Final Flashcards
(149 cards)
1
Q
Photosynthesis
A
-Photosynthesis allows plants to transform solar energy into biochemical energy.
-The stored biochemical energy converts CO₂ and H₂O into sugars.
-Non-photosynthetic organisms depend on photosynthesis by consuming biomass(organic material, ex eating plants ettc)
-(C₆H₁₂O₆): 6CO₂ + 12H₂O + light energy → C₆H₁₂O₆ + 6O₂ + 6H₂O
2
Q
Photosynthesis and respiration
are
A
inter-dependent processes
3
Q
all organisms obtain stored energy through
A
respiration to perform metabolic activities
4
Q
Respiration occurs in
A
Respiration occurs in the mitochondria, where living organisms break down sugars (like glucose) to release energy. In the presence of oxygen, stored energy from glucose and other organic molecules is converted into ATP, the cell’s energy currency.
5
Q
ATP
A
is the energy currency
of the cell
6
Q
Photosynthetically active light (visible and leaves)
A
-40% of solar energy received
on earth is in form of visible light
-Leaves absorb 80% of visible
light reaching them
7
Q
Chlorophyll absorbs light
A
-in the blue (430 nm) and red (680 nm) regions of the visible! spectrum (400-700 nm) green light is reflected.
-In some cases, removing the chlorophyll may increase green reflection
8
Q
Chlorophyll a (C55H72MgN4O5)
A
is the pigment directly involved in the light reactions
9
Q
Chlorophyll b (C55H70MgN4O6)
A
transfers absorbed light energy to chlorophyll a but does not directly
take part in the light reactions (chlorophyll b is an accessory pigment. Makes it
possible for photosynthesis to occur over broader spectrum of light)
10
Q
photosynthetic pigment
A
-carotenoids: reflect yellow and orange, also accessory pigment.
-phycobilins: blue or red, in cyanobacteria and red algae
and other types of chlorophyll
11
Q
Accessary Pigments
A
are not visible until chlorophyll
a breaks down (fall colours)
12
Q
Evergreen leaves have
A
the lowest photosynthetic rate, lowest nitrogen and longest living
13
Q
Cavitation
A
Cavitation in plants is when air bubbles form and block water flow in the xylem due to pressure changes.Losing leaves reduces the probability of cavitation (remember: evergreens are more cavitation resistant because of their xylem which is reinforced with extra woody material)
14
Q
Deciduous plants have higher..
A
-rates of photosynthesis per unit leaf mass
* higher ability to perform photosynthesis
(due to higher levels of nitrogen, thinner leaf cross sections, higher rates of transpiration)
* Less water loss during winter
15
Q
What happens when pigments absorb light
A
energy
levels of electrons are raised.
16
Q
The two series of reactions in photosynthesis are:
A
Light-dependent reactions:
Take place in the thylakoid membranes. Use light energy to produce ATP and NADPH.
Release oxygen as a byproduct from water.
Light-independent reactions (Calvin cycle): Take place in the stroma.
Use ATP and NADPH from the light reactions to fix carbon dioxide into glucose.
17
Q
Light-dependent Reactions
A
-Occur in the thylakoid membranes of chloroplasts
-Are the “photo” part of photo- synthesis because they capture light energy
-Water molecules split apart, releasing electrons, hydrogen ions and oxygen
-Electrons pass along electron transport system.
-ATP produced and NADP is reduced, forming NADPH
(these products are used in light- independent reactions)
18
Q
Light-independent Reactions
A
-Occur in the stroma of chloroplasts
-Are the “synthesis” part of photosynthesis
-Use ATP and NADPH to form sugars
-Calvin cycle
-Carbon dioxide combines with RuBP (ribulose bisphosphate) and are then converted to sugars (glucose).
19
Q
photosystems
A
Pigment molecules in the thylakoid
membranes that are grouped as separate photosynthetic unit (Photosystem I and II)
20
Q
Each photosystem consists of an
assembly
A
of 250-400 pigment molecules
(Events of photosystem II come before those of photosystem I).
