plant Flashcards
1
Q
A
2
Q
The production of new plants from underground stems is an example of __________ reproduction.
A
Asexual
Asexual reproduction involves a single parent and does not require gametes.
3
Q
Sexual reproduction in plants, as in all organisms, requires__________.
A
A male and female gamete
This process involves pollination and fertilization.
4
Q
Spores are produced during the __________ stage of a plant’s life cycle.
A
Sporophyte
The sporophyte is the diploid phase that produces spores.
5
Q
What special types of cell are produced during the gametophyte stage of a plant’s life cycle?
A
Sex cells
These cells are also known as gametes.
6
Q
One difference between sexual reproduction in plants and animals is that in plants, sex cells __________.
A
Are produced in structures made of haploid cells
This contrasts with animal sex cells produced in diploid gonads.
7
Q
The male part of the flower that contains the pollen producing parts is the:
A
Stamen
The stamen consists of the anther and filament.
8
Q
The innermost part of the flower that contains the ovaries that make the ovules is the:
A
Carpels
Carpels are essential for fertilization processes.
9
Q
The base of the flower where it is attached to the rest of the plant, is the:
A
Receptacle
The receptacle supports the flower and connects it to the stem.
10
Q
The colorful parts of the flower within the sepals together called the corolla are:
A
Petals
Petals attract pollinators through their color.
11
Q
The parts of the flower that are the leaflike outermost layer altogether called the calyx are the:
A
Sepals
Sepals protect the developing flower bud.
12
Q
A flower that lacks one or more organs is called a(n) __________.
A
Incomplete flower
Incomplete flowers may lack male or female reproductive structures.
13
Q
If a stigma receives pollen from another flower of the same species, the flower is __________.
A
Cross-pollinated
Cross-pollination promotes genetic diversity.
14
Q
When a butterfly drinks from a flower, the pollen attaches to the __________.
A
Stigma
The stigma receives pollen during pollination.
15
Q
Moths feed on flowers that are open at night. These flowers are usually __________.
A
Pale in color and sweetly scented
This attracts moths, which rely on scent.
16
Q
During pollination, pollen grains are transferred from the anther to the __________.
A
Pistil
The pistil is the female reproductive organ of the flower.
17
Q
Pollen is produced by the __________.
A
Anther
The anther is part of the male reproductive system.
18
Q
Nectar-feeding pollinators are attracted to a flower by its color or _____?
A
Scent
Scent signals the presence of nectar.
19
Q
The base of the pistil is the __________.
A
Ovary
The ovary houses the ovules that develop into seeds.
20
Q
The flowering plant group which is the biggest in the plant kingdom is:
A
Angiosperms
Angiosperms have flowers, fruits, and enclosed seeds.
21
Q
Angiosperms differ from mosses, ferns and fungi in that they have:
A
Seeds and flowers
This distinguishes them from non-flowering plants.
22
Q
What is the name of the process by which a plant makes its own food?
A
Photosynthesis
Photosynthesis converts sunlight into chemical energy.
23
Q
These are a type of plant that reproduce by seeds not contained in a flower:
A
Gymnosperms
Gymnosperms have exposed seeds on cones.
24
Q
Cone-bearing plants are called _______________.
A
Conifers
Conifers include trees like pines and spruces.
25
The leaves of conifers are in the form of _____________.
Needles
## Footnote
Needle-like leaves help conifers adapt to their environments.
26
What type of leaves do conifers have?
Needles
## Footnote
Conifers are a type of tree that have needle-like leaves instead of broad, flat leaves.
27
How are conifers adapted to their environments?
Conifers are well adapted to cold and dry environments
## Footnote
This adaptation helps them conserve water and withstand harsh weather conditions.
28
What role do conifers play in ecosystems?
They provide habitat, food, and shelter for many organisms
## Footnote
Conifers are important for maintaining biodiversity in various ecosystems.
29
Fill in the blank: The leaves of conifers are in the form of _____________.
Needles
30
True or False: Conifers have broad, flat leaves.
False
## Footnote
Conifers have needle-like leaves, which is a key characteristic that distinguishes them from deciduous trees.
31
What is one advantage of the needle shape of conifer leaves?
It helps conserve water and reduces surface area for evaporation
## Footnote
This adaptation is crucial for survival in dry environments.
32
In what types of regions are conifers commonly found?
