Exam 3 Flashcards
Module 10-13 quizzes & outline notes
Which of the following structures is involved in the human knee-jerk reflex?
spinal cord
Which of the following results from increased activity in the sympathetic nervous system?
digestion is inhibited
Which of the following organisms demonstrates cephalization?
planarians
In which brain structure are circadian rhythms coordinated?
the hypothalamus
Which of the following controls balance and coordinates movements in humans?
the cerebellum
Emotional responses and memories are stored and recalled from which part of the brain?
the amygdala
Which part of the brain controls breathing, swallowing, vomiting, and digestion?
the medulla oblongata
Which brain region controls hand-eye coordination?
the cerebellum (V)
Which of the following regions arose developmentally from the hindbrain?
the medulla oblongata (III)
In which part of the brain are movement and balance coordinated?
the cerebellum
Which of the following functions is associated with Wernicke’s and Broca’s regions?
speech
Which part(s) of your brain are most involved in writing an essay?
frontal lobes
What was the consequence of a metal rod driven into the frontal lobe of Phineas Gage (with similar results to a frontal lobotomy)?
greatly altered emotional responses
What sense is most likely to be impaired by an injury to the temporal lobe?
hearing
What do we call the point of connection between two communicating neurons?
a synapse
In which brain structure does short-term memory information processing take place?
hippocampus
Which of the following describes a difference between bipolar disorder and schizophrenia?
schizophrenia typically involved hallucinations, not seen in bipolar disorder
What neurotransmitter is involved in schizophrenia, Parkinson’s disease, and drug addiction?
dopamine
Which of the following characteristics are associated with Alzheimer’s disease?
amyloid plaques and neurofibrillary tangles
Which of the following is true about the brain reward system?
It utilizes the neurotransmitter dopamine and is affected by drug addiction
Which of the following organisms were most likely the direct ancestors of plants?
green algae
What evidence do paleobotanists look for that indicates the movement of plants from water to land?
waxy cuticle to decrease evaporation from leaves
Which of the following biological molecules contributes to the structural integrity of plant spores?
sporopollenin
Gas exchange in most land plants occurs through structures called
the stomata
A growth-producing region of cell division, known as a ______, is found near the tips of stems and roots
apical meristem
In plants, the vascular tissue made of dead cells that transport water and minerals from the roots is called
xylem
In plants, the vascular tissue that consists of living cells that distribute sugars throughout the plant is called
phloem
Mosses belong to the group of plants known as the
bryophytes
Which of the following statements regarding ferns is true?
Ferns have well-developed roots & rigid stems
The majority of plant species today are
angiosperms
The type of life cycle seen in plants is called
alternation of generations
In cnidarians, what controls the contraction & expansion of the gastrovascular cavity?
A nerve net, interconnected nerve cells
What is cephalization?
the clustering of sensory neurons & interneurons at the anterior end
What do the CNS & PNS consist of?
The CNS is the brain & longitudinal nerve cords/spinal cord
PNS is nerves & ganglia
What do ependymal cells do?
line the ventricles & have cilia that circulate cerebrospinal fluid
What do oligodendrocytes & Schwann cells do?
axon myelination
What is the function of astrocytes?
-provide structural support for neurons
-regulate extracellular concentrations of ions & neurotransmitters
-facilitate information transfer at synapses
-induce cells that line capillaries in CNS to form tight junctions
What role do radial glia play in the nervous system?
form tracks along which newly formed neurons migrate from the neural tube, the structure that gives rise to the CNS
What in the nervous system can act as stem cells?
radial glia & astrocytes
What does the cavity of the nerve cord form in the spinal cord & brain? What is it filled with?
the central canal in the spinal cord & ventricles in the brain. Filled with cerebrospinal fluid.
What is the function of cerebrospinal fluid?
brings nutrients & hormones to the brain, clears waste, cushions the brain + spinal cord
What does grey matter & white matter consist of?
Grey matter consists of neuron cell bodies, dendrites, & unmyelinated axons
White matter contains bundled axons with myelin sheaths
Where can you find white matter and what does it do?
