Exam 3 Study Guide Questions

What are the functions of roots, stems, and leaves, and examples of their modifications?

Roots anchor and absorb water/nutrients; stems support and transport; leaves perform photosynthesis. Examples include prop roots, rhizomes, and tendrils

What root tissue gives rise to lateral roots, and what produces root hairs?

Lateral roots arise from the pericycle; root hairs from the epidermis

What is the correct sequence of zones in primary growth of a root, moving upward from the root cap?

Zone of cell division → Zone of elongation → Zone of differentiation

Describe primary and secondary growth and list the meristems involved.

Primary growth increases length (via apical meristems); secondary growth increases thickness (via vascular cambium and cork cambium)

What tissue makes up the wood of a tree?

Secondary xylem

What is the bark of a tree trunk made up of?

Secondary phloem and periderm (cork + cork cambium)

What is the difference between heartwood and sapwood, and what are they comprised of?

Heartwood is dead inner xylem that no longer conducts water; sapwood is outer xylem that conducts water and minerals

Do monocots have apical meristems? Do they have lateral meristems?

Monocots have apical meristems for primary growth but lack lateral meristems (no vascular or cork cambium) for secondary growth

What structural components make up a virus, and how do they relate to its classification?

Viruses are made of nucleic acid and a protein coat, sometimes with a membranous envelope; they are classified by their type of genetic material

Compare the lytic and lysogenic cycles of bacteriophages. Which statement is true?

In the lytic cycle, the host cell is destroyed; in the lysogenic cycle, the viral DNA integrates into the host genome as a prophage

What is a key feature of a virulent phage?

It reproduces through the lytic cycle, leading to host cell lysis

Describe how a retrovirus replicates within a host. What enzymes are involved?

Retroviruses use reverse transcriptase in the cytoplasm to convert RNA into DNA, which integrates into the host genome with integrase

What are prions, and why are they unique compared to viruses?

They are infectious proteins that cause brain disease and lack nucleic acids

What is the difference between a prophage and a provirus?

A prophage is viral DNA integrated in bacterial DNA; a provirus is viral DNA integrated in eukaryotic DNA

Compare and contrast prokaryotic and eukaryotic cells. Which statement is correct?

Prokaryotes lack a nucleus and membrane-bound organelles, while eukaryotes have both

How do Gram-positive and Gram-negative bacteria differ structurally and functionally

Gram-positive bacteria have thick peptidoglycan walls; Gram-negative bacteria have thinner walls and an outer membrane that may be toxic

What processes contribute to genetic variation in prokaryotes?

Rapid reproduction, mutations, and genetic recombination

Describe the three mechanisms of genetic recombination in prokaryotes. Which set correctly identifies them?

Transformation, transduction, and conjugation

What roles do fimbriae, pili, and flagella play in bacterial life?

Fimbriae allow attachment, pili transfer DNA, and flagella provide motility

What are extremophiles?

Organisms that live in extreme environments such as high salinity or temperature

What is an endospore, and why is it important for bacterial survival?

A dormant, tough cell that allows bacteria to survive harsh conditions

Explain the importance of endosymbiosis in eukaryotic evolution, focusing on the evolution of mitochondria and plastids such as chloroplast.

Mitochondria originated from a bacterium engulfed by an archaeal cell, and plastids later evolved from a cyanobacterium engulfed by a heterotrophic eukaryote

What are the different roles of protists in ecological communities?

Protists include symbionts, producers, and parasites that influence both aquatic and terrestrial ecosystems

List and describe the major structural features of a fungus

Hyphae that form a mycelium, which increases surface area for nutrient absorption

List and describe the steps of a generalized life cycle of fungi (both sexual and asexual)

Fungi alternate between diploid and haploid multicellular stages through meiosis and mitosis; sexual reproduction involves plasmogamy, karyogamy, and meiosis

What is a lichen and what are the components of a lichen?

A symbiotic association between a fungus and a photosynthetic partner such as algae or cyanobacteria

What is the only type of algae that shares characteristics with land plants, and what are those characteristics?

Charophytes; rings of cellulose-synthesizing proteins, structure of flagellated sperm, and formation of a phragmoplast

What were the benefits and challenges faced by early plants as they made the move onto land?

Benefits: more CO₂ and sunlight; Challenges: desiccation, lack of structural support, radiation

Which of the following lists the derived traits of land plants?

Alternation of generations, multicellular embryos, walled spores, multicellular gametangia, apical meristems

What is alternation of generations?

A life cycle alternating between haploid gametophyte and diploid sporophyte stages

During alternation of generations, which generation produces gametes and which produces spores?

Gametophyte produces gametes by mitosis; Sporophyte produces spores by meiosis

Why do mosses require wet conditions to reproduce?

Their sperm are flagellated and must swim to reach eggs

What are key characteristics of ferns and other seedless vascular plants?

Dominant sporophyte generation, vascular tissue (xylem and phloem), flagellated sperm

What is the function of xylem and phloem?

Xylem transports water/minerals; phloem transports sugars/organic nutrients

What are sporophylls?

Leaf-like organs that bear sporangia

What is the difference between homosporous and heterosporous plants?

Homosporous plants produce one type of spore; heterosporous produce microspores and megaspores

What are the parts of a seed?

Embryo, food supply, and protective seed coat

What are the advantages of producing seeds?

Seeds allow dormancy, protection, and nutrient supply for the embryo

Which of the following are unique characteristics of seed-producing plants?

Reduced gametophytes, heterospory, ovules, and pollen

What is an ovule?

A structure that includes the megasporangium, megaspore, and one or more integuments

What is a pollen grain, and what cells does it contain?

The male gametophyte containing a generative cell (forms sperm) and a tube cell (forms pollen tube)

What is pollination?

The transfer of pollen to the part of a seed plant containing the ovules

What are reproductive adaptations unique to angiosperms?

Flowers and fruits

What are the main flower parts of a generalized flower?

Sepals, petals, stamens, and carpels

What is the order of floral organs from outside to inside?

Sepals → Petals → Stamens → Carpels

In a typical angiosperm, what sequence does a growing pollen tube follow to reach the egg?

Stigma → Style → Ovary → Ovule

What are fruits, and how are different types formed?

Fruits are mature ovaries that protect and aid seed dispersal; simple, aggregate, multiple, or accessory depending on floral origin

What is the purpose of fruit?

Protection and dispersal of seeds

What cells make up the embryo sac of an angiosperm?

Egg cell, synergids, antipodal cells, and central cell with two polar nuclei

What are the products of double fertilization in angiosperms?

Zygote (2n) and endosperm (3n)

How can monocots and dicots be distinguished?

Monocots have parallel leaf veins, fibrous roots, and floral parts in multiples of three; dicots have net-like veins, taproots, and floral parts in fours or fives