BIO 152 - Plants

Flashcards for various terms/processes discussed in the Plants module of Bio 152 (2025) at UW-Madison, as taught by Dr. Simon Gilroy.

Indeterminate growth

growth with no genetically predefined limits

Determinate growth

growth with genetically predefined limits

Eukaryotic

organisms whose cells have membrane-bound nuclei

Stem cells

cells that divide to generate specialized cells

plants use these cells to prolong their life span and heal themselves

Cyanobacteria

aquatic and photosynthetic organisms that are technically bacteria → led the way for more complex photosynthetic eukaryotes to appear

Photosynthesis

a light-powered process used by plants, algae, and bacteria to generate oxygen as a byproduct, allows plants to obtain energy

Evolution

the process by which heritable traits of a biological population change over time, resulting from mutations that produce genomic variation

Alga

eukaryotic organisms lacking vascular systems and not true plants, but still photosynthetic, and are the ancestors of modern day land plants

Holdfast

an organ used in alga species to grip substrate and stick themselves to one spot (how they have come to evolve without roots)

Rhizoid

anchors for moss that absorb nutrients and water, appear similar to roots but are not true roots,

Charophyte

the closest modern-day algae relative of embryophytes (true plants) - NOT an ancestor, a sister clade

Embryophyte

the first true land plants

Roots

used to anchor plants into the ground, contain vascular tissue and function to absorb water and nutrients

Diploid

a cell containing two complete sets of chromosomes, one from each parent

Haploid

cells with one set of chromosomes (gametes)

Fertilization

process of sexual reproduction where male and female gametes produces a diploid zygote

Zygote

a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum

Gamete

a mature haploid male or female cell that fuses with another haploid cell during fertilization

Meiosis

a type of cell division with a two-part process that produces reproductive cells (gametes)

produces 4 genetically unique daughter strictly haploid cells (gametes)

Mitosis

a type of cell division that produces two identical diiploid/haploid daughter cells

Sporpollenin

a protective bipolymer that forms the outer shell of plant spores and pollen grains

Gametophyte generation

a haploid stage that makes gametes who will produce new sporophyte generations

Sporophyte generation

a diploid stage which makes spores that will grow into a gametophyte generation

Alternations of generations

a life cycle that involves alternating between a haploid phase and a diploid phase, which enables genetic diversity through sexual reproduction while also providing flexibility to adapt to different environmental conditions

Moss

a nonvascular bryophyte, that is compact, has rhizoids, can form large photosynthetic carpets, and have flagellated sperm so they depend on watery environments

Bryophytes

nonvascular, gametophyte dominant plants

posess a waxy cuticle an sometimes stomatal pores (allow diffusion of gasses)

Spore

a unicellular haploid reproductive unit that can develop into a new plant without needing to fuse with another cell

Cuticle

waxy film that protects the outer layer of leaves, stems, flowers, and fruits - waterproofing layer

Seedless Vascular Plants

ferns and relatives that reproduce using airborne spores produced in sporangia

Egg

female gamete

Sperm

male gamete

Gymnosperms

vascular, cone-bearing plants that produce pollen and seeds for reproduction

• seeds are exposed in cones

• spores never leave specialized tissues within the sporophyte (two types of spores)

Microspores

produce male gametophyte which will make sperm - the key to pollen (in male cones)

gametophyte gets encased in sporopollenin and becomes a pollen grain

Megaspores

produce female gametophyte which will make eggs

Angiosperms

flowering plants that reproduce using pollen and seeds, have both flowers and fruit

split into two categories based on cotyledons

Cotyledons

seed leaves, the first leaf-like structures that emerge when the seedling germinates - a food reserve for the embryo in the seed

Monocots

angiosperms that have one cotyledon during development

Dicots

angiosperms that have two cotyledons during development

Seed

an embryo of a plant encased in a seed coat

• in gymnosperms - seeds → female cones

• in angiosperms - seeds formed in flowers → fruit surrounding seed

Pollen

a packaged male gametophyte reduced to 2 cells that is delivered to the female reproductive structures

• in gymnosperms - created from microspores in male cones

• in angiosperms - created in the anther

Stomatal Pore

microscopic pores in the leaves and stems of plants that allow CO2 and O2 to diffuse

Sepal

the outermost layer of a flower that encloses the flower when it is still a bud and protects the internal structures

Carpel

the female reproductive structure of a flower

contains ovary at the base, which encloses developing seeds and eventually becomes the fruit around them

Stamen

the male sexual structure of a flower

consists of an anther atop a stalk called the filament

Petal

structures interior to the sepals - colorful to lure in pollinators

Ovary

at the base of the carpel and contains ovules

Ovule

sacs within which a microscopic female megaspore is produced by meiosis

Anther

the reproductively active part of the stamen → within its tissues are cells where meiosis will occur to produce microspores which will produce pollen

Stigma

the widened part at the top of the carpel which extends from the style

receptive and the pollen grains’ target destination

Lateral root

branches of roots that grow off primary roots and grow further via primary growth

Tap root system

more common in dicots - a root system with a large central root that grows straight down into the ground, with small lateral roots branching off

Fibrous root system

more prevalent in monocots - a root system with a network of thin, similarly sized roots that spread out near the soil surface

Root apices

the tip of a root which possess root hairs that extend out into the soil that increase surface area of the root absorb water and minerals

