Bio Test 3: Diseases and Photosynthesis

Rainbow

Caused by reflection, refraction, and dispersion of light in water droplets

Rods

black & white, low light (night vision)

Cones

color vision (red, blue, green)

More rods

better night vision

Some species have tetrachromatic vision

(4 cone types)

~25% of humans may have a 4th cone which means

better color perception

Process where plants use light energy

chemical energy

Equation

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Photosynthesis Occurs in

chloroplasts

Photosynthesis Uses

chlorophyll (a & b)

Importance

Stores energy in glucose, Produces oxygen, Builds plant structure (cellulose), Supports ecosystems (food source)

Pigments

substances that absorb light

Main pigments

Chlorophyll a & b

Accessory pigments

Carotenoids and Phycobilins

Accessory pigments can

Expand light absorption range and Increase efficiency

Why plants look green

Green light is reflected (not absorbed)

Anthocyanins

red/purple colors in leaves

Engelmann Experiment

Used prism + algae + bacteria

Bacteria clustered where most O₂ was produced Showed

Red & blue light drive photosynthesis most

chloroplast Structures

Outer membrane, Inner membrane, Thylakoids (site of light reactions)

1. Light-Dependent Reactions (Thylakoid) Inputs

Light, H₂O, ADP, NADP⁺

1. Light-Dependent Reactions (Thylakoid) Outputs

ATP, NADPH, O₂

Light dependent reaction step 1

Light excites electrons in Photosystem II

Light dependent reaction step 2

Water splits → replaces electrons + releases O₂

Light dependent reaction step 3

Electron Transport Chain (ETC) pumps H⁺

Light dependent reaction step 4

Photosystem I re-excites electrons

Light dependent reaction step 5

NADPH formed

Light dependent reaction step 6

H⁺ gradient → ATP via chemiosmosis

2. Calvin Cycle (Stroma) Inputs

CO₂, ATP, NADPH

2. Calvin Cycle (Stroma) Outputs

Glucose

Light-independent (but depends on light products) Occurs

in stroma

Light-independent (but depends on light products) Fixes

carbon into sugar

Light & Pigment Interaction

Light excites electrons in pigments

Energy used to make

ATP & NADPH

Photosynthesis stores

energy

C3 Plants

Most plants

C3 plants Use

RuBisCO

Problem with C3

photorespiration (wastes energy)

C4 Plants Examples

corn, sugarcane, sorghum

C4 plants Use

PEPC enzyme

C4 plants are Better in

Hot, dry environments. and High light

C4 plants Reduce

photorespiration

RuBisCO reacts with

O₂ instead of CO₂

photorespiration produces

toxic compound and Wastes energy

Light is required for photosynthesis, so it

stops in dark

Plants respiration

day & night

Chloroplasts make ATP for

photosynthesis only

Mitochondria make ATP for

the cell

If H⁺ gradient is disrupted then

less ATP → lower fitness

Without light

no O₂ production

Without NADPH

no sugar production

Calvin cycle stops when

ATP/NADPH run out

Most plant mass comes from

CO₂ (air)

Emerging Disease

A disease that is new to a particular population.

Epidemic

A rapid spread or growth of disease in a population.

Population Density

The number of individuals in a given area, influencing disease spread.

Density-dependent Factors

Mortality risks related to population density, such as contagious diseases.

Density-independent Factors

Mortality risks unrelated to population density, such as natural disasters.

Birth Rate (b)

The number of individuals born per individual per unit time.

Death Rate (d)

The number of individuals that die per individual per unit time.

Population Growth Rate (r)

The difference between the birth rate and the death rate.

Growth Increment (G)

The number of individuals added to or lost from a population in one unit of time.

Carrying Capacity (K)

The maximum number of individuals of any species that can be indefinitely supported in a given area.

Logistic Growth

A model of population growth that starts exponentially but slows as the population approaches the carrying capacity.

Innate Immunity

The defense system with which you are born, protecting against all antigens.

Adaptive Immunity

A specialized immune response that remembers pathogens for quicker responses in the future.

Antigen

A substance that provokes an immune response, often leading to the production of antibodies.

Antibodies

Proteins produced by plasma cells that bind to specific antigens to help eliminate them.

Vaccines

Substances that contain antigens and provoke an immune response to provide immunity against diseases.

Why does sexual reproduction produce more

genetic variability in a population than asexual

reproduction?

In addition to the variation that meiosis creates, fertilization

mixes parental genetics.

In nerve impulse transmissions, the neuron sending

the message across the synapse is called the

presynaptic cell

The type of reproductive isolation in which two

populations live in the same habitat but remain isolated

from one another due to one being active during the

daytime only and the other being active only during

the night is

temporal isolation

The part of the neuron that is a single, long extension

with a branching tip, that conducts impulses to a muscle

or another neuron is the

axon

Meiosis is a process used for

production of

gametes

A neuron fires when Na+ ions

move down their concentration gradient by the process of

facilitated diffusion

r = population growth rate

r = birth rate – death rate = b - d

Can r be negative?

Yes, if there are more deaths than births

G = Growth increment

G = population growth rate (r) * population size (N)

Pop. size next year

= Current pop. size + G

If the DNA in a cell consists of 20% A, it will be

_________ G.

30%

A seedling plant has a section of the stem tip

that contains large numbers of cells

undergoing mitosis for the purpose of

growth in height of the plant

After a plant egg cell is fertilized by pollen it would

contain ____ number of chromosomes as contained

within a diploid leaf cell from that same flowering

plant

an equal

If you cross two pea plants, one with green peas and

the other with yellow peas, you find all of the

offspring have yellow peas. You conclude the yellow

parent was

homozygous for the dominant allele

A desert plant called Kalanchoe can reproduce, either with

sexual reproduction through flowers, or asexually by budding

off miniature leaf and root clusters from its leaves. When buds

are produced, they land on the ground, take root, and grow,

genetically identical to the original. If budding is used for

several years, a large area may be covered with these

descendents from the same original plant. The resulting

population of plants will

not be well suited to a changing environment

Autotroph

organism that produces organic molecules by acquiring carbon from inorganic sources; a primary producer

Heterotroph

organism that obtains carbon and energy by eating another organism; a consumer

Photosynthesis

biochemical reactions that enable organisms to harness sunlight energy to manufacture organic molecules

ATP (adenosine triphosphate)

a molecule whose high-energy phosphate bonds power many biological processes

electromagnetic spectrum

electromagnetic spectrum

photon

a packet of light or other electromagnetic radiation

wavelength

the distance a photon moves during a complete vibration

chlorophyll a

green pigment that plants, algae, and cyanobacteria use to harness the energy in sunlight

accessory pigment

photosynthetic pigment other than chlorophyll a that extends the range of light wavelengths useful in photosynthesis

stoma (pl. stomata)

pore in a plant’s epidermis through which gases are exchanged with the atmosphere

mesophyll

photosynthetic tissue in a leaf’s interior

stroma

the fluid inner region of the chloroplast

grana

a stack of flattened thylakoid disks in a chloroplast

thylakoid

pancake-shaped structure that makes up the inner membrane of a chloroplast

photosystem

cluster of pigment molecules and proteins in a chloroplast’s thylakoid membrane

antenna pigment

photosynthetic pigment that passes photon energy to the reaction center of a photosystem