BIOL 1P92 Final (Prof Study Questions)
Week 7: What Characteristics Distinguish plants from their algal ancestors?
- plants are multicellular, have plastids, and primarily live on land, whereas algaue are mostly aquatic
Wk 7: What key adaptations allowed plants to survive on land?
development of a cuticle to prevent water loss, stomata for gas exchange, and structures like vascular tissue for support and transport
Wk 7: What is the significance of plastids in plant cells?
plastids, including chloroplasts, are responsible for photosynthesis and other biosynthetic processes
wk 7: How do land plants differ from their closest green algal relatives?
- land plants have multicellular tissues, alternation of generations, and specialized reproductive structures like gametangia
Wk 7: From which group of algae did land plants evolve?
land plants evolved from streptophyte algae that were similar to Charophycean algae
Wk 7: What is the haploid-dominant (zygotic) life cycle, and in which organisms is it found?
- it is a reproductive cycle where the haploid stage dominates, found in some algae
What is alternation of generations, and how does it differ from the zygotic life cycle?
- alternation of generations includes both multicellular haploid (gametophyte) and diploid (sporophyte) stages, unlike the zygotic cycle where the diploid phase is brief.
How do gametophytes function in plant reproduction?
- gametophytes produce haploid gametes through mitosis, which then fuse to form a diploid zygote
What structures protect plants gametes from desiccation?
- Gametangia (antheridia for sperm and archemonia for eggs) protect gametes
wk 7: What are the main differences between gametophytes and sporophytes?
- Gametophytes are haploid and produce gametes, while sporophytes are diploid and produce spores
Wk 7: What are the nine major phyla of plants?
Hepatophyta (liverworts)
Bryophyta (mosses)
Anthocerophyta (hornworts)
Lycophyta (lycophytes)
Pteridophyta (ferns)
Cycadophyta (cycads)
Ginkgophyta (ginkgos)
Coniferophyta (conifers)
Anthophyta (angiosperms)
What traits distinguish bryophytes from other plant groups?
They lack vascular tissue, have dominant gametophytes, and require water for sperm moveme
Wk 7: Why are bryophytes typically found in mois environments?
They need water for reproduction since their sperm are flagellated and require water to swim to the
egg
Wk 7: What adaptations do bryophytes have for reproduction?
They produce spores with tough walls, rely on water for fertilization, and have protective gametangia
Wk 7: How do liverworts differ from mosses and hornworts?
- liverworts lack true stomata, whereas mosses and hornworts possess them
Wk 7: What is the role of rhizoids in bryophytes?
Rhizoids anchor the plant and aid in water absorption, but they do not function like true roots
Wk 7: What is the significance of vascular tissue in plants?
Vascular tissue (xylem and phloem) transports water, nutrients, and food, allowing plants to grow large
How do lycophytes differ from pteridophytes?
Lycophytes have microphylls (small leaves with a single vein), while pteridophytes have megaphylls (larger leaves with multiple veins
What features define seedless vascular plants?
They possess vascular tissue but reproduce via spores instead of seeds
How do lycophytes transport water and nutrients?
- they use vascular tissue, specifically xylem for water transport and phloem for nutrient distribution.
Wk 7: What are tracheophytes, and what adaptations do they have for land?
Tracheophytes are plants with vascular tissue, enabling efficient water transport and structural support
Why were lycophytes and pteridophytes more abundant in the past?
They dominated Carboniferous forests, forming vast swampy ecosystems, but declined as climate changed
What structures in ferns house spores?
Spores are housed in sporangia, often grouped into clusters called sori
How do the sporophyte and gametophyte stages differ in ferns?
The sporophyte is the dominant stage, while the gametophyte is small and free-living
Wk 7: What role do sori play in fern reproduction
Sori contain sporangia that produce spores for reproduction
What climat changes during the Carboniferous period led to the dominance of gymnosperms
- cooler and drier conditions caused the decline of lycophytes and pteridophytes, allowing gymnosperms to diversify
What are the four major groups of gymnosperms?
Cycadophyta (cycads), Ginkgophyta (ginkgoes), Coniferophyta (conifers), and Gnetophyta
(gnetophytes)
Why are gymnosperm seeds called "naked seeds"?
they are not enclosed by fruit, unlike angiosperm seeds
What reproductive adaptations do gymnosperms have
- they produce seeds and pollen, allowing fertilization without water
What are some common characteristics of conifers?