Stem

structures that support all other shoot structures

Leaf

responsible for photosnynthesis

Petiole

a leaf stalk that connects the leaf to the stalk

Reproductive shoots

shoots that bear flowers

Vegetative shoots

the rest of the shoots of a plant that grow and produce leaves but not flowers (sterile)

Root system

the part of the plant growing underground ( roots)

involved in absorption of water and minerals from the soil for distribution throughout the plant

Shoot system

the part of the plant growing above ground (leaves and stems)

involved in photosynthesis

Primary root

a plants first true root (the first part of a plant to emerge from a seed during germination), possessing an apical meristem

Apical bud

a bud at the tip of a plant’s stem or branch, which contains the meristem tissue where cell division occurs (primary growth)

Axillary bud

buds that are usually inactive unless cued by environmental conditions but located in the v-shaped spaces formed between the petiole and the stem

contain meristem tissue and can then develop into branches or shoots

Node

the points on the shoot where leaves connect to the stems

Internode

segments of the stem that are between the nodes

Leaf blade

the broad, flat surface of a leaf

Leaf vein

vascular tissue that connects the cells of the leaf to the rest of the plant, and supply rigid elements for support

allow nutrient transport through water

Leaf midrib

the main vascular bundle that extends out from the petiole and into the leaf blade

connects leaf’s vasculature to the rest of the shoot and supports the blade

Tissue system

three main systems: dermal tissue (plant exterior), ground tissue (space between dermal and vascular), and vascular tissue (water/nutrient transport) - work together to provide protection, support, and transport

Dermal tissue

protective, external layer of cells, act as a barrier between the interior and exterior of a plant

Ground tissue

all of the tissue between dermal and vascular, plays a critical role in structural support, storage, and conducting photosynthesi

occurs in the cortex, or pith, and consists of collenchyma, parenchyma, and sclerenchyma cells (structural support)

Collenchyma

cell in ground tissue that is specialized to physically support the plant

have thick cell walls that are flexible and can stretch as they grow by elongation

Sclerenchyma

cell in ground tissue that also functions as structural support

much thicker and more rigid cell walls and cells do not grow or stretch

dead at maturty, contains lignin

Parenchyma

the most abundant type of cell in ground tissue

function as multipurpose filler cells with thin and flexible cell walls

they can divide, but aren’t usually unless activated to do so

Vascular tissue

comprised of tube-like cells forming a system of vessels to conduct water and nutrient through the entire plant

made up of xylem and phloem

Xylem

conducts water and dissolved minerals from the soil UP through the plant

• dead and empty when they function for transport

• while alive, produce thick cell walls to resist the pressures of water

Vessel element

• cylinder-shaped cells with top and bottom cell walls - allows liquid to easily pass up through column

Tracheid

a type of xylem cell that is long, tube-like and closed off at both ends

water passes through via pores that connect them to other neighboring tracheids

Phloem

moves sugars around the plant from where they are made to where they are required

source → sink

• alive when functioning

Sieve plates

perforated cell walls at the top and bottom of each phloem cell to allow solution to move through

Sieve-tube elements

cells within the phloem where the cytoplasm is connected and continuous with the cytoplasm of cells above and below it through pores in sieve plates

• no organelles within cell itself but has..

• companion cell: functional cell with organelles that are coupled to it to supply with ATP and proteins

Cortex

where ground tissue is outside of the vascular tissue

Pith

where ground tissue occurs internal to vascular bundles, toward the center of the plant relative to vasculature

Root cap

an external layer of cells that protects the apical meristem at the root tip

Root hair

extensions of root cells cell walls and cytoplasm that reach out into the soil and increase surface area

Stele

column of vascular tissue in the center of a root (important in branching)

Pericycle

layer of cells outside the stele that doon’t normally divide, but can:

• create a new meristem that becomes the apical meristem of a new lateral root

Elongation zone

where newly formed cells increase in length, lengthening the root

Quiescent center

cells in the middle of the root’s apical meristem that do not actively divide, but can if errors from cell division happen → will rebuild the meristem

Differentiation zone

cells in this zone no longer grow or elongate, but instead mature in a functional root cell taking up water and minerals

Central zone

protects developing shoot from damage by taking over cell division in case of genetic errors

cells divide very slowly in this zone to reduce risk of propagating mutations

Leaf primordium

embryonic leaves that are created from meristematic cells flanking the apical meristem

Lateral meristem

cells that are completely different from the apical meristem - responsible for secondary growth (thickness)

made up of vascular cambium and cork cambium

Vascular cambium

generates the secondary xylem and phloem

Cork cambium

contains meristematic cells that continuously replaces the epidermis fo the plant under secondary growth to allow it to increase in girth while still fulfilling the role of the old dermal tissue → allows the vascular cambium to do its job

Water potential

a way of quantitatively describing water’s tendency to move form one place to another in energetically favorable water

(+) = more energy that water will have to move elsewhere

(-) = the less tendency water will have to move elsewhere

Hydrostatic pressure (Turgor pressure)

the pressure exerted by fluid inside the plant, which is caused by osmosis

Water potential equation

Ѱ = Ѱp + Ѱs

Pressure potential

<0 when more water is pumped into a system

>0 when water is pumped out of a system

Solute potential

water will move from a side with less solute and lower solute concentration to the side with more solute and higher solute concentration

more solute = more negative solute potential

not possible to have a positive solute potential