21
Q
Photosystem I (PSI)
A
-200+ chlorophyll a, small amount of chlorophyll b, carotenoid, and reaction-center molecule (P700)
P700 - Only one that actually can use light energy
- Remaining pigments = antenna pigments (gather and pass light
energy to reaction center)
- Iron-sulfur proteins - Primary electron acceptors, first to receive
electrons from P700
-
22
Q
Photosystem II (PSII)
A
-mostly chlorophyll a, β-carotene,
little chlorophyll b, and reaction-center molecule (P680)
- Pheophytin (Pheo) - Primary electron acceptor
23
Q
Light Reaction Centre
A
Proteins:
● Light harvesting (LHCII)
● Reaction Centers (PSI & PSII)
● Proteins with 2 electron
transport chains (Cytochrome) from psII to psI
● ATP Synthase Complex
24
Q
production of atp and nadph
A
Light-dependent reactions use energized electrons from PSII to produce ATP and use re-
energized electrons from PSI to produce NADPH
25
in photosynthesis, the efficiency of conversion of light energy into chemical energy is
about 27%, while The overall energy conversion into biomass is
approximately 4-6%. Solar panels convert light into electricity at a, photosynthetic efficiency of about 10-20%. Loss in efficiency due mainly to photorespiration
26
Photoinhibition
a decrease in photosynthetic
capacity associated with too much light exposure(meaning that it can still perform photosynthesis, but not as effectively as it would under normal light conditions.)
27
Photooxidation
results from the bleaching of
chlorophyll by light (plays a role in leaves turning colors) This can significantly reduce or even halt photosynthesis if enough chlorophyll is damaged.
28
what fuels the calvin cycle (2nd part of photosynthesis)
ATP & NADPH, which makes simple sugar phosphates. Also called the dark reaction. occurs in the stroma
29
Calvin-Benson-Bassham Cycle
Named after: Melvin Calvin, Andrew Benson, and James Bassham (1953)
Determined the pathway plants use to convert CO₂ into sugars.
Nobel Prize: Melvin Calvin won in 1961 for his discovery.
Experiment: Used photosynthetic algae exposed to radioactive CO₂ to see how plants made sugar
30
the most abundant protein on earth
RuBisCO
31
Every carbon in your body has been
processed by Rubisco
32
Rice and bamboo have a more efficient
more efficient C3 system that can reuse CO₂ released during photorespiration.
Stromules (tiny extensions of the chloroplasts) help with capturing CO₂.
These stromules are attached to the plant's internal support system (actin cytoskeleton)
33
3% of flowering plants
(sugarcane, corn, sorghum, many tropical grasses and some dicots) evolved an additional carbon-
fixation pathway known as the C4 pathway
34
C4 plants have evolved independently over
60 times in at least 19 different families of angiosperms
35
One of the most common forms of
convergent evolution?
C4 photosynthesis is a common example of convergent evolution
All C4 plants create oxaloacetate (OAA) in the first step, but the later steps in the pathway can differ significantly between species.
-First appeared in the Oligocene (24-35 millions years ago) in grasses, Most C4 dicot arose sometime in the last 5
million years
36
What is Crassulacean Acid Metabolism (CAM) and its key features
CAM was first discovered in the Crassulaceae family.
Evolved independently in succulents like pineapples, cacti, and stonecrops.
The defining feature is the ability to fix CO₂ at night using the enzyme PEP carboxylase (PEPC).
37
How do C4 plants perform photosynthesis?
C4 pathway and Calvin cycle run simultaneously.
They are spatially separated:
C4 pathway in mesophyll cells.
Calvin cycle in bundle sheath cells
38
How do CAM plants perform photosynthesis?
At night, CAM plants open their stomata to take in CO₂, which is fixed into malic acid and stored in vacuoles.
During the day, malic acid releases CO₂ for the Calvin cycle.
CAM plants keep stomata closed during the day, using stored CO₂.
39
How do plants improve photosynthesis?
Light harvesting:
Plants use two photosystems and pigments to absorb more light efficiently.
