Total Biology 186 Final

Dendrochronology

The process of counting tree rings to determine the age of a tree

Short distance transport

water and solutes move through three pathways:

1. Apoplastic, 2. Symplastic and/or 3. Transmembrane

Apoplastic route

via the cell walls and extracellular spaces

Easy

Pros and cons of a plant on land

Pros:

1. Light not limiting

2. Oxygen and carb on dioxide more plentiful

Cons:

1. Gravity

2. Water less plentiful

3. Water/nutrients at different location than gases

4. Dispersal of gametes

5. Different stressers: UV, temp flux

Adaptions to life on land: maintain moisture

- water transport systems: transport from soil to leaves

- cuticle/stomata: avoid/regulate water loss

- pollen grains/ seeds: resistant to desiccation

Adaptions to life on land: reproduction and dispersal

- animal pollination/fruits

- more targeted pollen/seeds dispersal

Adaptions to life on land: obtain resources

- larger leaves to increase photosynthesis

- larger plants

- shoot and root system

- transport systems: xylem and phloem

Adaption to life on land: support plant body against gravity

- thicker cell walls and lignin

Adaption to life on land: protection from stresses

- secondary metabolites

Which came first- increased photosynthetic structures or increased water transport infrastructure?

Increased water transport infrastructure

Why are mosses not growing tall like trees?

Because mosses lack vascular tissues and lignin

Primary growth via

Apical meristems

Secondary growth via

Lateral meristems: vascular and cork cambium

Primary growth

Grow tall

Secondary growth

Grow thick

Secondary xylem

Wood

symplastic route

through the cytosol

Easy

transmembrane route

out of one cell, across a cell wall, and into another cell

Not so easy!

Aquaporins

Bidirectional channel that allow only water molecules to pass through

Osmosis

Free water will move into cells with a high solute concentratiob

Water potential ψ

Potential energy of water under given conditions compared to pure water under reference conditions

Measures in MPa

Water pressure equation

ψ = ψs + ψp

ψs is always

negative

Solutes in plant cells

Ions and sugars

pressure potential (ΨP)

Physical pressure on a solution

Cohesion-adhesion theory

molecules pull each other along

Cavitation

Formation of a cavity or hole

Percent of water loss through stoma

95%

Stomata opening and closing

Potassium ions pumped into cell, water follows, guard cells balloon-> stomata open

Potassium ions pumped out of cell, water follows, guard cells shrink-> stomata closed

When are stomata open?

During the day, allows gases to move into and out of the plant, plenty of moisture in the air and soil

when are stomata closed?

During the night

Factors effecting stomata open/closed

Balance CO2 uptake and water loss,

Driven by light, co2 concentration, circadian rhythm

what organisms preform photosynthesis

all photoautotrophic

outcomes of photosy

- produces almost all organic material required by consumers

- produces oxygen required by animal life forms

- 160 billion t of carbohydrate/yr

where is photosynthesis preformed (land plants)

in green plant tissues

in chloroplasts

photosynthesis equation

6H2O + 6CO2 + sun -> C6H12O6 + 6O2

redox reaction: H2O is oxidized, CO2 is reduced

energy stored in:

chemical bonds within carbohydrates

the three steps of photosynthesis

1. photochemistry in thylakoids (light reactions)

2. electron transfer and production of ATP (light reaction)

3. incorporation of CO2 into carbohydrate and production of O2 (Calvin cycle/dark reaction) in stoma

when lights meet matter it can be

reflected, transmitted or absorbed

three classes of light-absorbing compounds: pigments

i. chlorophylls (chl): chl a and chl b

ii. carotenoids

iii. phycobilins (only found in red algae and cyanobacteria): chl a and chl c but no chl b

what colour of light do chlorophyl absorb

approx 70% if the red and blue wavelength light

(does NOT absorb green)

absorbance spectrum

absorbance response of a pigment exposed to a series of wavelengths of light

action spectrum

physiological response of the organism to specific wavelengths

porphyrin ring

light-absorbing "head" of molecule with a magnesium atom at the centre

light harvesting complexes

protein structures embedded in the thylakoid membrane

chl a and chl b carotenoids transfer energy (not electrons)

connected to "reaction centres"

reaction centres

connected to "light harvesting complexes"

transfer of electrons to primary electron acceptor

photosystem =

light harvesting complexes + reaction centre

steps to exploit excitation energy in photosystems

1. light excited pigment in PSII -> excited e- -> as this e- falls to ground state another e- in nearby pigment is excited -> finally e- in pigment P680 is excited

2. transfer of e- from chlorophyll a pair (P680) to primary electron acceptor (now P680+ missing e-):

3. e- hole in P680+ must be filled: P680+ is the strongest biological oxidizing agent known -> pulls e- from water

the two photosystems in the thylakoid membrane:

