Biology 112 Exam 3

Plants

Green algae are the closest living relatives of land plants

Evidence is similarities in:

  • Chloroplast structure

  • Thylakoids

  • Cell walls

  • Peroxisomes

Major Land Plant Groups

  1. Non-vascular Plants

    • First to colonize terrestrial earth

    • Adaptations:

      • Cuticle: prevents water loss

      • Stomata: gas exchange for photosynthesis

      • UV protection

    • Don’t have vascular tissue

    • Example:

      • Mosses

  2. Seedless Vascular Plants

    • First large land based plant

    • Possess vascular tissue for nutrient and water transport

      • Xylem: water and minerals, one way flow

      • Phloem: water and nutrients, two way flow

    • Example:

      • Ferns

  3. Seed Plants

    • Have both gymnosperm and angiosperm

      • This enables survival in diverse environments

      • Seeds allow for better survival by helping with dispersal, nutrient storage, and embryo protection

    • Pollen → male gametophyte

    • Ovary → female gametophyte

  4. Flowering/Fruiting plants

    • Angiosperm

    • Adaptations like flowers and fruits promote reproduction by attracting pollinators and protect seeds

      • Flower ovaries form fruits

    • Fruits aid in the protection and dispersal of seeds

Gymnosperm → non-flowering, naked seed

Angiosperm → flowering, fruit providing

Plant Life Cycles

The cycle of gametophyte dominant (haploid) to sporophyte dominant (diploid) beneficial because:

  • Increases genetic diversity

  • Increases adaptability

  • Makes dispersal and reproduction more efficient

  • Seed (sporophyte) aids in protection and survival through hard conditions

  • Less reliance on water (gametophyte stage → pollen fertilization) allowing for life in diverse ecosystems

Water reliant reproduction → non-vascular plants, seedless plants

Non water reliant reproduction → seed plants, asexual reproduction

Important Structures:

Pollen:

  • Enables fertilization without the need for water facilitating reproduction in drier environments

  • Diversifies ecosystems

  • Increases survival

Seeds

  • Contain embryos, nutritional reserves, and protective coatings

  • Increases survival

  • Allows for more dispersal

Pollinators

  • Key for the reproduction of many flowering plants

  • Aids in fertilization without water

Flowers

  • Evolved to attract pollinators

  • Aids in sexual reproduction

Fruit

  • Protects seeds

  • Aids in seed dispersal by attracting animals

Plant Forms

Plants require light, CO2, water, and nutrients for growth

Shoot system

  • Above ground

  • Consists of stems and leaves

  • Facilitates photosynthesis and reproduction

Root system

  • Below ground

  • Anchors plants

  • Absorbs water and nutrients

High Surface Area/Volume ratio is high efficiency in exchange of materials

Phenotypic Plasticity:

  • Allows plants to adapt morphologically to environmental conditions

    • When soil is nutrient poor carnivorous structures form in some plants to capture nutrients

    • When in a shady environment plants grow larger leaves to capture more sunlight

Plant Nutrition

Nitrogen Fixation

  • Symbiotic bacteria convert atmospheric nitrogen into a usable form for plants

Parasitic Plants

  • Obtains nutrients directly from their host plants

Carnivorous Plants

  • Adaptations to trap and digest insects for additional nutrients in nutrient-poor environments

Animals

Multicellularity

  • Organized into complex tissues and structures

Heterotrophs

  • Obtain nutrients and energy from other organisms

Motility

  • Animals have to move at some point in their life cycle

  • Special structures:

    • Limbs

    • Muscles

    • Cilia

    • Flagella

Neurons and Muscle Cells

  • Most animals (excluding sponges) exhibit these traits

  • Movement and response to stimuli

  • Nervous system

Sponges 1st Hypothesis

Sponges are the earliest surviving branch of the animal tree

Proof:

  • Similarities with sister group to animals “choanoflagellates”

  • Earliest animal to appear in fossil group

  • They have the tool-kit genes

    • All animals have the starter pack DNA sequence that are important for development and multicellularity in animals

Embryonic Tissue Layers

Diploblasts → ectoderm and endoderm

Triploblasts → ectoderm, endoderm, and mesoderm

Layers (outside to inside):

  • Ectoderm:

    • Central nervous system

    • Outer epithelium of body surface

  • Mesoderm:

    • Muscle

    • Bone

    • Visceral organs

  • Endoderm:

    • Inner lining of digestive organs

    • Trachea

    • Lungs

Body symmetry

Asymmetry:

  • No symmetry

  • Ex: sponges

Radial symmetry:

  • Multiple planes of symmetry

  • Symmetry any way you slice it

  • Oral and aboral sides

  • Ex: jellyfish, starfish

Bilateral symmetry:

  • Divides body into along sagittal plane

    • Left and right halves

    • Leads to cephalization (highly specialized brain)

      • Key to developing nervous system and sensory organs

        • Taste

        • Temperature

        • Touch

          • Better predation

The Coelom

Tube within a tube

Acoelomate:

  • No body cavity

  • Just ectoderm, mesoderm, endoderm, digestive cavity (in that order from outside to inside)

True Coelomate:

  • Body cavity within the mesoderm (two half moons)

