14.1 Plant Organs, Tissues, and Cells Flashcards
roots, shoots, leaves, and flowers are __________
plant organs
Flowering plants reproduce sexually, producing ____
seeds
true or false; plants can reproduce asexually
true
The three main tissue systems of plants are…
dermal, vascular, and ground
tissue systems
organ systems ____ between the two groups of angiosperms
differ
two groups of angiosperms:
monocots and dicots
Dicotyledons, or dicots
larger group, containing broad-leaf
species
examples of dicotyledons
dandelions, canola, and maple trees
monocotyledons or monocots
contain species with long, thin leaves
examples of monocotyledons
grasses, orchids, and lilies.
Roots
structures that anchor a plant in the soil,
absorbing minerals and water and providing structural support
Monocots have ______ root systems
fibrous
what is a fibrous root system
A fibrous root system consists of a mat of thin roots spread out below the soil surface, providing increased exposure to
soil nutrients and water
most dicots have a _______ system
taproot
what is a taproot system
characterized by one large vertical root with many smaller branches
examples of dicots with taproots
Carrots, turnips, and beets are examples of dicots with very large, starch-storing taproots
Shoots
usually above-ground structures consisting of stems, leaves, and flowers
stems
parts of a plant that support leaves and
flowers
nodes
Nodes are the points on the stem at which leaves are attached
internodes
portions of the stem between nodes
importance of stems
Stems play an important role in transporting materials in a plant
function of vascular tissue
transports water and minerals from the roots up to the leaves, and food from the leaves to other parts of the plant, such as
growing buds, flowers, and roots.
true or false: the stems of cacti are a type of shoot
true
The stems of cacti are specialized to
store water
Tubers, such as potatoes, are swollen shoots that
store starch
The thorns that protect a hawthorn bush are actually …
modified branches
An onion is an underground shoot, modified for
food storage
Undeveloped shoots are called
buds
A terminal bud is found at the
tip of a stem
Axillary buds are found in the
angles formed by a leaf and the main stem
what are the angles formed by a leaf called?
axils
Growth from axillary buds forms the
plant’s branches
Leaves
primary food-manufacturing sites of a plant
Most plant leaves are flattened and
thin, allowing them to…
intercept and capture sunlight
effectively
The main part of the leaf is the
blade
A stalk, called a _________, connects the leaf to the stem
petiole
The vein that runs through the petiole and into the blade carry ___________ into the leaf and transport ________ from the leaf to other parts of the plant
water and nutrients; sugars
The _________, or arrangement of
veins, differs in the leaves of monocots and dicots
venation
In a monocot leaf, several major veins run _______ along the length of the leaf blade
parallel
A dicot leaf has a ___________ of veins
branching network
true or false: spines on a cactus are leaves
true
Because an onion bulb is a modified shoot, the layers of an onion are actually
leaves
give an example of petioles in the food you eat
Celery has enormous petioles (the “stalks” that you eat)
flower
A flower is a specialized shoot, unique to angiosperms, that usually consists of four different rings of modified leaves
what are the four different rings of modified leaves
sepals, petals, stamens, and pistils
sepals
The outermost ring that covers and protects the flower bud before the blossom opens
example of a sepal
rosebud
Why do some flower petals have “runway” markings?
helps guide insect pollinators toward the flower’s reproductive parts
stamens
In the centre of the flower are the stamens, the male reproductive structures
pistils
the female reproductive structures
true or false: all species have stamens and pistils together on the same flower
false
Some species, however, have stamens and pistils on separate flowers or even separate plants
Each stamen consists of a long stalk topped by a sac called an ________.
anther
Within the anthers, meiosis produces ______ that develop into __________
spores; pollen
grains
Each pollen grain is a ____________, consisting of two cells surrounded by a thick protective wall
male gametophyte
At the base of each female pistil is an
ovary
Inside the ovary are
structures called
ovules
Ovules contain the
female gametophyte
When fertilized, ovules develop into
seeds
Leading to the ovary is a narrow
structure called the ____, which has a sticky tip called the ______ (plural,
stigmata)
style; stigma
describe sexual reproduction in a plant
During pollination, pollen grains released from anthers land on the stigmata of flowers
Once on a stigma, a pollen grain absorbs water and extends a structure called a pollen tube.
The pollen tube, which contains two sperm nuclei, grows toward the ovary through the style.
When the pollen tube reaches the ovule in the ovary, a sperm cell fertilizes the egg cell in the ovule and forms a zygote, which develops into the plant embryo.
The other sperm cell contributes to the development of a nutrient-rich tissue, called endosperm, that nourishes the growing embryo.