The outside of the spinal cord, linking the CNS to sensory & motor neurons of the PNS.
The inside of the brain, signaling between neurons in learning, emotion, sensory processing, and generating commands
Sensory info reaches the CNS along what neurons?
afferent PNS neurons
The 2 efferent components of the PNS
the motor system & automatic nervous system
What is the function of the sympathetic division?
arousal & energy generation
What are the physiological manifestations of the fight-or-flight response?
-increased heart rate
-liver converts glycogen to glucose
-digestion inhibited
-secretion of epinephrine from adrenal medulla is stimulated
What is the function of the parasympathetic division?
promote calming and return to self-maintenance functions (rest & digest)
What are the physiological manifestations of increased parasympathetic division activity?
lower heart rate, increased glycogen production, & enhanced digestion
What is the enteric division?
networks of neurons in the digestive tract, pancreas, and gallbladder that regulate secretion & peristalsis
What is the nervous systems response to a drop in body temperature?
the hypothalamus signals the autonomic nervous system to constrict surface blood vessels, reducing heat loss.
The hypothalamus also signals the somatic nervous system to cause shivering, increasing heat production
What activities are associated with the cerebrum?
calculation, contemplation, and memory
What activities are associated with the forebrain?
processing olfactory input, sleep regulation, learning, and complex processing
What is the function of the midbrain?
coordinating routing of sensory input
What activities are associated with the hindbrain?
involuntary activities like blood circulation & motor activities
Transitions in alertness, drowsiness, and sleep are regulated by which brain structure(s)?
the brainstem & cerebrum
What does the reticular formation control?
arousal & sleep- filters the information that reaches the cerebrum. The more info received, the more alert a person is.
Which parts of the brainstem regulate sleep?
the reticular formation, the pons, and medulla
Which animal swims while sleeping?
bottlenose dolphins
Which animals sleep with one brain hemisphere at a time?
dolphins
What is a biological clock?
a molecular mechanism that directs periodic gene expression & cellular activity. Synched to light-dark cycle, but roughly maintains 24-hour cycle regardless.
What are circadian rhythms coordinated by in mammals?
A group of neurons in the hypothalamus called the suprachiasmatic nucleus (SCN)
What is the function of the suprachiasmatic nucleus (SCN)?
It acts as a pacemaker, synching the biological clock in cells throughout the body to the natural cycles of day length
What brain structure(s) function in the generation and experience of emotions?
The amygdala, hippocampus, & parts of the thalamus (the limbic system)
What are the functions of the limbic system?
Emotion, motivation, olfaction, behavior, & memory
What brain structure plays the biggest role in storing emotional memory?
The amygdala
If the cerebrum were damaged, what activities may be effected?
awareness of surroundings, language, cognition, memory, & conciousness
What is the function of somatosensory receptors?
provide info about touch, pain, pressure, temperature, and position of muscles/limbs
How is sensory information directed in the cortex?
The thalamus directs inputs to primary sensory areas. Visual info to occipital lobe & auditory info to temporal lobe
What commands does the cerebral cortex generate?
Motor commands consisting of action potentials produced by neurons in the motor cortex. These travel along axons to the brainstem, spinal cord, through motor neurons, which excite skeletal muscle cells
Where in the brain are neurons that process sensory info from the legs & feet?
the midline of the somatosensory cortex
A tumor in the frontal lobe may result in what changes?
Retained intellect & memory, but diminished decision making & emotional response
Which cortex accounts for the most brain mass?
The cerebral cortex, with 80%
What is the neocortex?
The outermost part of the cerebral cortex, formed of six parallel layers of neurons tangential to brain surface
A defect in the Broca’s area may affect what behavior?
facial movement
Damage to what area of the brain would result in difficulty comprehending speech but not the ability to speak?
Wernicke’s area, in the left temporal lobe
Which lobes are activated when meaning must be attached to words?
Frontal & temporal areas
How is the concept of lateralization seen in human brain functioning?