Various regions around the world
## Footnote
Conifers can thrive in a range of climates, particularly in colder areas.
33
What is metabolism?
Metabolism describes all the chemical reactions that occur within living organisms to maintain life.
34
What is metabolic waste?
Metabolic waste is the products of metabolic reactions that are unnecessary or harmful to the organism and must, therefore, be eliminated through excretion.
35
Define excretion.
Excretion is the removal of the waste products of metabolism from the body of an organism.
36
Do plants have a specialized organ system for excretion?
No, plants do not have a specialized organ system for excretion.
37
What is the primary product of photosynthesis?
Glucose.
38
What are the gaseous waste products of photosynthesis and respiration?
Photosynthesis liberates oxygen; respiration produces carbon dioxide and water vapor.
39
What is aerobic respiration?
Aerobic respiration is the process by which energy is released in the cells in the presence of oxygen.
40
During photosynthesis, what is the equation?
Carbon dioxide + water + light energy = glucose + oxygen + water.
41
During respiration, what is the equation?
Glucose + oxygen = carbon dioxide + water + energy.
42
What is stomata?
Stomata (singular: stoma) are pores in the epidermis of leaves through which gas exchange takes place with the atmosphere.
43
What are lenticels?
Lenticels are openings on the surfaces of stems and roots through which gas exchange takes place with the atmosphere.
44
What is transpiration?
Transpiration is the loss of water through evaporation from the aerial parts of a plant to the atmosphere.
45
What percentage of water lost from a plant is due to stomatal transpiration?
About 90%.
46
What is guttation?
Guttation is the process of excreting xylem sap through the hydathodes at the margins of leaves.
47
What are hydathodes?
Hydathodes are pores in the epidermis of leaf margins through which xylem sap is excreted during guttation.
48
What is the primary substance excreted from the plant via guttation?
Xylem sap.
49
What can nitrogenous waste in plants be converted into?
Nitrogenous waste can be converted into reusable forms to synthesize proteins.
50
What is cuticle?
The cuticle is a waxy layer that coats the epidermis of the aerial parts of a plant.
51
Fill in the blank: Waste products can be stored in the ______ of a plant, which can then drop off when no longer required.
leaves
52
What is the percentage of water lost through lenticular transpiration?
About 0.1%.
53
What is the role of root pressure in guttation?
Root pressure creates an upward pressure that causes water to be excreted through hydathodes.
54
How do plants eliminate excess gaseous waste products?
By releasing them into the atmosphere via gas exchange.
55
What is the main function of stomata?
To allow gas exchange and transpiration.
56
What type of plants often accumulate calcium oxalate crystals?
Plants growing in soils containing excess calcium.
57
What is the significance of transpiration for plants?
Transpiration helps regulate temperature and facilitates nutrient uptake.
58
What is the primary function of leaves in plants regarding waste products?
Leaves store waste products that drop off from the plant when no longer required.
59
What must plants do with metabolic waste products?
They must either excrete or reuse them.
60
What are the gaseous waste products generated by photosynthesis and respiration used for?
They are used as substrates for the opposite reaction.
61
How do plants eliminate excess gaseous waste?
Through gas exchange with the atmosphere.
62
What are the three types of transpiration through which water can be eliminated?
* Stomatal
* Lenticular
* Cuticular
63
What is guttation?
The exudation of water through pores called hydathodes.
64
What happens to nitrogenous waste products generated through protein metabolism?
They are reused in protein synthesis.
65
What are raphides?
Insoluble crystals in some plants that store mineral salts like calcium oxalate.
66
What is respiration in plants?
A chain of chemical reactions that synthesizes energy required to sustain life.
67
Do plants breathe?
Yes, plants breathe and require oxygen to respire.
68
What structures do plants use for gas exchange?
* Stomata (in leaves)
* Lenticels (in stems)
69
What is the difference between breathing and respiration?
Breathing is a step involved in respiration; plants respire all through their life.
70
What is the process by which plants generate glucose molecules?
Photosynthesis.
71
When does respiration become evident in plants?
At nighttime.
72
What is the role of stomata in leaves?
Regulate gas exchange by opening and closing.
73
What do roots absorb for respiration?
Air from the spaces between soil particles.
74
What is the primary function of chlorophyll in plants?
To enable photosynthesis.
75
What is the main difference between respiration and photosynthesis?
Respiration occurs in all living things; photosynthesis occurs only in green plants.
76
What are the two main types of respiration?