Several pollen tubes may grow down
a style at once, competing with one another to fertilize one ovule
Monocot flowers tend to have sepals, petals, and reproductive parts
in
multiples of three
Dicot flowers tend to have parts in
multiples of four or five
true or false: dicot flowers can have six parts
true
(there are exceptions to the general rule for dicots)
seed coat
Seeds have a tough outer layer called a seed coat that helps to protect the tiny embryo and endosperm inside
In many seeds, the endosperm is the
food source for the developing embryo and may contain
starch, proteins,
and oils
An embryonic leaf, called the ________, also develops
cotyledon
cotyledon
functions in the storage and transfer of nutrients to the embryo and is especially important in seeds without endosperm
how many cotyledons do monocots have
1
(mono)cotyledon=1
how many cotyledons do dicots have
2
(di)cotyledon=2
After several cycles of mitosis, why is the growth and development of the plant
embryo within the seed temporarily suspended?
because this is the stage when the seed is usually dispersed from the parent plant
true or false: Green peppers, walnuts,
cucumbers, maple tree keys, coconuts, and corn are all types of fruits
true
ways seed dispersal can occur
Some seeds travel by sticking onto a passing animal’s fur, as burrs.
Some seeds, such as coconuts, travel on water (again, encased in the fruit).
Others are so tiny and lightweight that
they can be carried by the wind
Some seeds, such as the touch-me-not, are ballistically propelled several metres from the plant
When conditions are favourable, the plant embryo within a seed begins to grow. This process is called
germination
what happens to seeds when they get water?
Most seeds must soak up water in order to germinate.
By taking up water, the seed expands and splits its seed coat.
The water also triggers metabolic changes in the embryo that enable it to grow
give an example of how dicots have an adaptation that protect the developing shoot as it grows toward the surface
some dicots have a hooked shoot tip
-this protects the delicate shoot tip by holding it downward as the shoot moves through the soil
-as the shoot breaks through the soil surface, its tip is lifted gently out of the
soil and straightens out
give an example of how monocots have an adaptation that protect the developing shoot as it grows toward the surface
In most monocots, a sheath surrounding the shoot pushes straight upward, breaking through the soil
-the delicate shoot then grows upward through this protective tunnel.
-after emerging into the light, the first leaves expand from the shoot and begin making food by photosynthesis
-at this stage, the young plant is called a
seedling
Asexual reproduction in plants is called
vegetative reproduction
how do some plants reproduce asexually
Some plants, such as cacti, drop stems or other shoots that establish new roots and become clones.
Other plants, such as strawberry plants and many grasses, send out runners.
Some trees and shrubs send out shoots from the base of their trunks or from underground stems.
-these clones may persist long after the original plant dies
how do humans help plants reproduce asexually
The simplest way to clone a plant is to cut off a leaf or stem and place the cut end in water or soil.
In many plants, the cells at the cut end of the petiole or stem become undifferentiated and then form new plant tissues and organs.
The result is the formation of a new plant, genetically identical to the original one.
The first plants to be cloned in this way were
carrots
grafting
widely used by fruit growers, allowing them to combine a high-quality fruit-bearing stem with a tough and hardy root or to put
several varieties of a fruit on one plant
Plants have three main tissue systems:
dermal, vascular, and ground tissue
systems
dermal tissue
The dermal tissue is the outer covering or “skin” of the plant
epidermis
The epidermis, the dermal tissue of non-woody organs, such as young roots, consists of one or more layers of cells
true or false: The epidermis covers and protects all the old parts of the plant
false
-protects young parts
give an example of how epidermis are specialized
epidermis of leaves and stems secretes a
waxy cuticle, an adaptation that helps plants retain water.
many plant species have epidermal hairs that trap or poison insects, protecting the plant from insect herbivores.
Located in the epidermis of leaves and some other tissues are pores called
stomata (singular, stoma)
what occurs in the stoma
Gas and water exchange between the environment and the interior of the plant occurs through stoma
vascular tissue
-transports water, mineral nutrients, and
organic molecules between roots and shoots
-also contributes to the structural support of the plant
2 types of vascular tissue
xylem and phloem
xylem
transports water and dissolved minerals upward from roots into shoots.
phloem
transports food made in mature leaves to the roots and the parts of the shoot
system that don’t carry out photosynthesis, such as developing leaves, flowers, and fruits.
vascular tissue in monocots
A monocot stem has vascular bundles scattered throughout its tissue
vascular tissue in dicots
The vascular bundles of a dicot stem are arranged in a ring
ground tissue
-fills the spaces between the dermal and vascular tissues is ground tissue
-makes up most of a young, non-woody plant and functions in photosynthesis in the shoot and in storage and support throughout the plant.
The ground tissue of the root consists primarily of a mass of cells called the
cortex
The plant tissues are made up of three basic cell types:
parenchyma, collenchyma, and sclerenchyma
parenchyma
-most abundant type of cell
-has thin cell walls and, typically, large central vacuoles
-perform a variety of functions in the plant, including food storage, photosynthesis, and cellular respiration
-fruits are made up mostly of parenchyma cells.
-food-conducting cells of phloem are also parenchyma cells
collenchyma
-have unevenly thickened cell walls.
-grouped in strands or cylinders
-provide support in parts of plant that are still growing
-young stems and petioles often have
collenchyma just below their surface
sclerenchyma
-specialized for support
-cells grow and then die within mature part of a plant
-their lignin-rich cell walls are left behind, creating a “skeleton” that supports the plant.
