Bio Lecture Exam 3

Shoots

Aboveground part, generate sugar and transport it to other parts. Flowering/reproductive structures, vegetative structures (non-reproductive)

Stem

middle structure, supports (physical and aid) leaves

Leaf

do photosynthesis/make carbohydrates

Node

where leaves are attached to the stem

Internode

the parts of the stem without leaf attachment (b/w the nodes)

Terminal bud (apical)

the growing end of the stem (at the very top)

Lateral bud (axillary)

an undeveloped shoot/stem that is in the node. This bud may develop into new stem, leaf, or flower, or remain dormant

Roots

belowground part, anchors plant to the ground and absorb water and minerals, transport it to other parts

Primary growth

focus on elongating shoots and roots (all plants do this), herbaceous plants

Secondary growth

focus on thickening stems and roots (only some do this), woody plants

Ground tissue

bulk of interior of stems, leaves, and roots. Form the majority of the plant body. Several specialized cell types within the system perform photosynthesis and cellular respiration, store nutrients, produce elastic and inelastic support. Some cells secrete hormones, do gas exchange, and repair damage.

Dermal tissue

surface of stems, leaves, and roots. Cover the exterior surface of the plant. Produce the epidermis cells (outer layer) which secrete the cuticle layer. Embedded in the epidermis are the stomata

Vascular tissue

Xylem and phloem tissue found in stems, leaves, and roots. Transportation of water, minerals, carbohydrates, hormones, and other material

Vascular bundle

strand of tissue containing xylem, phloem, and lignin

Xylem

Transports water mainly

Phloem

transports carbohydrates mainly

Lignin

tough molecules that supports xylem structure, allowing for big plants

Monocot stem

vascular bundles are less organized. Bundles have 2 main xylem vessels surrounded by several phloem vessels and fibers

Eudicot stem

vascular bundles are organized in a circle. Bundles have ~equal number of xylem and phloem vessels, xylem and phloem not as organized. Also have pith and cortex

Pith and cortex

Store starch and water

Monocot leaf

have parallel veins, have stomata on the top and the bottom side of the leaves, have one type of mesophyll cells (uniform)

Eudicot leaf

have netted veins, have stomata only on the bottom side of leaves, have two types of mesophyll cells (columnar and loosely irregular)

Monocot roots

organized roots, fibrous root system

Fibrous root system

widespread but shallow network of thin roots

Eudicot roots

have vascular bundles centered, have taproot root system

Taproot root system

one primary root with lateral root branches, deep growth

Root cap

protective layer of cells at the tip of each root branch. Continually damaged and replaced, and can secrete fluid to help push through soil

Root hair

extensions of epidermal cells that maximize surface area for water and nutrient absorption

Modular growth

growth occurs through the formation of new units (or modules). In plants, a module is an internode and a node

Determinate growth

Some plants stop growing once they reach maturity

Indeterminate growth

can grow indefinitely by utilizing modular growth

Meristems

regions within plants that undergo mitosis to generate new tissue (analogous to animal stem cells)

Apical meristems

patches of actively dividing cells near the tips of roots and shoots (dormant apical meristems in the later/axillary buds)

Lateral meristems

an internal cylinder of dividing cells along the length of roots and stems. Thickens roots and stems (secondary growth seen in woody plants

Intercalary meristems

between the nodes on the stem (in some monocots). Allows for regrowth of a module after damage (like cutting grass)

Primary growth in shoots

shoot apical meristem cells divide, generating new tissue, New leaves originate on the sides. Remnants remain in the lateral buds for future growth

Primary growth in roots

the root apical meristem is located behind the root cap and makes new cells as the three tissue types. New tissue cells elongate by absorbing water (in vacuole). mature by differentiating into the specific cell type (ground, dermal, vascular)

Roots divided into 3 “zones”

Cell division, elongation, maturation

Zone of cell division

root apical meristems and root cap

Zone of elongation

new cells, absorb H2O

Zone of maturation

mature cells (ground, derma, and vascular tissue)

Hormone

A messenger molecule produced in an organism transported to a target tissue to stimulate an action (ex. Insulin), are (generally) produced and used when they are needed. Not always present and always signaling

Auxin

stimulate elongation of cells in stems and fruits, suppress growth of lateral buds, control plant movements (controls tropisms) **primary hormone

Cytokinin

stimulates cell division at all stages of life, primarily in roots, seeds, fruits, and young leaves, help slow aging

Gibberellin

stimulate cell division and elongation in roots and shoots and trigger seed germination

Ethylene

stimulates fruit ripening, and flower, leaf, and fruit shedding

Abscisic acid

inhibit shoot growth and maintains bud dormancy, induces and maintains seed dormancy, induces closing of stomata (stress response hormone)