The left hemisphere is more adept at logical operations while the right hemisphere is more adept at pattern recognition & nonverbal thinking
Which creatures possess a convoluted neocortex?
Primates & cetaceans (whales, dolphins, & porpoises)
Sophisticated information processing is located where in birds?
A clustering of nuclei in the pallium, the top/outer portion of the brain
How did the difference between the bird and human pallium arise during evolution?
A common ancestor had a pallium in which neurons were organized into nuclei, as is found in birds. In mammalian evolution, this was transformed into a layered arrangement of neurons.
How is the nervous system structure established during embryonic development?
through regulated gene expression, signal transduction, neuron competition, and synapse elimination
What is the process of synapse elimination in embryonic development?
A developing neuron forms many more synapses than required for proper function. Neuron activity stabilizes some synapses & destabilizes others. By the end of embryonic development, neurons have usually lost more than half of their initial synapses- leaving behind the connections that survive into adulthood
What is neural plasticity?
The nervous systems capacity to be remodeled in response to its own activity
How does the nervous system reshape itself?
Usually at synapses. Synapses with correlating activity are reinforced while synapses with less correlation become weaker
Which neurological divergence is characterized by a disruption of activity-dependent remodeling at synapses and what are the resulting behaviors?
Autism. Characterized by impaired communication and social interaction & stereotyped/repetitive behaviors
Where in the brain are short-term and long-term memories located?
Both involve storage in the cerebral cortex. Short-term is accessed via temporary links in the hippocampus
What would result from serious damage to the hippocampus?
Inability to form new lasting memories, but no change to event recall from before damage
What evolutionary advantage is offered by organizing short-term & long-term memories differently?
Long-term memories can be integrated into existing knowledge/experience. Transfer of info from short to long term memory is enhanced by the association of new & old data.
What activities prompt neurons to make new connections?
Learning skills & procedures, like riding a bike
What activities rely mainly on changes in the strength of existing neuronal connections?
Memorizing phone numbers, facts, and places
What is long-term potentiation (LTP) and how does it occur?
LTP is a lasting increase in the strength of synaptic transmission, involving a presynaptic neuron that releases glutamate. To occur, there must be a brief high-frequency series of action potentials in the presynaptic neuron that arrive at the synaptic terminal simultaneously as the postsynaptic cell receives a depolarizing stimulus
Which glutamate receptors are involved in LTP?
NMDA & AMPA
How does the mammalian CNS repair itself when damaged/diseased?
It cannot fully repair itself. Surviving neurons can make new connections & sometimes compensate, but damage/disease has irreversible effects
What are possible brain functions that cause schizophrenia symptoms?
Neuronal pathways that use dopamine & altered glutamate signaling. Amphetamines & PCP can produce the same symptoms.
Which brain region receives inputs to the reward system?
The ventral tegmental area (VTA) near brain base
What do the symptoms of Parkinson’s disease result from?
death of neurons in the midbrain that normally release dopamine at synapses in the basal nuclei
What is the closest relative to land plants?
charophytes
Plant characteristics
multicellular, eukaryotic, photosynthetic, autotrophs with cell walls & chloroplasts
Which characteristics do charophytes share with land plants?
- distinct rings of cellulose-synthesizing complexes that synthesize the cellulose microfibrils of cell walls
- peroxisome enzymes to minimize organic product loss in photorespiration
- flagellated sperm
- formation of a phragmoplast, group of microtubules between daughter nuclei of dividing cell
What function does sporopollenin serve for charophyte zygotes?
This durable polymer prevents exposed zygotes from drying out
What differentiates land plants from algae?
Alternation of generation, sporangia that produce walled spores, gametangia that produce gametes, and apical meristems
What is the process underlying alternation of generations in plants?
Multicellular gametophytes have haploid (1n) cells. They produce gametes, eggs, and sperm by mitosis. Fertilization forms a diploid (2n) zygote. Mitotic division of the zygote produces the sporophyte. Meiosis in mature sporophytes produce haploid (1n) reproductive spores. Mitotic division of spores produce new gametophytes.
