

Fascicular cambium

The ground meristem produces

pith and cortex

When does the periderm replace the epidermis

In shoots at the end of the first year of growth

lenticels

elevated regions with large intercellular space that allows gas exchange in shoots

rhytidome

old layers of periderm that die and are pushed out, producing the texture of bark

Inner bark includes the...

secondary phloem

cortex

phelloderm

outer bark includes the...

cork cambium

periderm

cork

wood consists of the...

original pith

primary xylem

secondary xylem

What is heartwood?

oldest and innermost layer of secondary xylem. It is darker in color

Tylosevessel elements prevent water flow

What is sapwood?

Water conducting xylem in the periphery of heartwood and is lighter in color

Lateral (axial) buds types

Monopodial and sympodial

Monopodial type of branching

buds do not degrade and all shoots continue to grow

Sympodial type of branching

terminal buds degrade and lateral buds closest to the apex become the new terminal shoot

Blade (lamina) of leaf

flat, usually widest part