Plant Biology Exam Review: Seeds, Flowers, Transport, and Growth

Which group of plants were the first to have seeds?

Gymnosperms.

How are gymnosperm seeds different from angiosperm seeds?

Gymnosperm seeds are 'naked' — not enclosed in fruit.

When were gymnosperms most abundant and dominant?

During the Mesozoic era (especially Jurassic).

What are the four groups of gymnosperms?

Cycads, Ginkgo, Gnetophytes, Conifers.

Which gymnosperm group has the most species today?

Conifers.

Where are cycads found today?

Tropical and subtropical regions.

How many species of Ginkgo exist today?

Only one: Ginkgo biloba.

Which gymnosperm has the longest leaves?

Cycads (some species).

If people collect seeds to eat, which gymnosperm is it usually from?

Pine trees (pine nuts).

Where are reproductive structures found in conifers?

In cones (male pollen cones & female seed cones).

How is pollination achieved in conifers?

Primarily by wind.

What are examples of conifers in Wisconsin?

Fir, pine, cedar.

Which conifer sheds its leaves in winter?

Tamarack (larch).

What are the main parts of a dicot flower?

Sepals, petals.

Where is pollen found?

In the anthers.

Flowers evolved from what structures?

Modified leaves.

How is self-pollination prevented?

Self-incompatibility (genetic recognition).

What is buzz pollination?

Bees vibrate anthers to release pollen.

What species exhibit buzz pollination?

Tomatoes, blueberries, cranberries.

What is unique about milkweed pollination?

Pollen is in pollinia (sticky sacs) that attach to insects.

How do bats pollinate plants?

They visit night-blooming flowers for nectar and transfer pollen on their fur.

What is the first step of double fertilization?

Pollen tube delivers two sperm to the ovule.

What is the second step of double fertilization?

One sperm fertilizes the egg → zygote.

What is the third step of double fertilization?

Other sperm fuses with two polar nuclei → endosperm (nutritive tissue).

What are ways seeds are dispersed?

Wind.

What are the main identifying features of angiosperm phylogeny?

Flowers.

What is a phytometer?

A plant used to measure environmental conditions (e.g., soil nutrients).

How is plant growth different from animals?

Plants grow continuously from meristems.

What is indeterminate growth?

Growth that continues throughout life.

What are the three tissue types in plants?

Dermal, ground, vascular.

What does dermal tissue give rise to?

Epidermis, protective outer layer.

What does ground tissue give rise to?

Parenchyma, collenchyma, sclerenchyma.

What does vascular tissue give rise to?

Xylem and phloem.

What is the function of parenchyma?

Photosynthesis, storage, regeneration.

What is the function of collenchyma?

Flexible support in young stems/leaves.

What is the function of sclerenchyma?

Rigid support; thick lignified walls.

What is the function of xylem?

Transports water and minerals upward.

What is the function of phloem?

Transports sugars throughout plant.

What is the function of tracheids?

Water transport; tapered cells.

What is the function of vessel elements?

Efficient water transport; wide tubes.

What is the function of companion cells?

Support sieve tube elements; metabolic help.

What is the function of sieve tube elements?

Conduct sugars in phloem.

Where are stomata found?

Mostly on underside of leaves.

What are the products of light reactions?

ATP, NADPH, O₂.

What are the products of the Calvin cycle?

G3P (sugar precursor).

Why doesn't the Calvin cycle occur at night?

Requires ATP & NADPH from light reactions.

What is the difference between C3 and C4 plants?

C4 plants separate carbon fixation spatially to reduce photorespiration.

How do CAM plants reduce water loss?

Open stomata at night; store CO₂ as malate.

What percentage of absorbed water is lost by transpiration?

About 95-99%.

How does CO₂ enter plants?

Through stomata.

Which plant parts form potatoes and onions?

Potatoes = modified stems (tubers). Onions = modified leaves (bulbs).

What are primary meristems responsible for?

Length growth (apical meristems).

What are secondary meristems responsible for?

Width growth (vascular & cork cambium).