What on the sporophyte produces spores?
sporangia
Within sporangia, what generates haploid spores?
sporocytes
Which plant structures produce eggs and sperm?
Archegonium, a female gametangium, produce egg & retain them in the base.
Antheridia, male gametangia, produce & release eggs into environment
What is present in the epidermis of many plant species?
A cuticle consisting of polyester & wax polymers, which acts as waterproofing. It acts as waterproofing, preventing water loss & protects against microbial attack
Early plants formed what symbiotic association with fungi?
Mycorrhizae. Extensive filaments in soil absorb nutrients & fungi transfer nutrients to symbiotic plant partner
Secondary compounds include what compounds? What is their function?
Alkaloids, terpenes, tannins, and phenolics. Bitter taste, strong odor, or toxic effect defends against herbivores and parasites Flavonoids absorb harmful UV radiation while other phenolics deter attack by pathogens.
What characterizes a vascular plant?
A complex vascular tissue system, cells joined into tubes that transport water & nutrients throughout the plant body.
2 clades representative of seedless vascular plants
Lycophytes, include club mosses
Pterophytes, include ferns
Which two groups are classified as seed plants and how do they differ?
Gymnosperms are “naked seed” plants because their seeds are not enclosed in chambers.
Angiosperms include all flowering plants. Seeds develop inside ovaries. Nearly 90% of plant species.
Which phyla represent nonvascular (bryophyte) plants?
Hepatophyta (liverworts), anthocerophta (hornworts), bryophyta (mosses)
Which life phase is the largest for bryophytes?
haploid gametophyte
What are the characteristic of protonema produced by moss spores?
A mass of green, branched filaments that are 1 cell think. Large surface area to enhance water & mineral absorption. Produces buds in favorable conditions
Why do bryophyte gametophytes form ground-hugging carpets?
Their bodies are too thin to support a tall plant. They lack vascular tissue. The thin structure allows for short distance material distribution without vascular tissue
What is the function of rhizoids?
The long, tubular single cells or filaments of cells serve to anchor gametophytes
What are the different segments seen in a bryophyte sporophyte?
A foot, embedded in the archegonium, to absorb nutrients. A seta, an elongated stalk, which transfers the nutrients to the sporangium. The sporangium, a capsule, uses nutrients to produce spores. In most mosses, the sporangium features a peristome, a ring of interlocking structures, which releases the spores.
What supports photosynthesis in hornworts and mosses?
The stomata
What are the characteristics of peat?
Organic materials resistant to decay due to phenolic compounds & acidic secretions. Often used as fuel and soil conditioner
What are three traits that characterize modern vascular plants?
Life cycles with dominant sporophytes (2n), transport in vascular tissue called xylem and phloem, well-developed roots and leaves including spore-bearing leaves (sporophylls)
What is the function of Xylem in vascular plants?
To conduct most of the water and minerals through their tracheids, tube shaped cells that carry materials up from roots
What strengthens the water-conducting cells in vascular plants?
The phenolic polymer lignin
What is phloem?
living tissue where nutrient-conducting cells are arranged into tubes that distribute sugars, amino acids, and other organic products
2 major leaf classifications
microphylls, small leaves with single unbranched vein seen in lycophytes
megaphylls, with a highly branched vascular system seen in all other vascular plants
How does sporophyll structure differ between ferns & lycophytes/gymnosperms?
Ferns produce clusters of sporangia called sori, usually on underside of sporophylls. In lychophytes & gymnosperms, groups of sporophylls form cone-like strobili
What adaptations contributed to the success of seed plants?
reduced gametophytes, heterospory, ovules, and pollen. Better strategies to cope with drought & UV radiation
Homospory vs. heterospory
Homospory produce a single spore type that develops as a bisexual gametophyte, this is seen in most seedless plants.
Heterospory produce 2 types of sporangia that produce 2 types of spores, this is seen in all seed plants
What are the characteristics & function of an ovule?
An ovule consists of the megasporangium (produces megaspore), megaspores (give rise to female gametophyte), and integuments (envelop/protect megasporangium).
