Chapter 25- Plant Responses + adaptations
true or false? Plant growth follows patterns that are the same for all species
False
what is a target cell?
The portion of an organism affected by a particular hormone
what is a hormone?
a substance that is produced in one part of an organism and affects another part of the same individual
What are gibberellins?
another group of plant hormones and are important in initiating seed germination
the closer a bud is to the stem's tip the more it is inhibited. What is this phenomenon called.
apical dominance
the venus fly trap is an example of what kind of nutritional specialist
carnivorous
the folding together of mimosa leaflets when touched is the result of what changes in cells at the base of each leaflet
change of osmotic pressure
what are herbicides
compounds that are toxic to the plant
what are xerophytes
desert plants
what do fruit tissues do in response to auxins
initiate early growth or release hormone ethylene, which stimulates plant to ripen
how does the venus fly trap obtain the nutrient it needs from and insect?
it receives nitrogen directly from the insect from the protein inside of the bug
why do cacti have small leaves or no leaves at all?
it reduces the rate of transpiration and allows the plant to store the most water
how does nicotine protect a tobacco plant from potential predators
its a natural insecticide that disrupts the nervous system of bugs
what is a lateral bud
meristemic area on the side of a tem that gives rise to side branches
what common plant grows as a parasite on conifers in the western US?
mistletoe
why do the roots of xerophytes have many hairs
so they can quickly absorb rainfall before water sinks too deep into soil
what adaptations do the leaves of salt-tolerant plants have that protects them against high salt concentrations?
specialized cells that pump salt out of the tissues and onto leaf structures
what are three plant adaptations to a desert climate?
1. Extensive roots 2. Reduced leaves 3. thick stems that can store water
When light hits one side of stem, a higher concentration of auxins develops on the ______ side. the concentration of auxins stimulates cells on the shaded side to_________ as a result, the stemp bend towards the ____________
1. shade 2. elongate 3. light
what is true about hormones and plant growth? A. Plant hormones are produced in growing flowers and fruits B. Single hormones may affect two different tissues in different ways c. hormones can activate the transcription of certain genes d. All plant cells are affected by all plant hormones
A, B, C
Phototropism
A growth response to light
what is dormancy?
A period when an organism's growth or activity stops
which are true about plant growth? A. chemicals direct, control, and regulate plant growth. B. Meristems are found at places where plants grow rapidly C. Plants stop growing when they reach maturity D. Even very old plants continue to grow
A, B, D
which are true about auxins A. Auxins cause roots to grow downward B. Auxins regulate cell division in meristem C. Snipping off the tip of a plant removes the source of auxins D. in roots, auxins stimulate cell elongation
A. Auxins... B.Auxins... C.Snipping...
what are two examples of how cytokinins produce effects opposite to those of auxins
A. Cytokinins inhibit the growth of lateral and cause cells to grow thicker B.stimulate lateral bud growth
which is true about the effects of thigmotropism A.the tendrils of a grapevine wrap tightly around any object they encounter B. a plant that is touched regularly may be stunted in growth C. the stems of climbing plants don't grow straight up d. when the tip of a vine encounters an object, it breaks off
A. the... B.A... C.The
what are two ways in which plant hormones control plant growth?
A. they control; patterns of development b. they control plant responses to the environment
which are true about cytokinins A. they delay the aging of leaves B. the stop cell division and growth of lateral buds C. They often produce effects opposite of those of auxins
A. they... C.they... D. They...
what is true about the adaptations of aquatic plants? A. all aquatic plants grow very slowly after germination B. in waterlilies, oxygen diffuses from open spaces in petioles to roots C.the knees of mangrove trees bring oxygen rich air down to roots D. the seeds of some aquatic plants can float in water
B, C, D
what nutrient do carnivorous plants need to obtain from insects that they can't other get?
nitrogen
how do waterlilies get oxygen to their roots?
oxygen diffuses from open spaces in petioles to the roots
What plant pigment is responsible for photoperiodism?
phytochrome
how does phytochrome control photoperiodism?
phytochrome absorbs red light and activates a number of signaling pathways within plant cells
what are cytokinins
plant hormones that are produced in growing roots and in developing fruits and seeds
What are long-day plants?
plants that flower when the days are long
what are epiphytes?
plants that grow directly on the body's of other plants
how do shorter days and lower temps. affect photosynthesis?
reduce efficiency because, auxin production drops, ethylene increases, less chlorophyll being produced. an abscission layers seals the leaf off and leaf falls off
Gravitropism
response of plant growth to the force of gravity
what is photoperiodism?
response to changing lengths of day and night
Thigmotropism
response to touch
ethylene is a plant hormone that caused fruit to ___
ripen
what does a trigger in venus' flytrap that causes the leaf to snap shut?
sensory cells
particularly in stems and fruits, gibberellins produce dramatic increases in _____
size
when days shorten at summer's end, what changes start a series of events that gradually shut down the leaves of flowering plants?
the change in the amount of auxin and ethylene
what adaptations do aquatic plants have that allow them to grow in mud that is saturated with water and nearly devoid of oxygen?
the contain air filled spaces in their tissues
abscission layer
the layer of cells at the petiole that seals off a leaf from the vascular system
what do tropisms demonstrate about plants
the plants ability to respond to the conditions the live in
what is gravitropism
the response of a plant to the pull of gravity
what are tropisms
the response of plants to environmental stimuli
What is photoropism?
the tendency of a plant to grow towards light
what is photoperiodism responsible for?
the timing of seasonal activitie such as flowering and growth
from their experiment with oak seedlings, what did the Darwin suspect about the seedlings
the top of each seedling produced substances that regulate cell growth
where are auxins produced and how are they distributed in a plant
they are produced in the apical meristem and are transported downward to the rest of the plant
what is the advantage for many desert plants that have seeds that can remain dormant for years?
they can survive long droughts because they germinate when sufficient moisture guarantees them a chance for survival
why are plants such as chrysanthemums and poinsettias called short day plants?
they flower when days are short
why aren't epiphytes considered to be plant parasites?
they gather their own moisture and produce their own food
how do many plants defend themselves against insect attack?
they produce antimicrobial chemicals.
how do auxins affect plant cells
they stimulate cell elongation
as cold weather approaches, what happens to deciduous plants?
they turn off photosynthetic pathways, transports materials from leaves to roots, an seals off seed
where is most of a desert plant's photosynthesis carried out?
thick green stems
why doesn't a tree's sap freeze during a cold winter?
xylem and phloem tissues pump themselves full of ions and organic compounds.