Energy generation:
Plants can use cyclic electron flow to produce extra energy when needed.
CO₂ fixation:
C4 plants: Separate CO₂ fixation and sugar production into different parts of the leaf.
Specialized C3 plants: Reuse CO₂ released during photorespiration.
CAM plants: Fix CO₂ at night and store it as malic acid for use during the day.
40
What happens in CAM plants during the day?
-Malic acid is released from the vacuole and decarboxylated to produce CO₂ and pyruvate.
-The CO₂ enters the Calvin cycle, where it's refixed by Rubisco.
-Stomatal closure prevents water loss and traps CO₂ released during decarboxylation
41
What happens in CAM plants at night?
-CO₂ is fixed when the stomata are open.
-Starch in the chloroplast is broken down to PEP (phosphoenolpyruvate).
-PEP carboxylase (PEPC) fixes HCO₃⁻ with PEP, forming oxaloacetate, which is reduced to malate.
-Malate is stored as malic acid in the vacuole.
42
Challenges Faced by Land Plants
-Harvesting light energy
■ Giving up the sea of moderation:
Getting out of the water
■ Staying wet when things get dry
■ Dealing with gravity
■ Competition
■ Leveraging resources
43
Key evolutionary innovations leading to plant land domination:
Better conducting tissue: Vessel elements transport water more effectively.
Efficient leaf plumbing: Improved venation for better water and nutrient flow.
Deciduous leaves: Leaves that fall off seasonally to conserve energy.
Diverse and specialized leaves: Leaves adapted for different environments and functions (most important innovation).
44
Biennial plants
Their life cycle takes two years.
In the first year, they grow leaves and roots.
In the second year, they flower, produce seeds, and then die.
Some parts of the plant, like roots, can live longer (e.g., parsley).
44
Annual plants
Life cycle completed in single
season (from seed germination to mature plant producing
seeds)
45
What are the two main classes of Angiosperms (Phylum Magnoliophyta)
Two main classes:
Magnoliopsida (formerly "Dicotyledonae" or Dicots)
Liliopsida (formerly "Monocotyledonae" or Monocots)
46
what defines primitive flowers?
Long receptacle: Supports the flower organs.
Spirally arranged flower parts: Not fused and arranged in a spiral.
Non-differentiated parts: Flower parts are not separated into distinct sepals, petals, etc.
Flattened, numerous stamens and carpels: Many stamens and carpels, not specialized.
47
Flower:
A modified stem bearing modified leaves.
48
What does "heterosporous" mean in Angiosperms?
Heterosporous means producing two different types of spores:
Microspores: small male spores
Macrospores: larger female spores
49
What is the difference between a spore and a gamete in Angiosperms?
A spore can develop into a new organism.
A gamete must fuse with another gamete to form a zygote.
50
What is the dominant generation in Angiosperms?
The sporophyte is the dominant generation in Angiosperms.
51
Describe the female gametophytes in Angiosperms.
Female gametophytes are:
completely enclosed within sporophyte tissue.
Reduced to only a few cells.
52
What does a mature male gametophyte consist of in Angiosperms?
A mature male gametophyte is a two-celled pollen grain.
53
Evolution of flowering plants
The evolution of flowers and fruits was the key feature that led
to their success
■ Seeds (developed from ovules) enclosed in an ovary (fruit at
maturity)
■ Flowers co-evolved with insect and animal pollinators
(specialized pollination)
■ Flowers are highly modified leaves
■ Cross-pollination enhanced
■ Widely separated plant populations can exchange and recombine
their genes
54
What are sporophylls in seedless vascular plants
Sporophylls are modified leaves that produce spores.
55
Where do sporangia(where spores are produced and stored) develop in gymnosperms?
In gymnosperms, sporangia develop within:
Sporophylls
Modified branches called strobili
56
Specialized flowers
Specialized flowers are flowers that have certain features to make them more efficient or unique:
The flower parts are fewer and have a specific number.
The flower parts are arranged in whorls (circles), not spirals.