* Aerobic Respiration
* Anaerobic Respiration
77
Where does aerobic respiration take place?
In the mitochondria of eukaryotic entities.
78
What does anaerobic respiration produce?
Ethyl alcohol and carbon dioxide.
79
Do plants breathe at night?
Yes, plants breathe throughout their life span both day and night.
80
What is the chemical equation for cellular respiration?
Oxygen + Glucose -> Carbon Dioxide + Water + Heat Energy.
81
What is the role of lenticels in woody stems?
Facilitate respiration or exchange of gases.
82
What part of roots is involved in the exchange of respiratory gases?
Root hairs.
83
Stomatal transpiration
Stomatal transpiration is the evaporation of water molecules from the stomata. As we have learned, stomata are capable of opening or closing depending on the need for gas exchange. During the daytime, when the light intensity is high, plant cells carry out photosynthesis. The stomata therefore open to allow the diffusion of carbon dioxide from the atmosphere into the leaves. At the same time, since the stomata are open, transpiration takes place. In most plants, the leaves contain a type of tissue made up of mesophyll cells. This type of tissue can be spongy and, therefore, has large intercellular spaces. Water vapor usually accumulates in these intercellular spaces before being eliminated via transpiration through the stomata. Overall, stomatal transpiration accounts for about 90% of the water lost from a plant through transpiration.
84
Lenticular transpiration
Lenticular transpiration is the evaporation of water molecules from the lenticels on the stems of woody plants. Only a minimal volume of water, around 0.1% of the total water lost through transpiration, is lost in this way.
85
Cuticular transpiration
Cuticular transpiration is the evaporation of water molecules through the cuticle. The cuticle is a waxy layer that coats the epidermis of the aerial parts of a plant. Cuticular transpiration can happen when the stomata are closed. Overall, cuticular transpiration accounts for less than 10% of the total water lost through transpiration. The rate of cuticular transpiration depends on the thickness of the waxy cuticle. Plants growing under extremely hot and dry conditions can develop thick cuticles to prevent excess water loss through transpiration.
86
transpiration day and night
Lenticular and cuticular transpiration occur throughout the day and night. However, at night, when the stomata are generally closed, since photosynthesis cannot take place, transpiration is accomplished primarily through the lenticels and cuticle.
87
percentage of water lost during transpiration
stomatal 90%
lenticel about 0.1%
cuticular less than 10%
87
Aside from transpiration, water can also be eliminated from the bodies of some plants in the liquid form, through a process called ____________
Aside from transpiration, water can also be eliminated from the bodies of some plants in the liquid form, through a process called guttation. The water droplets exuded through guttation are rich in dissolved minerals. These water droplets should not be confused with dewdrops, which are formed by the condensation of water molecules from the atmosphere on the surfaces of plants.
88
Excess xylem sap is exuded in the form of water droplets through structures called the _____________s,
Excess xylem sap is exuded in the form of water droplets through structures called the hydathodes, found in the margin of the leaves
89
guttation
Guttation is the process of excreting xylem sap through the hydathodes at the margins of leaves. While transpiration generally occurs during the daytime, guttation is more likely to happen at night or in the early morning, when the stomata are closed and the plant needs to eliminate large amounts of water.
90
lants growing in soils containing excess calcium tend to accumulate insoluble crystals of calcium oxalate, called_________, in their roots, leaves, or tubers.
raphides
91
resins and gums
Some plants can store certain waste products in resins or gums, which accumulate in old xylem vessels. Some plants may also produce these substances in response to injuries. Secretions like latex and oils can contain metabolic waste, and they accumulate in the bark, leaves, or stems. The photo below shows an example of resin secreted from the trunk of a tree.
92
Complete the statement to describe one form of waste removal in plants: Waste products can be stored in the of a plant, which can then drop off when no longer required.
A.stem
B.spores
C.ovules
D.leaves
Answer
Plants survive by performing metabolic reactions, in which a set of reactants are converted into products that the plant needs for its growth and survival. Aside from the products that the plant needs, certain other compounds are also generated through metabolic reactions, which are beyond the plant’s requirements. These are called metabolic wastes and must be eliminated from the plant’s body.