PS I with P700 and PS II with P680

how are electrons used to generate energy rich compounds

ATP synthesis and NADPH synthesis

Light reactions (big picture)

solar power (photons) to generate ATP and NADPH for carbohydrate producing reactions in the Calvin cycle

what is dark reactions in the stoma need more ATP than NADPH?

e- recycling: Cyclic electron flow w/in PS I

ATP production

conversion of light energy to H+ gradient

-> H+ (pH) gradient used for ATP synthesis

what happens when the lights go out?

all light reactions stop (photochem, e- transport, splitting of water / O2 production, H+ gradient generation)

CO2 absorption and super production continues (as long as substrates are available): dark reaction or Calvin cycle

steps of the calvin cycle:

1. carbon fixation

2. reduction

3. regeneration of CO2 acceptor

RuBisCO problem and solution

problem: plants changed the atmospheric gas composition

-> [O2} went from 2% to 20%, RuBisCO became increasingly inefficient (with O2, produces useless 2C compound)

Solution: C4 plants

G3P

Glycerol-3-Phosphate

the "starter for all biological organic matter"

physiology

the study of the functions of organisms

anatomy

the study of the structure of organisms

tissue

integrated group of cells with a common structure and function

four main categories of tissue

1. epithelial tissue

2. connective tissue

3. muscle tissue

4. nervous tissue

epithelial tissue definition and function

sheet of tightly packed cells covering the body and lining organs and cavities: polarized

functions: barrier, exchange surface, absorption or secretion

What are the types of epithelial tissue based on the number of layers?

Simple - single layer of cells

Stratified - multiple tiers of cells

Pseudostratified - single layer that appears to be stratified

What are the shapes of cells in epithelial tissue?

Cuboidal (like dice)

Columnar (like bricks)

Squamous (flat like tiles)

connective tissue function

to bind and support other tissue

connective tissue cells

sparse population

connective tissue matrix

web of fibres embedded in uniform foundation

the three fibres

collagenous

elastic

reticular

What are the characteristics of loose connective tissue?

Contains all three types of fibers, loosely woven, binds epithelia to tissues, and serves as a packing material. Cells include fibroblasts and macrophages.

Describe fibrous connective tissue.

Consists of collagenous fibers that are dense and form parallel fiber bundles for non-elastic strength.

What are the functions of adipose tissue?

Stores fat, pads and insulates the body. It is a type of loose connective tissue.

What is the role of cartilage in the body?

Provides flexible support due to an abundance of collagenous fibers in a rubbery matrix. Contains chondrocytes.

Explain the characteristics of bone tissue.

Makes up the skeleton, supporting the body of most vertebrates. It is mineralized connective tissue with cells such as osteoblasts and osteocytes.

What are the components of blood?

Contains an extensive extracellular matrix called plasma. Cells include erythrocytes, leukocytes, and platelets.

what are the 6 types of tissue

1. loose connective tissue

2. fibrous connective tissue

3. adipose tissue

4. cartilage

5. bone

6. blood

muscle tissue function

muscle fibres contract when stimulated by nerve impulses

what is the most abundant tissue in most animals?

muscle tissue

3 multiple choice options

What are the characteristics of striated muscle tissue?

Responsible for voluntary movements, e.g., skeletal muscle.

What are the characteristics of smooth muscle tissue?

Lacks striations, e.g., found in the intestine.

What are the characteristics of cardiac muscle tissue?

Striated, cells are branched, and forms the contractile wall of the heart.

the three types of muscle tissue

striated, smooth, cardiac

nervous tissue

sense stimuli and transmit signals from one part of the animal to another

nervous tissue cells

neurons and glial cells

neurons function

functional units of nervous tissue, transmit nerve impulses

glia function

support neurons metabolically, structurally and functionally

organs

specialized centres of body function composed of several different types of tissue

organ systems

group of organs that work together in preforming vital body functions

Homeostasis

the maintenance of a relatively stable internal environment despite changing external conditions

homeostatic mechanisms maintain internal conditions w/in ...

a relatively small range of values (not a constant value)

regulator

use mechanisms of homeostasis to moderate internal change in the face of external fluctuations

do endotherms thermoregulate?

yes

conformer

allows some conditions w/in its body to vary w/ certain external changes

osmoregulation

management of the body's water content and solute composition

osmosis

diffusion of water across a selectively permeable membrane

molarity

moles of solutes/volume (L)

osmolarit

osmoles of solute particles/volume (L)

1 osmole

1 mole of osmotically active particles

osmolarity

osmoles of solute / kg

isoosmotic with medium

body fluids = same osmotic pressure as medium

hyperosmotic

osmotic concentration is higher than medium