The flower is bilaterally symmetrical (can only be divided into two equal parts, making it irregular).
Some parts of the flower might be reduced or fused together, meaning the flower isn’t complete or has imperfect parts.
The ovary (part of the flower where seeds form) is positioned lower, called an inferior ovary
57
Superior ovary
an ovary that is attached to the flower stalk (receptacle) above where the other flower parts are attached.
58
Clustering of stigmatic surface at the tip
Clustering of stigmatic surface at the tip to increase pollen landing
59
Complete flower
Has calyx, corolla,
stamens and pistil
60
Incomplete flower
Corolla or other
flower parts missing.
61
Perfect flower
Both stamens and
pistil present
62
Imperfect flower
Either stamens or pistil missing
63
Dioecious species
Plant bears only
male flowers and other plants bear only female flowers.
64
Monoecious species
monoecious species are plants that have separate male and female flowers on the same plant. imperfect flower
65
Inflorescence
Group of flowers
66
florets
Individual flowers
67
The Sunflower Family
(Asteraceae)
Second largest flowering
plant family
68
monocots
the grass family (poaceae)
69
Inbreeding depression
reduction in fitness
caused by an increase in homozygocity(similar genes)
70
inbreeding
occurs when individuals mate with close genetic relatives
with a greater likelihood than random, Self-fertilization is the strongest kind of inbreeding(happens a lot in plants with both male and female part)
71
Outbreeding
Outbreeding happens when individuals are less likely to mate with close relatives compared to random chance
72
Outcrossing plants had greater instances of
recessive lethal(harmful) alleles
72
Self-fertilizing plants have gotten rid of most
of these harmful alleles over time and have fewer of them.
73
Bee-pollinated flowers
Showy, brightly colored, mostly blue or yellow
– Sweet and fragrant
– Often have lines or distinctive markings, which function as nectar
guides.
* Bees see UV light (humans do not).
- Some flower markings visible only in UV light
74
Beetle-pollinated flowers
* Strong, yeasty, spicy or fruity odor
* White or dull in color (beetles do not have keen visual senses).
* Some do not produce nectar, but provide pollen or food on
petals in special storage cells.
75
Fly-pollinated flowers:
*Smell like rotten meat
* Dull red or brown
76
Who were the earliest pollinators?
What is the role of beetles in pollination?
The earliest pollinators were likely beetles, with evidence found in amber showing beetles with pollen from 99 million years ago.
Beetles carry pollen but are more destructive than other pollinators, eating flowers and petals.
Flowers attract beetles, then fade to encourage them to leave.
Magnolias sacrifice some leaf and pollen tissues to protect their female reproductive parts from beetle damage.
77
Butterfly- and moth-pollinated flowers
*Often have sweet fragrances
* White or yellow for night-flying moths
* Often blue, yellow or orange for butterflies (sometimes red)
* Nectaries at bases of corolla tubes or spurs for long
tongues
78
Bird-pollinated flowers (hummingbirds and sunbirds)
*Often bright red or yellow
* Little if any odor (birds do not have a keen sense of smell).
* Large and sturdy inflorescence
* Large amounts of nectar (birds are highly active).
* Nectar found in long floral tubes
78
Bat-pollinated flowers
*Primarily in tropics
* Open at night when bats are foraging
* Dull in color
* Large enough for bat to insert head or consist of ball-like inflorescence containing large numbers of small flowers
79
80
Orchid flowers
* Have pollinators among all types
* Some of adaptations between orchid flowers and pollinators are extraordinary.
* Pollen grains found in sacs called pollinia (singular: pollinium) with sticky pads at base.
* Members of Ophrys have modified petal that resembles
female bumble bee or wasp
- Male bees or wasps try to
mate with flower (Pollinia
deposited on their head)
81
Fruit:
A fruit is a mature ovary (and sometimes additional parts) of a flower. It contains seeds and develops only in flowering plants.
Fruits can be fresh (like peaches) or dry at maturity.
82
Fleshy Fruits
Mesocarp is fleshy at maturity.
simple fleshy fruits develop from flower with single pistil.