- needle-like leaves
- produce cones
- many are evergreen
Wk 7: What is the main advantage of seeds over spores?
Seeds provide protection, nourishment, and can remain dormant until favourable conditions
arise.
How do ovules develop into seeds
after fertilization, the ovule matures into a seed containing an embryo, nutritive tissue, and a protective seed coat.
What is heterospory, and how is it beneficial?
The production of two types of spores (microspores and megaspores) increases cross-fertilization and genetic diversity
What is the function of a pollen tube?
- it delivers sperm directly to the egg, eliminating the need for water in fertilization
How do gymnosperms disperse their seeds
seeds are dispersed by wind, animals, or other environmental factors
what distinguishes angiosperms from gymnosperms
- angiosperms have flowers and fruits, which protect and aid in seed dispersal
what are the two major groups of angiosperms
Monocots (one cotyledon) and eudicots (two cotyledons
How do flowers contribute to angiosperm success?
they attract pollinators, increasing reproductive efficiency and genetic variation
What role does endosperm play in angiosperm seeds
it provides nutrients for the developing embryo
What is double fertilization in angiosperms
One sperm fertilizes the egg (forming an embryo), while the other forms the triploid endosperm
How do fruits aid in seed dispersal
fruits attract animals, who eat and spread seeds, or use wind/water for dispersal
What are some key differences between monocots and eudicots
monocots have parallel-veined leaves, while eudicots have net-veined leaves
What adaptations allow angiosperms to transport water efficiently?
they have vessel elements in their xylem, which are more efficient than tracheids
How have angiosperms co-evolved with pollinators?
- specific flower traits attract certain pollinators, increasing fertilization success
Why is seed dormancy an important adaptation?
- it allows seeds to survive unfavourable conditions and germinate at the right time
Wk 7: How did early land plants contribute to atmospheric changes?
they increased oxygen levels and helped develop soil
What is placental transfer tissue, and why is it significant?
- it allows maternal tissues to nourish developing embryos, an important evolutionary step
Why was the origin of land plants crucial for animal colonization?
plants provided oxygen and food, making land habitale for animals
How did gymnosperms and angiosperms shape modern ecosystems
- they dominate forests, influence climate, and support diverse life forms
What major advantage do angiosperms have over gymnosperms?
- more efficient reproduction via flowers, fruits, and diverse pollination strategies
Wk 8: From what type of ancestor did animals evolve?
animals evolved from a protist similar to choanoflagellates
Wk 8: What are choanoflagellates, and why are they important?
They are single-celled protists with a flagellum surrounded by a collar of tentacles. They are the closest living relatives of animals and resemble sponge choanocyte
What are the defining characteristics of animals?
- multicellular, heterotrophic, lack cell walls, motile at some stage, and reproduce sexually or asexually
What structural component provides support in animals
- the extracellular matrix (ECM), composed mainly of collagen
What types of cell junctions are unique to animals?
anchoring, tight, and gap junctions
What are the three main modes of animal feeding?
Suspension feeding (filtering particles from water)
bulk feeding (eating large food pieces),
fluid feeding (sucking sap or body fluids)
Why is movement important for animals?
It helps in food acquisition, escaping predators, and finding mate
What type of tissue is unique to animals?
Muscle tissue, which allows for movement
How do sessile animals, such as barnacles, adapt to movement?
- they have moving appendages or a mobile larval stage
What is cephalization, and why is it important?
Cephalization is the concentration of sensory and nervous structures at the anterior end of the body, allowing better coordination and response to stimuli
How do most animals reproduce?
Most animals reproduce sexually, with small, mobile sperm fertilizing a larger egg to form a zygote.
What is the difference between internal and external fertilization?
internal fertilization occurs inside the female body, while external fertilization occurs in water
What is metamorphosis, and why is it beneficial?
metamorphosis is a developmental change from juvenile to adult form (e.g. tadpole to frog)
- reduces competition and aids in dispersal
Wk 8: What role do Hox genes play in animal development?
Hox genes control body patterning along the anterior-posterior axis
What is the significance of the Cambrian explosion
- It was a rapid increase in animal diversity (~533-525 million years ago), leading to the appearance
of most major animal group
What are the three embryonic germ layers?