How many integuments does a gymnosperm vs. angiosperm ovule have?
gymnosperms have 1, angiosperms have 2
What does a microspore develop into?
A pollen grain, consisting of a male gametophyte enclosed within pollen wall. Tough coat containing sporopollenin
Describe the process of pollination
Pollen is transferred to the vicinity of the ovule. The pollen grain germinates & grows pollen tube into ovule, delivering 2 sperm
Which plants have flagellated sperm?
Bryophytes and seedless vascular plants. Flagella are absent in most gymnosperms and all angiosperms
How are seeds created?
A sperm fertilizes an egg of a seed plant and the zygote grows into a sporophyte embryo. The ovule develops into a seed, consisting of the embryo & its food supply within a protective coat derived from the integument(s)
What makes seeds evolutionary advantageous?
A multicellular seed, compared to a single-celled spore, is more complex & resistant. They contain a food supply.
What is the life cycle of a pine?
1a. Small pollen cones (2n) produce microsporocytes that undergo meiosis to produce haploid microspores (1n). Each microspore develops into a pollen grain containing a male gametophyte.
1b. In larger ovulate cones (2n), megasporocytes undergo meiosis to produce haploid megaspores (1n) inside the ovule. This will develop into a female gametophyte (1n).
2. Pollen is dispersed via air & reaches the female gametophyte. The sperm fertilizes the egg & forms a zygote (2n), which is contained in a seed.
3. The scales of the cone separate & the seeds are dispersed by the wind. The seeds will germinate & emerge as a pine seedling (2n) which develops into a mature sporophyte.
How are seeds stored in gymnosperms vs angiosperms?
Gymnosperm seeds are exposed on sporophylls (modified leaves) that usually form strobili (cones).
Angiosperms seeds & ovules are enclosed in fruits, which are mature ovaries
Archaeopteris, a heterosporous tree with a woody stem that lacks seeds is an example of what?
Progymnosperms, transitional seedless vascular plants
Where were the earliest gymnosperms found & how did it affect their development?
In Carboniferous ecosystems dominated by seedless vascular plants. The climate became warmer/drier during the formation of Pangea, favoring the spread of gymnosperms due to their seeds/pollen
What are the 4 phyla of extant gymnosperms?
Ginkgophyta, cycadophyta, gnetophyta, and coniferophyta
What are the characteristics of ginkgophyta?
Only 1 species. Fanlike leaves that turn gold. The coats of seeds produced by females plants produce a unpleasant odor as they decay
What are the characteristics of cycadophyta?
Large cones & palmlike leaves
What are the characteristics of gnetophyta?
3 genera-
1. Weltwittschia- large straplike leaves
2. Gentum- tropical trees or vines
3. Ephedra- desert shrub
What are the characteristics of coniferophyta?
I.e. pines, firs, spruces, redwoods, etc. Cone of clustered scalelike sporophylls. Most are evergreen. Some are deciduous. Some have needle-shaped leaves adapted for dry conditions.
Which phylum do angiosperms belong to?
anthrophyta
What function does the flower serve for angiosperms?
sexual reproduction
What are the functions of the different parts of a flower?
- Sepals at the base are modified leaves and enclose the flower.
-Petals lie inside the ring of sepals & often are brightly colored to attract pollinators.
-Stamens produce microspores that develop into pollen grains. (The stamen consists of a stalk, the filament, and a terminal sac, the anther, where pollen is produced).
-Carpals produce megaspores + female gametophytes. At the tip is a sticky stigma for pollen reception. A style leads to the ovary at the carpal base.
Which plants have seeds contained within fruits that function as kites/propellers?
Dandelions & maple seeds
What is the life cycle of an angiosperm?
1a. Microsporangia in the anthers develop pollen grains containing male gametophytes. Each male gametophyte has a generative cell (1n) that divides to form 2 sperm and a tube cell (1n) that produces a pollen tube.
1b. The ovule in the ovary contains the embryo sac which contains an egg.
2. Pollen is released from the anther & carried to the stigma at the carpel tip. The pollen grain absorbs water & germinates. The tube cell produces a pollen tube that grows down within the style of the carpel.