83
Fleshy Fruit (3 main types) (fleshy means soft)
1.Drupe – Single seed inside a stony endocarp (pit). Examples: peaches, almonds, olives.
2.Berries – From compound ovary, multiple seeds, and fleshy pericarp.
True berries – Thin skin, soft pericarp. Examples: tomatoes, grapes, peppers, blueberries, bananas, eggplant.
Pepo – Thick rind. Examples: pumpkins, cucumbers.
Hesperidium – Leathery skin with oils. Example: citrus fruits.
Not Berries!!: strawberries, raspberries, blackberries.
3. Pome – Flesh from enlarged floral tube or hypanthium. Examples: apples, pears.
84
Dry Fruits
Mesocarp dry at maturity
types : Dehiscent: Split open at maturity.
Indehiscent: Do not split open at maturity
85
Dehiscent Fruits
Capsules - Consist of at least two carpels, and split in a variety of ways
– Irises, poppies, violets, snapdragon
86
indehiscent Fruits
Do Not Split at Maturity
* Single seed united with pericarp(outerlayer)
Achene (e.g., sunflower)
Nuts (e.g., acorn)
Grain/caryopsis (e.g., corn, rice)
Samaras (e.g., maples)
Schizocarp (e.g., carrots)
87
Dry Fruits, Aggregate Fruits
from single flower with several to many pistils that mature on
a swollen receptacle(the part where all the pistils are attached). (each pistle turns into fruit)(raspberries, blackberries, strawberries
88
Dry Fruits, Multiple Fruits
come from several to many individual flowers in single inflorescence(Each flower in the group contributes to making the fruit) (Mulberries, Osage orange, pineapples, figs)
89
Dispersal by Wind
Fruits: Samaras(wings), plumes(fluffy parts) or hairs on fruit
* Seeds: Small and lightweight, or with wings
90
Water Dispersal
*Some fruits contain inflated covering for floatation.
* Water dispersal is called hydrocolloid or hydrochory
* Water lilies and palm trees
91
Dispersal by Animals
Seeds pass through digestive tract.
* some seeds have Oily parts (Elaiosomes) that attract ants.
* Fruits and seeds adhere to fur or feathers
92
Favorable environmental factors needed for germination.
* Water
* Oxygen
* Proper temperature range
* Light (red spectrum)
93
Vivipary
No period of dormancy; embryo
continues to grow while fruit is still on parent.
❖ Occurs in places with less seasonal variation
❖ No need to delay for better conditions
94
Asexual reproduction
occurs through mitosis (vegetative fragmentation, spore formation): offspring are genetically identical. will quickly propagate
itself (selective advantage)= will spread quickly
95
Sexual reproduction
-results in genetic variation (fusion of gametes).
-Gametes (sperm and egg) fuse to produce a zygote
-Enhance adaptability to changing environments and facilitates colonization of new environments
96
Plant Sexual Cycles
Plants have two multicellular forms [gametophyte (1n) and sporophyte (2n)]
■ Bryophytes: gametophyte dominant
■ Seedless Vascular Plants: Sporophyte is dominant (two are independent)
■ Seed Plants: Sporophyte is dominant and gametophyte is significantly reduced
97
Somatic Cells-non-reproductive cells that make up your skin, muscles, bones, organs, and tissues.
* mitotically dividing(identical copies) and G-arrested cells( cells in a resting state, not dividing but still active)
* make up vast majority of individual’s tissues
* diploid (2n)
mutations don't matter
98
Germ Cells
* pockets of specialized cells (2n for diploid)
* undergo meiosis to produce gametes (egg/sperm, 1n)
mutations matter
99
Variation in the types of spores produced- Bryophytes
single type of spore gives rise to separate male and female gametophytes
100
Variation in the types of spores produced-Ferns
single type of spore gives rise to a bisexual gametophyte
101
Variation in the types of spores produced-Seed plants
two types of spores are made (megaspore producing the female gametophyte and the microspore that produces the male gametophyte)
102
Apomixis
seeds are produced asexually
without pollination (no fusion of gametes )
* Embryo formed from diploid nutritive cell or other diploid
cell of ovule, instead of from zygote.