Pseudocoelomate:

  • Has a body cavity between mesoderm and endoderm

  • Ectoderm, BODY CAVITY (pseudocoel), mesoderm, endoderm, digestive cavity

Diversification of Feeding

Feeding strategies vary among the roles:

  • Detritivores

    • Decomposes, recycles

  • Herbivores

    • Eats plants

  • Carnivores

    • Eats other animals

  • Omnivores

    • Eats everything

Reproduction

Where does fertilization occur:

  • Asexual

    • Budding

      • Organism develops from bud o plant

    • Parthenogenesis

      • Development of egg into individual without fertilization

      • Usually a last resort option

  • Sexual

    • Internal fertilization

      • Fertilization happens inside the body

        • PRO’S

          • Protection of gametes

          • Higher fertilization success rate

        • CON’S

          • Higher energy consumption

    • External fertilization

      • Fertilization happens outside the body

        • PRO’S

          • Less energy consumed due to lack of parental care

          • More genetic diversity

        • CON’S

          • Less protection for gametes

Where does the embryo develop:

  • Oviparous (internal fertilization)

    • Embryo develops into eggs outside body

      • PRO’S

        • Lays multiple eggs at once

      • CON’S

        • Vulnerable to environment and/or predators

  • Ovoviviparous

    • Embryo develops into an egg inside the mom’s body

      • PRO’S

        • Safer for embryo compared to oviparous

      • CON’S

        • Limited space for multiple offspring

  • Viviparous

    • Embryo develops within mother

    • Embryo receives direct nourishment

      • PRO’S

        • More protection for embryo

      • CON’S

        • High energy cost for mom

Protostomes

Mouth forms 1st, anus forms 2nd

Blastopore develops into the mouth

Transition from water to land

Challenges:

  • Desiccation (loss of water)

  • Respiration

  • Movement

Adaptation:

  • High Surface Area/Volume ratio

    • Efficient gas exchange

  • Cuticle

    • Prevents water loss

  • Spiracles/trachea

    • Allows for gas exchange in terrestrial arthropods (insects) without water

  • Desiccation resistant eggs

    • Protects embryos from drying out

Arthropods

Most abundant animals on earth

Key traits

  • Segmented bodies plans for specialization

  • Protective exoskeleton

  • Jointed appendages that enhance movement

Why are insects so diverse:

  • Wings

    • Less predation

      • Better chance to reproduce

    • Migration to new niches

  • Plant eating

    • Plants are abundant

      • Ensures survivability

  • Co-evolved with angiosperms

    • Mutualism led to diversification

    • Plants becoming more diverse so predators adaptability increases so predator (insect) evolves more

Deuterostomes

Anus forms 1st, mouth forms 2nd

Blastopore develops into the anus

3 Phyla

  • Echinoderms

  • Hemichordates

  • Chordates

Chordates

  • Pharyngeal gill slits

    • For vertebrate fish

      • Develops into gill support

    • Tetrapods (4 limbed vertebrate)

      • Develops into parts of the ears and tonsils

  • Notochord

    • Flexible rod shaped structure that runs along the nerve cord

    • In vertebrates

      • Develops into the vertebrae

  • Muscular post-anal tail

  • Dorsal hallow nerve cord

    • In vertebrates

      • Develops into the spinal cord

Vertebrates

Key traits

  • Vertebrae

  • Cranium

Dominant group

  • Ray-finned fish

Amphibians

  • Jaws

  • Lungs

  • Limbs and not Lobed fins

Reptiles

  • Amniotic eggs

  • Scales

Mammals

  • Fur

  • Lactation

  • Placenta

  • Parental care

Mammals

Monotremes

  • Lay eggs

Marsupials

  • Give birth to underdeveloped young who continue to develop in the pouch

Eutherians (placental)

  • Mammals give birth to fully developed young

  • Nourishment in the placenta

Prokaryotes

Bacteria & Archaea

  • Different lipids in their plasma membranes

  • Different molecules for support in their cell walls

  • They can be both autotroph or heterotroph

  • Extremophiles

    • Archaea survive better in extreme environments

Importance

Biologically

  • They are the base of some food webs because of their abundance

Medically

  • Koch’s germ theory

Virulence

  • Ability to cause disease

  • Some species can have virulent and non-virulent (harmless) strains

Microbiome

  • Community of microbes that naturally inhabit body parts of body

Bioremediation

  • Use of microbes to clean contaminated soil or ground water

Protists

They don’t fit exclusively into the plant, animal, or fungi kingdom

They are important primary producers

  • They produce energy through photosynthesis

  • Ex: algae, phytoplankton

Can cause human diseases

Studied in medical industries

Ecological role

  • Primary producers

  • Sometimes decomposers

  • Carbon cycles in aquatic ecosystems

    • Converts carbon dioxide into organic matter

Fungi

Eukaryotes

  • More closely related to animals than plants

Heterotrophs

Can be parasitic

Decomposers

  • Absorbs nutrients from dead animals

Used in

  • Antibiotics

    • Treating bacterial infections

  • Carbon cycling

    • Helps release carbon back into the atmosphere

  • Mutualism

    • With plants