Endoderm (forms the gut lining)
mesoderm (forms muscles and organs)
ectoderm (forms the skin and nervous system)
What is the difference between diploblastic and triploblastic animals?
Diploblastic animals have two germ layers (ectoderm and endoderm), while triploblastic animals have all three (including mesoderm)
What are the two types of body symmetry in animals?
Radial symmetry (e.g., jellyfish) and bilateral symmetry (e.g., human
What is the advantage of bilateral symmetry?
It allows for cephalization and more efficient movement
What are the terms used to describe body orientation in bilaterally symmetrical animals?
Dorsal (back), ventral (front or belly), anterior (head), and posterior (tail)
What are the three types of body cavities in animals?
Acoelomates (no body cavity), pseudocoelomates (cavity not fully lined by mesoderm), and
coelomates (true coelom fully lined by mesoderm).
What is an example of an acoelomate animal?
Flatworms (Phylum Platyhelminthes).
What is an example of a pseuodocoelomate animal?
Roundworms (Phylum Nematoda).
Why is a coelom important?
It provides space for organ development and allows better movement and circulation
What evolutionary advantages helped animals diversify?
The development of tissues, body symmetry, cephalization, and body cavities allowed for greater complexity and adaptability
What are the two main groups of bilaterian animals based on embryonic development?
o Protostomes and deuterostomes
How do protostomes and deuterostomes differ in nervous system placement?
Protostomes have a ventral nervous system, while deuterostomes have a dorsal nervous system.
What is segmentation, and why is it important?
Segmentation is the repetition of body structures along the anterior-posterior axis. It allows for greater flexibility and specialization in movement
How has molecular data changes our understanding of animal phylogeny?
It has shown that some traditional traits, such as coelom type, are unreliable for determining evolutionary relationships
What are the two major invertebrate clades identified by molecular data?
Lophotrochozoa and Ecdysozo
Which phylum is considered the earliest group of animals?
Ctenophora (comb jellies)
What are the key characteristics of ctenophores?
They have eight rows of cilia for movement, two tentacles without stinging cells, and a complete gut with an anus
Why are ctenophores considered serparate from jellyfish despite their similar appearance?
Their nervous system and gut structure evolved independently from cnidarian
What are the main characteristics of sponges (Phylum Porifera)?
They lack true tissues, have porous bodies, and rely on choanocytes for filter feeding
How do sponges reproduce?
They reproduce both sexually (hermaphroditic fertilization) and asexually (budding or fragmentation)
What are the main characteristics of cnidarians?
- sac-like body with a single opening
- radial symmetry
- specialized tissues
- stingning nematocysts
What are the two main body forms found in cnidarians?
The polyp (sessile) and medusa (free-swimming) forms
What is the function of nematocysts in cnidarians?
Nematocysts are stinging organelles used to capture prey and for defense
What is an example of a cnidarian with a life cycle that alternates between polyp and medusa stages?
The moon jelly (Aurelia)
Wk 8: Why are cnidarians considered among the simplest animals with nervous systems?
• They have a nerve net instead of a centralized brain.
What are the defining characteristics of Lophotrochozoa?
They have either a lophophore (feeding tentacles) or a trochophore larval stage
What are the three main phyla in Lophotrochozoa?
Platyhelminthes (flatworms), Mollusca (mollusks), and Annelida (segmented worms
What is unique about flatworms (Platyhelminthes)?
• They lack a coelom, have a simple digestive system, and can regenerate body par
What is an example of a mollusk with a highly developed nervous system?
Cephalopods, such as octopuses and squids
What is segmentation in annelids, and how does it benefit them?
their bodies are divided into repeated segments, allowing for efficient movement and flexibility
What is the defining feature of Ecdysozoa?
They grow by molting (ecdysis), shedding their exoskeleton
Which two major phyla belong to Ecdysozoa?
Nematoda (roundworms) and Arthropoda (insects, spiders, crustaceans
What is the difference between the body cavities of roundworms and annelids?
Roundworms have a pseudocoelom, while annelids have a true coelom
Why are arthropods considered the most diverse animal phylum?
They have specialized body segments, exoskeletons, and adaptations for various environments
What is an example of an arthropod adaptation that led to their success?
The evolution of jointed appendages for movement and manipulation