– dandelions
102
* Pollination
Transfer of pollen grains from anther to stigma
103
Double fertilization
One sperm unites with egg, forming zygote, then embryo.
* Other sperm unites with central cell nuclei that develops
into endosperm tissue [triploid (3n)].
103
Self-pollination
Pollen grains germinate on stigma of same flower
104
Parthenocarpy
Fruits develop from ovaries
with unfertilized eggs.
* Results in seedless fruits
– Navel oranges, bananas, watermelons, cucumbers
105
Tropism
a growth response involving bending, or curving, of a
plant toward or away from an external stimulus that determines
the direction of movement
106
Tropic growth occurs in response to
-light (phototropism)
* gravity (geotropism)
* touch (thigmotropism)
* chemicals (chemotropism)
* water (hydrotropism)
107
photomorphogenic
responses
Light triggered growth and
developmental responses
108
Etiolated
refers to a condition in plants where seedlings or shoots grow in the absence of light. The stems grow longer than normal (to search for light).
The leaves are small and underdeveloped.
The plant looks pale or yellow because it lacks chlorophyll, which cannot develop without light.
109
Light regulates many aspects of plant growth
1. Polar cell growth (differential expansion)
2. Chloroplast movements
3. Elongation growth of tissues
4. Germination
5. Flowering time
6. Seasonal responses
110
Auxins are transported out of the cell
using active transport via two groups of membrane bound proteins (PIN and ABCB)
111
2,4-D is
is a synthetic auxin, which means it is a man-made version of a natural plant hormone that helps control plant growth
112
Enlist Duo
was sold in 2014, which combined two herbicides: 2,4-D and Roundup (glyphosate). It was used with specially designed crops like Enlist Soy and Enlist Corn.
112
bacterial enzyme
in plants enhance there resistant to 2,4-d
113
Waterhemp (Amaranthus tuberculatus) or pigweed
One of the most pervasive weeds in places like Iowa, it wasn’t a serious weed until the mid-1980s. Glyphosate resistant weeds. Replacing redroot pigweed and smooth pigweed.1980s was a period of rapid herbicide development
114
Canadian Horseweed
compete with crops for resources and release chemicals (allelopathy) that inhibit other plants
This weed can reduce soybean production by up to 90% and also harms crops like corn, wheat, radish, and tomatoes.
Key Point: Weeds adapt to survive, making weed control harder.
115
Negative allelopathy:
Stops other plants from growing or germinating
116
Positive allelopathy
Helps other plants grow.
117
“Rondo” rice
Rondo rice is a transgenic indica rice (Oryza sativa). Indica rice makes up 80% of global rice cultivation. Rondo rice has greater harvest height, shoot biomass, and crop yields compared to non-transgenic rice, especially in fields with additional weed suppression.
118
What effect does blue light have on plasma membrane proteins?
Blue light induces phosphorylation of two plasma membrane proteins.
Phosphorylation is when a phosphate group is added to a protein, which can change its function or activity.
119
Were scientists successful in purifying phosphorylated proteins that retained photosensitivity in the 1980s?
No, attempts to purify photosensitive phosphorylated proteins were unsuccessful.
120
Studies with Arabidopsis plants that couldn’t grow toward light properly (mutants) helped
helped scientists find blue light receptors. These receptors are called phototropin and cryptochrome (CRY). Phototropin and cryptochrome absorb blue light, while another receptor, phytochrome, absorbs red light.
120
Phototropins I and II are special proteins that help plants sense blue light. They have two key parts:
LOV domains: These parts of the protein can bind to a molecule called flavin mononucleotide (FMN), which helps them absorb blue light.
Kinase domains: These parts can add a "phosphate" (a tiny chemical group) to specific parts of other proteins, which changes the protein's activity. They also "autophosphorylate," which means they add a phosphate to themselves
121
Phototropins I and II
Function: Blue light receptors that activate themselves (autophosphorylate) and signal auxin to move to the dark side of the stem, causing phototropic growth.