-For example, the water-conducting cells of xylem are specialized sclerenchyma cells
The upper and lower surfaces of the leaf are covered by tightly packed __________. These cells are covered by a _________, reducing the amount of water that is lost by the leaf.
epidermal cells; waxy cuticle
function of waxy cuticle on leaf
reduces the amount of water that is lost by the leaf
guard cells
regulate the opening and closing of the
stomata, controlling the diffusion of gases into the leaf and the loss of water vapour from the leaf.
The ground tissue of the leaf is made of _______, a type of parenchyma cell that is specialized for ____________
mesophyll; gas exchange
Dicots have ___ layers of mesophyll cells
2
Under the upper epidermis is a layer of elongated palisade mesophyll cells that are specialized for …
capturing light energy
and carrying out photosynthesis
Next to the lower epidermis is a layer
of loosely packed _________ cells
spongy mesophyll
spongy mesophyll is also known as
aerenchyma
Air spaces within the spongy mesophyll allow
carbon dioxide and oxygen to
circulate within the leaf
leaf mesophyll in monocots
One type of mesophyll
leaf mesophyll in dicots
Palisade and
spongy mesophyll
developing shoot in monocots
Protected by sheath
developing shoot in dicots
Hooked
vascular bundles in stems of monocots
Scattered
vascular bundles in stems of dicots
Arranged in a ring
secondary growth in monocots
Absent
secondary growth in dicots
often present
Give an example of
(a) a modified leaf
-spines on a cactus
-tendrils on a pea plant or a grapevine are modified leaves (allow a plant to attach to and climb along a surface)
Give an example of
(b) a modified shoot
onion bulb is a modified shoot
Name the four rings of modified leaves
that make up a flower.
sepals, petals, stamens, and pistils
State the function of sepals
covers and protects the flower bud before the blossom opens
state the function of petals
have “runway” markings that help guide insect pollinators toward the flower’s reproductive parts
state the function of stamens
male reproductive structures
state the function of pistils
female reproductive structures
Name the male and female gametophytes of an angiosperm
male gametophyte- pollen grains
female gametophyte- seeds
List four ways that seeds can be dispersed, and give an example of each
Some seeds travel by sticking onto a passing animal’s fur, as burrs
-e.g. birds eat the fruit of plants (wild grape) which disperses seeds in their droppings after digestion
Some seeds, travel on water
-e.g. coconuts
Others are so tiny and lightweight that
they can be carried by the wind.
-e.g. a dandelion
Some seeds are ballistically propelled several metres from the plant
-e.g. touch-me-not plant
Explain why each of the following statements is incomplete or incorrect.
(a) Within the ovaries of a flower, meiosis
produces spores that develop into pollen
grains
this happens in the anthers not ovaries
Explain why each of the following statements is incomplete or incorrect.
(b) Putting a seed in a warm, moist
environment will cause it to germinate
Most seeds must soak up water in order to germinate. By taking up water, the seed expands and splits its seed coat.
Also depends on the plant because some have more specific requirements
-e.g. some seeds require exposure to the intense heat of a brush fire before
germinating.
Explain the role of endosperm and cotyledon(s) in nourishing a young plant embryo.
Endosperm:
nutrient-rich tissue that nourishes the growing embryo
Cotyledons:
the cotyledon functions in the storage + transfer of nutrients to the embryo and is especially important in seeds without endosperm
Young seedlings are adapted to grow through soil without damage to the young shoot. Describe one such adaptation in
(a) monocots
In most monocots, a sheath surrounding the shoot pushes straight upward, breaking through the soil.
The delicate shoot then grows upward through this protective tunnel
Young seedlings are adapted to grow through soil without damage to the young shoot. Describe one such adaptation in
(b) dicots
some dicots have a hooked shoot tip
-this protects the delicate shoot tip by holding it downward as the shoot moves through the soil
-as the shoot breaks through the soil surface, its tip is lifted gently out of the
soil and straightens out
dermal tissue
outer covering or “skin” of the plant.
vascular tissue
transports water, mineral nutrients, and
organic molecules between roots and shoots
also contributes to the structural support of the plant.
ground tissue
functions in photosynthesis in the shoot and in storage and support throughout the plant
Describe how plant cloning and grafting are used in agriculture and horticulture.
Vegetative reproduction/ Cloning
-gives us a way to breed useful crops
or decorative plants, without needing to wait for seeds produced by the
desired plant to develop
-also ensures that plants will be genetically
identical with the desired traits
Grafting
-widely used by fruit growers, allowing them to combine a high-quality fruit-bearing stem with a tough and hardy root or to put several varieties of a fruit on one plant
apical meristem form and function
causes primary growth (lengthening plant)
occurs at tips of shoots and roots
produces new leaves and flowers
lateral meristems form and function
causes secondary growth (widening of plant)
occurs at cambium
produces bark on trees