3. After reaching the ovary, the pollen tube penetrates the micropyle- a pore in the integuments of the ovule. 2 sperms cells are discharged into the female gametophyte. One fertilizes the egg to form a zygote (2n) while the other fuses with 2 polar nuclei in the central cell of the female gametophyte to form the triploid cell.
4. The ovule matures into a seed. The zygote develops into a sporophyte embryo packed with food. The embryo has a rudimentary root & 1-2 seed leaves (cotyledons). The fertilized nucleus develops into endosperm- food-rich tissue to nourish the embryo.
5. After dispersal by wind or animals, the seed germinates. The seed coat ruptures & emerges a seedling. The seedling initially uses food stored in the endosperm & cotyledons until it can produce it’s own food via photosynthesis.
What is double-fertilization?
One fertilization produces a zygote & another produces a triploid cell, which is unique to angiosperm
In addition to seeds, which of the following characteristics is unique to seed-producing plants?
pollen
In seed plants, which of the following is part of a pollen grain and has a function most like that of the seed coat?
sporopollenin
Which of the following plant structures most directly produces the pollen tube of angiosperms?
male gametophyte
Which part of this figure represents the anther? (diagram of flower)
structure A (tip of male stamen)
The type of life cycle seen in plants is called
alternation of generations
The ____ represents the sporophyte generation of a conifer, and the _____ produces gametophytes
tree … cone
Pollen grains develop in the ____ and are trapped by the ____
anther … stigma
Two characteristics shared by gymnosperms and angiosperms that are absent from earlier plant groups and represent key adaptations to life on dry land are
pollen and seeds
To cross-fertilize flowers A and B, one would first remove flower A’s immature ____ and later transfer pollen from flower B to flower A’s ____
stamens … stigma
The ripened ovary of a flower, which is adapted to disperse seeds, is called a(n)
fruit
Corn, rice, wheat, fleshy fruits such as apples and berries, and many spices are produced by
angiosperms
Which of the following organisms are the closest relatives of pine and spruce trees?
gnetophytes, cycads, and ginkgos
Which of the following statements correctly describes a portion of the pine life cycle?
female gametophytes use mitosis to produce eggs
Within a gymnosperm megasporangium, which of the following develops before the others after fertilization occurs?
megaspore
Which of the following is a characteristic of all angiosperms?
double internal fertilization
What are the three basic organs of a vascular plant?
roots, stems, and leaves
What root system is seen in most eudicots and gymnosperms?
A taproot system, consisting of one large vertical root that develops from an embryonic root
What are the branch roots of taproots?
lateral roots
What root system is seen in most monocots (such as grasses)?
A fibrous root system, a mat of thin roots that spread out below the soil surface
Where does the absorption of water and minerals occur in taproot and fibrous root systems?
Near the root tips containing root hairs
How are lateral shoots developed?
The apical/terminal bud at the apex of a young shoot is removed, the axillary buds break dormancy and give rise to lateral shoots
Nodes vs. internodes
nodes are the points at which leaves are attached, internodes are stem segments between nodes
What is the phenomenon of apical dominance?
Where the presence of a terminal bud is partly responsible for inhibiting the growth of axillary buds
What do modified shoots contain?
stolons, rhizomes, tubers, and bulbs
What is the general structure of a leaf?
a flattened blade and a stalk, the petiole
What is the difference in veins between monocots and eudicots?
most monocots have parallel major veins that run the length of the blade, while eudicot leaves have a branches network of major veins
Simple leaves vs. compound leaves
simple leaves have a single, undivided blade, while compound leaves have several leaflets attached to the petiole
What is the advantage of having a compound leaf?
pathogens that invade the lead are confined to one leaflet
What adaptations might a leaf have that aren’t for the purpose of photosynthesis?
tendrils that cling to supports, spines of cacti for defense, water storage modifications, and bright colors to attract pollinators
What are the functions of the different tissue systems in plants?
Dermal tissue provides a protective outer covering. Vascular tissue transports materials between roots & shoots. Ground tissue contains specialized cells that function in photosynthesis, storage, and support.