Family: Part of the PAS protein family, which detects light, oxygen, and voltage (LOV domain).
Example: Related to circadian clock proteins like period in Drosophila.
122
hypocotyl
the region under cotelydon in a
germinating seed that will form the
stem
122
Order Protein structure of Phototropins I and II
LOV domains: These are flavin mononucleotide (FMN) binding domains that help phototropins absorb blue light.
Kinase domains: These regions phosphorylate serine/threonine amino acids in a target protein (substrate).
Autophosphorylation: Phototropins phosphorylate themselves as part of their activation process.
122
What are the roles of Phot1 and Phot2 in plants?
Phot1 and Phot2 regulate hypocotyl phototropism (growth towards light). Both respond to high-intensity blue light, but Phot1 also works in low-light conditions.
122
How were Phot1 and Phot2 functions tested?
Their functions were tested using knockout mutations, which disable specific genes to observe their roles
122
Accumulation response:
low light
response where chloroplasts
distribute uniformly to maximize light
capture
123
Avoidance response
a high light response where chloroplasts
redistribute to minimize
photodamage
124
Homologs
are genes that are derived
from common ancestry.
125
Paralog
A pair of homologs derived
from a gene duplication event
126
Ortholog:
a pair of homologs derived
from a speciation event.
127
photoperiod
Plants can sense the relative length of night and day
128
short-day plants, SDP
Some plants flower when day length becomes short
ex Soybean (Glycine max)
* Cotton (Gossypium)
* Rice (Oryza)
* Marijuana (Cannabis)
* Sorghum (Sorghum bicolor) (fake light hits too early wont grow)
129
long-day plants, LDP
Some plants flower when day length become long
ex Wheat (Triticum aestivum)
* Lettuce (Lactuca sativa)
* Oat (Avena)
* Barrey (Hordeum vulgare) ****(night too long wont grow)
130
day-neutral
Plants that are unaffected by day length
131
What are some impacts of urbanization on biodiversity and species?
55% of the human population lives in cities, covering 3% of Earth's land surface.
Effects of urbanization:
Habitat fragmentation
Lower species diversity
Increased species invasion
Loss of native species
Convergent evolution making urban populations more similar across distant urban sites
132
What were some early views and impacts on urban ecology?
Early ecologists believed cities were "anti-life" and didn’t focus on urban ecology.
Pollution increases mutation rates, potentially speeding up evolution in urban environments.
Fragmented ecosystems lead to smaller populations, which can cause genetic drift.
133
Precision Agriculture
breeders use special tools (sensors) and computer models to carefully control and adjust things like temperature, light, and water to help plants or animals grow better.
134
Genetic drift
reduces within
population diversity and increases
between population divergence
135
Entrainment
is the synchronization of the biological clock to the environmental cycle. Keep running under constant environmental conditions (continuous light) the rhythm is free-running and behaves
as a self- sustained oscillator (approx. 21-27 hours)
136
What was Norman Borlaug's contribution to the Green Revolution
Norman Borlaug won the Nobel Peace Prize in 1970 for his work in Mexico.
The Green Revolution introduced hybrid corn and wheat to boost yields in arid environments. Impact (1940-1960):
Corn production tripled.
Wheat production increased 5-fold.
137
What changes in agriculture occurred since 1961 to support a doubling global population?
Shift from subsistence farming to modern systems:
Traditional tools: Wooden plows, waterwheels, bullock carts.
Technology transfer:
High-yield wheat and rice variants.
Fertilizers and pesticides.
Mechanical threshers.
Genetic engineering.
138
What led to the Green Revolution in India?
In 1947, 90% of people lived in villages relying on subsistence farming.
No change in wheat/rice farming for centuries.
18th-century tech improvements focused on cash crops (coffee, cotton, rubber, spices, tea).
The Green Revolution relied on High-Yielding Varieties (HYV) of seeds.