What is the difference between primary and secondary growth?

Primary = elongation; Secondary = thickening.

What is primary growth in plants?

Elongation of stems and roots.

What is secondary growth in plants?

Thickening of stems and roots.

What does dermal tissue differentiate into?

Epidermis, guard cells, root hairs.

What does ground tissue differentiate into?

Parenchyma, collenchyma, sclerenchyma.

What does vascular tissue differentiate into?

Xylem and phloem.

How did one gene change teosinte into corn?

Changes in gene tb1 increased branching suppression.

What led to larger kernels in corn?

Changes in gene tb1 led to larger, exposed kernels and domesticated traits.

What creates growth rings in trees?

Seasonal changes in xylem cell size (early vs late wood).

What contributes most to plant dry weight?

Carbon fixed from CO₂ during photosynthesis.

What is the vascular arrangement in dicot shoots?

Vascular bundles in a ring.

What is the vascular arrangement in monocot shoots?

Vascular bundles scattered.

What is the vascular arrangement in dicot roots?

X-shaped xylem in center; phloem between arms.

What is the vascular arrangement in monocot roots?

Central pith with ring of xylem/phloem around it.

What are arbuscular mycorrhizae?

Fungal hyphae penetrate root cells; form arbuscules.

What are ectomycorrhizae?

Fungi surround root surface; do not enter cells.

What did Simard's experiment show about trees?

Trees transfer carbon through fungal networks.

What can different species do underground according to Simard's experiment?

Different species can share resources.

Why was cedar included in Simard's experiment?

Cedar does not form mycorrhizae → used as a control.

What are macronutrients?

Nutrients needed in large amounts (e.g., N, P, K).

What are micronutrients?

Nutrients needed in small amounts (e.g., Fe, Zn, Cu).

How do plants obtain ions stuck to clay?

Root hairs release H⁺ to displace cations (cation exchange).

How does water move from roots to leaves?

Through root pressure and cohesion-tension mechanism via transpiration pull.

What is the apoplast pathway?

Water moves through cell walls & spaces, not cytoplasm.

What is the symplast pathway?

Water moves through cytoplasm via plasmodesmata.

Why does sap flow only in early spring?

Freeze-thaw cycles create pressure changes in xylem.

Why does maple sap taste different later in the season?

More microbial activity & metabolic changes alter sugar composition.

What drives transpiration pull?

Evaporation of water from leaf surfaces.

Why is cohesion important in water transport?

Water molecules stick together, forming a continuous column.

Why is adhesion important in water transport?

Water sticks to xylem walls, helping resist gravity.

What prevents air bubbles from spreading in xylem?

Pits between tracheids/vessel elements.

Why does sap rise during freeze-thaw cycles?

Freezing draws water into xylem, creating suction.

What happens during thawing in freeze-thaw cycles?

Increases pressure, pushing sap upward.

Why do roots release CO₂ into soil?

CO₂ forms carbonic acid → releases ions from clay.

Why do root hairs increase nutrient uptake?

Large surface area for absorption.

What is a unique angiosperm trait regarding vessels?

Most angiosperms have vessel elements for efficient water transport.

What is a unique angiosperm trait regarding fruits?

Fruits protect seeds and aid dispersal.

What are traits of wind-pollinated flowers?

Small, no petals, lots of pollen.

What are traits of animal-pollinated flowers?

Colorful, scented, nectar present.

Why do some flowers open only at night?

Adaptation to nocturnal pollinators (e.g., bats, moths).

What is animal internal seed dispersal?

Seeds survive digestion and are excreted elsewhere.

What is animal external seed dispersal?

Seeds stick to fur or feathers.

What is an example of mechanical seed dispersal?

Touch-me-not seed pods exploding.

Why do C3 plants photorespire?

Rubisco binds O₂ when CO₂ is low.

How do C4 plants avoid photorespiration?

Use PEP carboxylase, which doesn't bind O₂.

Why do CAM plants open stomata at night?

Reduces water loss in hot, dry environments.

What is the function of the cuticle?

Reduces water loss.