How does the dermal tissue system vary between woody and nonwoody plants?
In nonwoody plants, the dermal tissue forms an epidermis that secrets a waxy coating (the cuticle) to retain water
In woody plants, protective tissues called the periderm replace the epidermis in older regions of stems and roots
What are the two types of vascular tissue & their functions?
Xylem, which conducts water & minerals from roots into the shoots
Phloem, which transports sugars from photosynthesis to the roots & sites of growth (i.e. leaves and fruits)
What is the vascular tissue of a root or stem?
The stele
What are the different divisions of ground tissue?
Pith, which internal to vascular tissue, and cortex, which is external to vascular tissue
What are the three basic cell types in plants?
parenchyma, collenchyma, and sclerenchyma
What are the characteristics of parenchyma cells?
primary walls that are thin and flexible, most lack secondary walls, usually protoplasts with large central vacuole, least specialized, perform most metabolic functions
What are the characteristics of collenchyma cells?
thick uneven primary walls, support immature plant shoot parts, grouped into strands or cylinders
What are the characteristics of sclerenchyma cells?
thick secondary walls, strengthened by lignin, rigid, cannot elongate, dead at functional maturity, specialized for support
What are the two types of sclerenchyma cells and their characteristics?
Fibers: long, slender, tapered, occur in groups. (hemp & flax)
Sclereids: irregular shape, short, thick lignified secondary walls (nutshells and seed coats)
What are the water-conducting elements of xylem and what are their characteristics?
Tracheids: long, thin, tapered, function in support and transport, secondary walls hardened with lignin
Vessel elements: wider, shorter, thinner-walled, less tapered, aligned end-to-end
Both are interrupted by pits- thinner regions where only primary walls are present
What are the characteristics of sieve-tube elements?
Chains of cells that move sucrose, organic compounds, and mineral ions in the phloem. Alive at functional maturity, lacks nucleus/ribosomes/distinct vacuole, nonconducting nucleated companion cell connected by numerous plasmodesmata
Indeterminate vs. determinate growth
indeterminate - growing as long as the plant lives
determinate - ceasing to grow after they reach a certain size
Why are plants capable of indeterminate growth?
It has perpetually undifferentiated tissues called meristems
What are the characteristics of apical meristems?
located in tips of roots & axillary buds of shoots, supply cells for growth. The primary growth allows roots to extend thru soil & shoots to increase exposure to light.
What are the characteristics of lateral meristems?
Cylinders of dividing cells that extend along length of roots and shoots. Produce secondary growth, progressive thickening of roots and shoots where primary growth has ceased
What are the functions of vascular cambium and cork cambium?
vascular adds layers of vascular tissue called secondary xylem and phloem. cork replaces the epidermis with thicker, tougher periderm
Annuals vs. biennials vs. perennials
Annuals complete life cycle in 1 year or less
Biennials live for 2 years
Perennials live for many years
What is the function of the root cap?
A covering for the root tip that protects the meristem as the root pushes through the abrasive soil during primary growth. Also secretes polysaccharide slime to lubricate soil & root tip
What are the zones of primary growth?
zone of cell division, including the root apical meristem & derivatives
zone of elongation, where cells elongate
zone of differentiation, where distinct cell types are formed
How does xylem and phloem in eudicot vs. monocot roots?
In eudicot roots, xylem radiates from the center like a star, with phloem developing between
the arms of the xylem “star”
In monocot roots, the vascular tissue consists of a central core of parenchyma surrounded by a
ring of xylem and a ring of phloem
What is the function of ground tissue?
store carbohydrates and absorb water & minerals
What is the endodermis?
a cylinder one cell think that forms a selective barrier between the cortex and the vascular cylinder
Where do leaves develop?
the leaf primordia on the flanks of the apical meristem
Which areas allow damaged leaves to regrow?
intercalary meristems
How are vascular bundles arranged in eudicots vs monocots?
eudicots have vascular bundles arranged in a ring
monocots have vascular bundles scattered throughout the ground tissue
Which cell types are seen in plant stems?
