Botany

Flashcards for Professor Dave's principles of Botany series.

Chloroplast

A specialized organelle found in plant cells and some algae, responsible for photosynthesis by converting light energy into chemical energy in the form of glucose.

Central Vacuole

A large organelle found in plant cells, primarily responsible for storing water, nutrients, and waste products, and maintaining turgor pressure.

Cell Wall

A rigid outer layer surrounding the cell membrane in plant cells, fungi, and some bacteria, providing structural support and protection against mechanical stress.

2 Steps of photosynthesis.

The two main steps of photosynthesis are the light-dependent reactions, which capture and convert solar energy into chemical energy, and the Calvin cycle (light-independent reactions), which uses that energy to synthesize glucose from carbon dioxide.

Thylakoid

A membrane-bound structure within chloroplasts where the light-dependent reactions of photosynthesis occur, containing chlorophyll and other pigments.

Stroma

The fluid-filled space surrounding thylakoids in chloroplasts, where the Calvin cycle takes place.

Porphyrin ring of Chlorophyll

Cyclic tetrapyrrole structure with a central magnesium ion that absorbs sunlight for photosynthesis.

Photosystem

A multi-protein complex found in the thylakoid membranes of plants, algae, and cyanobacteria that absorbs light energy and uses it to transfer electrons during photosynthesis

Summary of Light Reactions

Use sunlight and water to produce ATP, NADPH, and oxygen gas. They happen in the thylakoid membranes inside plant chloroplasts.

Summary of Calvin Cycle

The Calvin Cycle is a set of light-independent reactions in photosynthesis where plants use energy from ATP and NADPH to turn carbon dioxide into sugar.

Middle Lamella

The middle lamella is an outer layer of plant cell walls that acts as a natural glue to hold adjacent cells together.

Plasmodesmata

Tiny channels that cross the cell walls of plants and some algae, linking the living parts of neighboring cells together.

Meristematic Cells

Undifferentiated plant cells that continuously divide by mitosis to drive plant growth and development.

Parenchyma Cells

Living, thin-walled plant cells that form the bulk of soft plant tissues, such as leaf interiors, fruit pulp, and stem pith.

Collenchyma Cells

Living plant cells that provide flexible structural support and tensile strength to growing plant organs like young stems and leaves.

Sclerenchyma Cells

Rigid, dead plant cells with thick, lignified secondary walls that provide primary structural support and mechanical strength to mature plant parts. Woody tissue.

Parenchyma Ground Tissue

The most common and abundant type of ground tissue in plants, forming the bulk of leaves, roots, stems, and fruit pulp. Makes up the Mesophyll and stores stores starch in seeds. Responsible for covering wounds and replacing lost tissue.

Ground Collenchyma/Sclerenchyma Tissue

Collenchyma and sclerenchyma are two types of supportive ground tissue in plants that provide structural strength.

Dermal Tissue

Dermal tissue is the outer protective layer of a plant that acts much like skin to shield it from damage, disease, and water loss.

Stomata/Guard Cells

Guard cells are specialized, bean- or dumbbell-shaped pairs of cells on plant leaves that control the opening and closing of microscopic pores called stomata.

Cuticle

A protective, waxy outer layer covering the aerial (above-ground) parts of land plants, such as leaves, young stems, and flowers.

Periderm/Rhytidome

The periderm is a protective secondary tissue that replaces the epidermis in woody stems and roots, while the rhytidome is the outer, dead part of the bark made of multiple layers of old periderms and trapped non-functional phloem.

Vascular Tissue

Acts as a plant's circulatory system, consisting of specialized tubes that transport water, minerals, and food throughout roots, stems, and leaves. Not present in all plants, allows plants to be much bigger and away from water.

Xylem

Dead vascular tissue in plants that transports water and dissolved minerals upward from the roots to the stems and leaves. Made of lignin. Contains tracheids and vessel elements.

Phloem

the living vascular tissue in plants that moves sugars and other organic compounds made during photosynthesis from the leaves to the rest of the plant. Contained Companion Cells and Sieve Cells.

Transpiration vs Translocation

Transpiration is the loss of water vapor from a plant's leaves through evaporation, while translocation is the movement of dissolved sugars and nutrients throughout the plant.

Soil Plant Atmosphere Continuum

The pathway of water moving continuously from the soil, through a plant, and into the atmosphere.

Shoot System

Shoot system is the above-ground part of a vascular plant that includes the stems, leaves, buds, flowers, and fruits.

Root System

The underground network that anchors the plant and absorbs water and essential minerals from the soil. It contains the roots, tubers, and rhizomes.

Rhizomes

A modified horizontal stem that usually grows just below or along the soil surface, producing roots and new shoots from its nodes.

Parts of a flower.

Hermaphroditic.

Contains both male and female sex cells.

Functions of roots.

Absorb water and minerals from the soil and anchor the plant firmly in the ground. Also form places for some bacteria and fungi to live. Many plants store starch in the roots.

Apical Meristem

An apical meristem is a region of actively dividing, undifferentiated cells located at the tips of roots and shoots that drives primary, vertical growth in plants.