4 plant responses to light

Photoreceptors, phototropism, circadian rhythms, flowering photoperiod

Photoreceptors

Molecules that detect light wavelengths, they absorb light and trigger some action by the plant in response to light absorption (often working with hormones). Some animals also have them (rods and cones)

Phototropism

Directional growth toward (positive) or away (negative) from light

Phototropism step 1

Auxin migrates to side of the plant NOT receiving sunlight and enters cells

Phototropism step 2

Auxin causes membrane proteins to open, allowing hydrogen ions to exit the cell and enter the cell wall

Phototropism step 3

H+ ions enter, loosening the cell wall

Phototropism step 4

With more space available, the vacuole takes in more water, stretching the cell

Gravitropism

directional growth in response to gravity, shoots always grow up, roots always go down

Statoliths

organelles within root cap cells that “detect gravity”

Thigmotropism

Plants move in response to stress. Plants grow shorter when touched often by animals, some plants grip structures to grow vertically, others “close” their leaves

Annual plants

short life spans, die after one growing season

Biennial plants

grow vegetative parts during first growing season, enter dormancy, reproduce in second growing season and then die

Perennial plants

live for multiple growing seasons

Deciduous trees

perennial plants that enter dormancy every winter, lose their leaves in the fall

Evergreen plants

perennial plants that do not enter dormancy every winter

Change deciduous trees undergo in fall step 1

Enzymes digest photosynthetic pigments (chlorophyll, carotenoids) and nitrogen and phosphorous move from leaves to stems and roots

Change deciduous trees undergo in fall step 2

Once leaves are nutrient-depleted, they can be shed (process called abscission)

Change deciduous trees undergo in fall step 3

Ethylene hormone stimulates the digestion of plants matter at the abscission zone

Why do deciduous trees undergo change

Water is difficult to get/keep (dry winter increases water loss, frozen water in soil cannot be absorbed by roots), sunlight is less available (shorter days means less sunlight per day)

Epithelial function

cover interior and exterior surfaces or organs; protection, secretion, absorption

Epithelial selected locations

In glands; inner linings of blood vessels, lungs, kidney tubules, digestive tract; skin

Epithelial embryonic origin

endoderm, ectoderm, or mesoderm

Connective

Have a large amount of extracellular matrix and/or interstitial fluid

Connective function

support, adhesion, insulation, attachment, transportation

Connective selected locations

Tendons, ligaments, cartilage, bone, blood, fat deposits

Connective embryonic origin

Mesoderm

Interstitial fluid

the liquid form of the extracellular matrix

Muscle function

Movement

Muscle selected location

Skeletal muscle, heart, arteries, digestive tract

Muscle embryonic origin

Mesoderm

Nervous function

Rapid communication among cells

Nervous selected location

Brain, spinal cord, nerves

Nervous embryonic origin

Ectoderm

General structure of all epithelial

single or multiple layer of flattened, cube-shaped, or columnar cells

Layers

simple (single layer), stratified (multiple layers)

Shapes

squamous (flat), cuboidal (cubed), columnar (tall and thin)

Simple squamous

allows substances to pass through it via diffusion and osmosis. Blood vessels, lungs, kidneys

Simple cuboidal

secretes and absorbs substances. Endocrine glands and kidneys

Simple columnar

secretes and absorbs substances in airways and digestive tract, sweeps egg/embryo along the uterine tube. Digestive tract airways (bronchi), uterine tubes

Stratified squamous

protection from abrasion, water loss, and infection. Outer layer of skin, lining of most body openings

Stratified cuboidal

moves/conveys sweat, secretes hormones. Sweat glands, ovaries

Pseudostratified columnar

secretes and propels mucus. Upper airways. Not really stratified, only difference b/w simple is the location of the nuclei

Connective tissue structure

Cells scattered in prominent extracellular matrix

Loose connective tissue

Cells in loose matrix of elastin and collagen fibers. Holds organs in place, attachment for epithelial tissue. Under skin, b/w organs

Dense connective tissue

Cells in dense matrix of elastin and collagen fibers. Connect muscle to bone and bone to bone. Tendons and ligaments

Adipose tissue

Fat cells in very little matrix, stores fat for energy and isolation. Beneath skin, b/w muscles, around heart and joints

Blood

Red blood cells, white blood cells, platelets, matrix of plasma. Transports gases, nutrients, wastes, hormones. In blood vessels and chambers of the heart

Cartilage

Cells in matrix of collagen fibers. Flexible support. Ears, joints, bone ends, airways

Bone tissue

Bone cells in matrix of collagen and minerals. Firm support. Skeleton