The ground tissue is mostly parenchyma. Collenchyma is just beneath the epidermis. Sclerenchyma fiber cells also provide support.
What are the characteristics of a stomata?
On the epidermal barrier of leaves, allow gas exchange, major avenue of transpiration
What are the characteristics of guard cells?
2 flank each stomata
What are the characteristics of the mesophyll?
the ground tissue of leaves, between upper & lower epidermis, consists mainly of parenchyma cells specialized for photosynthesis
What are the characteristics of veins in leaves?
subdivide and branch throughout the mesophyll, xylem brings water/minerals to photosynthetic tissues, phloem carries organic products to other parts of the plant, each vein enclosed in protective bundle sheath of 1+ layer of parenchyma
Which of the following plant parts absorbs most of the water and minerals taken up from the soil?
root hairs
Which of the following modified roots has a similar function as prop roots?
buttress roots
Which of the following biological molecules is specific to woody sclerenchyma cells?
lignin
Which of the following cell types have unevenly thickened primary walls that support young, growing parts of the plant?
collenchyma cells
Which of the following cell types retains the ability to undergo cell division?
a meristem cell near the root tip
Which of the following cells transport sugars over long distances?
sieve-tube elements
Which of the following cells or tissues arise from lateral meristem activity?
secondary xylem
Which of the following can be used to determine a twig’s age?
number of apical bud scar rings
A plant that grows one year, without flowering, and then grows again the following year and produces flowers before it dies is described as which of the following?
a biennial
Which of the following is the correct sequence of the zones in the primary growth of a root, moving them from the root cap toward the stem?
zone of cell division, zone of elongation, zone of differentiation
Which of the following root tissues gives rise to lateral roots?
pericycle
Additional vascular tissue produced as secondary growth in a root originates from which cells?
vascular cambium
Where does secondary growth occur?
stems & roots of woody plants, rarely in leaves
vascular cambium vs. cork cambium
vascular cambium adds secondary xylem (wood) and secondary phloem, increasing vascular flow and support for the shoot system
cork cambium produces a tough, thick covering consisting of wax-impregnated cells that protect the stem from water loss & foreign invasion
Which plants rarely undergo secondary growth?
monocots
What accounts for most of the increase in diameter of a woody plant?
accumulation of secondary xylem and phloem from the vascular cambium during secondary growth
What is the function(s) of vascular rays?
transfer water + nutrients laterally, store carbohydrates, and aid in wound repair
What does wood consist of?
Tracheids, vessel elements (in angiosperms), and fibers. The thick lignified walls give wood its hardness
What is the difference between wood formed in spring vs. summer?
The tracheid and vessel cells formed in early wood have larger diameters and thinner walls than the later wood. The structure of early wood maximizes deliver of water to leaves while the thick-walled cells of later wood provide more physical support
What is dendrochronology?
the science of analyzing tree ring growth patterns
What is heartwood & what are its characteristics?
Heartwood is older layers of secondary xylem. It no longer transports water or minerals but it contains resins to protect the core of the tree
What is sapwood?
outer layers that transport xylem sap
What are the two tissues produced by cork cambium and what are their characteristics?
Phelloderm: thin layer of parenchyma cells on interior
Suberin: waxy barrier against water loss, physical damage, and pathogens
What is bark?
tissues external to vascular cambium, including the secondary phloem, most recent periderm, and all outer layers of periderm
What is developmental plasticity?
the ability to alter form in response to local environment conditions
What is morphogenesis?
the process that gives a tissue, organ, or organism its shape and determines the positions of cell types
When is the precise plane of cell division in plants usually formed?
late interphase
What does the first sign of spatial orientation look like in plants?
microtubules in the cytoplasm become concentrated into a ring called the preprophase band
What is asymmetrical cell division in plants?
one daughter cell receives more cytoplasm than the other during mitosis. helps establish polarity
What is the development of specific structures in specific locations called?
pattern formation
What are morphological changes that arise from transitions in shoot apical meristem activity called?
phase changes