Lateral Meristem

plant tissues responsible for secondary growth, which increases the width, diameter, or girth of a plant's stems, branches, and roots. Located in the Cambium of the stem.

Auxin

Plant hormones produced mainly in shoot tips and young leaves that stimulate cell elongation and direct plant growth.

Cytokinin

primarily promote cell division (cytokinesis) in roots and shoots.

Gibberellins

Regulate growth, stem elongation, and seed germination.

Abscisic Acid

Abscisic acid (ABA) is a major plant hormone that acts primarily as a growth inhibitor and a key stress signal helping plants survive harsh environmental conditions.

Ethylene

Volatile hydrocarbon gas that acts as a vital plant hormone regulating growth, development, aging, and stress responses.

Carotenoids

Carotenoids are natural yellow, orange, and red pigments produced by plants, algae, and some bacteria and fungi that are essential for photosynthesis and photoprotection.

Flavonoids

a large group of natural plant compounds that give many fruits, vegetables, and flowers their vibrant colors and provide health benefits for humans.

Phytochrome

Phytochrome is a photoreceptor protein found in plants, bacteria, and fungi that detects red and far-red light to regulate growth and development.

The 6 major plant developments chronologically.

Algae → Bryophytes → Lycophytes → Ferns → Gymnosperms → Angiosperms

Algae

Algae are a diverse group of mostly aquatic, nucleus-bearing (eukaryotic) organisms that make their own food through photosynthesis but lack true roots, stems, leaves, and complex reproductive structures found in true plants.

Types of Bryophytes

Mosses, liverworts, and hornworts.

Bryophyte qualities.

Bryophytes require a source of water, but do not need to be submerged in it. Contain rhizoids, root like appendages. They have no true leaves or stem, their body is called a thallus. They undergo sexual reproduction in a heteromorphic development cycle.

Bryophyte development cycle

Gametophyte

Gametophyte is the haploid, multicellular stage in the life cycle of plants and algae that produces sexual gametes through mitosis.

Sporophyte

The diploid, spore-producing phase in the life cycle of plants and certain algae that undergo alternation of generations

Lycophytes (Club mosses) qualities

Oldest living vascular plants. Use dichotomous branching. Bear ancient leaf descendant called Microphylls. Lycophyte spores are used for their high fat content.

Lycophyte life cycle.

Fern qualities

First vascular plants with true stems. Bear leaf like appendages called megaphylls. They are small/medium sized plants which are herbaceous (no woody tissue above ground). Scouring Rushes and Horsetails are highly related. Can be both epiphytic and epipetric. Some ferns can use vegetative reproduction making them frustrating weeds.

Fern life cycle

Epiphytic

Grow on other plants.

Epipetric

Grow on rocks.

Vegetative Reproduction.

Vegetative reproduction is a type of asexual plant reproduction where a new plant grows from a part or fragment of a parent plant instead of from a seed or spore.

Spermatophytes

Seed bearing plants

Gymnosperm qualities.

Spermatophytes who seeds are not in chambers like fruits/nuts. Contains Conifers, Cycads, and Ginkgo. Pollination done by wind. Water not required for fertilization letting them grow in dry land. Conifers create pollen tubes to facilitate sperm and egg to meet.

Gymnosperm life cycle

Angiosperm qualities

Spermatophyte who places seed into chambers like nuts and fruits. Take advantage of animals for spreading seeds and pollination. Ovary swells into fruits, whose function is to spread seeds. Uses a process called double fertilization during life cycle. Commonly referred to as the most successful form of plants for their abundance.

Plant Tropisms

Movement/Growth towards/away from a specific stimulus.

Phototropism

Growth in response to light.

Heliotropism

Growth in response to sun location.

Gravi/Geo tropism

Growth in response to gravity.

Hydrotropism

Growth in response to water concentration.

Thigmotropism

Growth in response to physical touch.

Chemotropism

Growth in response to chemical concentration.

Thermotropism

Growth in response to heat.

Plant circadian rhythm

Internal self-sustaining 24-hour biological clock that lets the plant anticipate daily changes in light, temperature, and humidity rather than just reacting to them

Phenology

The study of the timing of biological life-cycle events in plants, such as leaf budding, flowering, and fruit ripening, as driven by weather and climate.

Plant physical defenses

Thorns/Spines

Tough outer coating

Tiny hairs

High silica concentration

Plant chemical defenses

Poison

Bad smell

Bad taste

Mimic insect growth hormones

Cladogram of the 8 main Angiosperms

C3 Photosynthesis

Common photosynthesis used in plants evolved to live in non dry environments.

C4 Photosynthesis

Photosynthesis used in plants who need to close their stomata periodically.

Creates 4CC and breaks it up into CO2 to use in the Calvin Cycle.

CAM Photosynthesis

Photosynthesis used in plants who need to close stomata in the day.

Stores CO4 during night and breaks it up during the day, without needing to open Stomata.

Dendrochronology

Study of trees to learn historic information about temperatures, rainfall, insect outbreak, fires, etc.

Keep track of global climate shifts in the last 300-1000 years.