Lecture Final Summary

Botany Lecture

Microphylls:

Found in ______

lycophytes

Microphylls:

Originated as:

Simple, single-vein outgrowths of the stem

Microphylls:

Small and generally lack _______ venation

complex

Megaphylls:

Larger leaves with ________ venation

complex

Megaphylls:

Evolved from branch systems through ______ and ______

webbing

fusion

Megaphylls:

Present in ____, ________, and ________

ferns

gymnosperms

angiosperms

Fern Life Cycle:

Sporophyte (2n):

Dominant, photosynthetic stage producing spores in sporangia

Fern Life Cycle:

Gametophyte (n):

Small, heart-shaped structure that supports fertilization; produces antheridia and archegonia

Fern Life Cycle:

Spore dispersal relies on environmental triggers like ______ and _______

wind

humidity

Horsetails:

Stems contain ______, aiding rigidity

silica

Horsetails:

________ and ________ are specialized structures for gamete production

Archegoniophore

Antheridiophore

Psilotum:

Simplified structure with ______ stems

photosynthetic

Psilotum:

No true roots; uses _____ for anchorage and absorption

rhizoids

Pine Life Cycle:

Male cones produced ______, developing into ____ _____

microspores

pollen grains

Pine Life Cycle:

Female cones produce ______, developing into _______

megaspores

ovules

Pine Life Cycle:

Pollination is ____-_____, and fertilization occurs after a significant time lag

wind-driven

Pine Life Cycle:

Seed formation follows, enclosing the embryo within a _______ ________

protective coat

Ginko biloba:

Dioecious

Distinct fan-shaped leaves and fleshy seed coverings

Cycads:

Ancient lineage with large, compound leaves

Symbiosis with nitrogen-fixing cyanobacteria

Reproductive structures include cones

Polyembryony:

Occurs when multiple embryos form within one ovule.

Common in gymnosperms like pine, though only one typically survives

Main Plant Hormones:

Auxins

Cytokinins

Gibberellins

Abscisic acid

Ethylene

Auxins are synthesized in _____ _______

shoot apices

Auxins promote _____, ______, and ______

elongation

phototropism

gravitropism

Cytokinins are produced in _____ and transported to ______

roots

shoots

Cytokinins promote _____ ______ and delay _____ _______

cell division

Leaf senescence

Gibberellins Stimulate ______ _____, ______ ______, and ________

stem elongation

seed germination

flowering

Gibberellins are key in overcoming __________

dormancy

Abscisic Acid induces ______ _____ during drought

stomatal

closure

Abscisic Acid maintains ______ __________

seed

dormancy

Ethylene:

Gas that regulates ______ ______ and responses to _______ _______

fruit ripening

environmental stress

Auxins and cytokinins regulate ____ and _____ formation in tissue culture

shoot

root

Ethylene and ABA mediate responses to ______ _______

environmental stress

Phototropism:

Growth towards or away from light, mediated by auxins

Gravitropism:

Root growth downward and shoot grown upward

Positive Gravitropism:

Root growth downward

Negative Gravitropism:

Shoot growth upward

Thigmotropism:

Response to touch; climbing plants wrap around supports

Hydrotropism:

Root grow towards water sources

Nastic Movements:

Non-directional movements

Non-direction movements:

driven by changes in turgor pressure or growth differentials

Nyctinasty:

Sleep movements in response to circadian rhythms

Photoperiodism:

Mechanism by which plants detect day/night lengths to time flowering

Short-day plants:

Flower when nights are long

Long-day plants:

Flower when nights are short

Day-neutral plants:

Unaffected by photoperiod

Phytochrome System:

Light-sensitive pigment in two interconvertible forms

Pr absorbs ____ ____ and converts it to Pfr

red light

Pfr absorbs ____ _____ ____ and converts back to Pr

far-red

light

Pfr acts as a signal for _____-_____ ____ and ________

light-dependent growth

development

What are two examples of plant responses to environmental stimuli?

stress responses

water conservation

Stress Responses:

Drought salinity, and temperature extremes trigger ____-_____ stomal closure, protein stabilization, and osmotic adjustment

ABA-mediated

Stress Response:

_______ adaptations like shedding leaves under prolonged drought

Ephemeral

Water Conservation:

_________ cells fold leaves to reduce surface area exposed to sunlight, minimizing water loss

Bulliform

Circadian Rhythms:

Govern daily physiological and behavioral activities

Circadian Rhythms:

_____ _____ for gas exchange during the day

stomatal opening

Circadian Rhythms:

_______ ______ like leaf folding at night

Nyctinastic movements

Circadian Rhythms:

__________ in certain species for predation or symbiosis

Bioluminescence

What is the difference between megaphylls and microphylls?

Megaphylls have branching veins and evolved from webbing between branches, common in ferns and seed plants. Microphylls have a single vein and no leaf gaps, found in lycophytes.

Describe the fern life cycle:

The fern life cycle includes alternation of generations, where a dominant sporophyte produces spores through meiosis, which develop into a gametophyte. The gametophyte then produces gametes that fuse to form a new sporophyte.

What are the morphological characteristics of horsetails?

Jointed, photosynthetic stems containing silica

Whorled microphyll-like leaves

Structure like archegoniophores and antheridiophores for reproduction

What is polyembryony in gymnosperms?

Polyembryony in gymnosperms is the phenomenon where multiple embryos develop from a single fertilized ovule, leading to the formation of several seeds from one ovule.

What is the role of phytochrome in photoperiodism?

Phytochrome is a plant photoreceptor that detects light and regulates gene expression in response to light conditions, playing a crucial role in controlling flowering and growth based on day length.

What are tropisms?

Tropisms are growth responses of plants to environmental stimuli, such as light (phototropism), gravity (gravitropism), and touch (thigmotropism), influencing their direction of growth.

What is the difference between nastic movements and tropisms?

Nastic movements are non-directional responses to stimuli, whereas tropisms are directional growth responses influenced by environmental factors.

How do male and female pine cones differ?

Male cones (microstrobili) are smaller and produce pollen. Female cones(megastrobili) are larger and contain ovules that develop into seeds after fertilization.

What are the main features of Ginkgo biloba?

A deciduous gymnosperm with fan-shaped leaves, dichotomous venation, and separate male and female trees. It produces seeds with fleshy coatings.