Sometimes plants can generate waste products in the form of mineral salts or acids, which could have a toxic effect on the plant if allowed to accumulate. These compounds are converted into insoluble crystals and stored in the cytoplasm or vacuole of some plant cells. Since these crystals cannot dissolve, this prevents these potentially toxic compounds from spreading to different parts of the plant and causing harmful effects. These insoluble crystals accumulate in the leaves, bark, or fruits, which are eventually shed, leaving the plant free from toxic substances. For example, plants growing in soils containing excess calcium tend to accumulate insoluble crystals of calcium oxalate, called raphides, in their roots, leaves, or tubers.
Let’s take a look at the options provided in the question. Of the listed options, leaves are the only organs in which waste products can be stored, which then drop off from the plant when no longer required.
Therefore, waste products can be stored in the leaves of the plant, which then drop off when no longer required.
93
key points in plant excretion
Plants generate metabolic waste products that must be either excreted or reused.
The gaseous waste products generated by photosynthesis and respiration are used as substrates for the opposite reaction.
Gas exchange occurs with the atmosphere to eliminate excess gaseous waste.
Water can be eliminated through evaporation via three different types of transpiration: stomatal, lenticular, and cuticular.
Water can be eliminated as a liquid, in the form of xylem sap, through guttation, in which it is exuded through pores called the hydathodes.
The nitrogenous waste products generated through protein metabolism are reused in protein synthesis.
Waste products consisting of mineral salts, such as calcium oxalate, are stored as insoluble crystals called raphides in some plants.
94
95
What are the 'three Fs' that characterize angiosperm reproduction?
Flowers, double fertilization, and fruits.
96
What is alternation of generations in plants?
A life cycle alternating between multicellular haploid gametophyte and multicellular diploid sporophyte.
97
What is the function of sepals and petals?
Sepals protect the flower bud; petals attract pollinators.
98
What are the male and female reproductive organs in flowers?
Stamens (male) and carpels (female).
99
What structures make up a stamen?
Anther and filament.
100
What is a carpel and what are its parts?
Female reproductive organ: stigma, style, and ovary.
101
What is a pistil?
A single carpel or group of fused carpels.
102
What are complete and incomplete flowers?
Complete: have all 4 floral organs; Incomplete: lack one or more floral organs.
103
How is a male gametophyte formed?
Microspores undergo mitosis to form pollen grains with generative and tube cells.
104
How is a female gametophyte (embryo sac) formed?
A megaspore undergoes mitosis to form 8 nuclei, which are organized into the embryo sac.
105
What is pollination?
Transfer of pollen from anther to stigma.
106
What is double fertilization?
One sperm fertilizes the egg (zygote), the other fuses with two polar nuclei to form endosperm (3n).
107
What does the ovule and ovary develop into?
Ovule becomes seed; ovary becomes fruit.
108
What is the structure of a eudicot seed?
Includes two cotyledons, hypocotyl, radicle, and epicotyl.
109
What is the structure of a monocot seed?
One cotyledon (scutellum), coleoptile (shoot sheath), coleorhiza (root sheath).
110
What is seed dormancy?
A state where the seed does not germinate until conditions are favorable.
111
What triggers seed germination?
Imbibition (water uptake); radicle emerges first.
112
How are fruits classified?
Simple (single ovary), aggregate (multiple ovaries of one flower), multiple (inflorescence), accessory (includes other flower parts).
113
What is apomixis?
Asexual seed production from diploid cells without fertilization.
114
What are advantages of asexual reproduction in plants?
Preserves successful genotypes, useful in stable environments.
115
How do plants prevent self-fertilization?
Mechanisms like self-incompatibility, dioecy, and structural separation.
116
What is vegetative propagation?
Asexual reproduction from cuttings, grafts, or tissue culture.
117
What is plant biotechnology?
Use of plants for useful products; includes genetic modification.
118
What are biofuels and their source?
Renewable fuels made from plant biomass like switchgrass and cellulose.
119
What is Golden Rice?
A transgenic crop enriched with vitamin A to reduce deficiency.
120
What is a concern about GM crops?
Possible escape of transgenes to wild species and effect on non-target organisms.
121
flowers of deceit
Insects help angiosperms to reproduce sexually
with distant members of their own species
– For example, male Campsoscolia wasps mistake
Ophrys flowers for females and attempt to mate
with them
– The flower is pollinated in the process
– Unusually, the flower does not produce nectar
and the male receives no benefit
122
T/F Angiosperms can reproduce sexually and
asexually
True
123
Flowers, double fertilization,
and fruits are unique features of the
angiosperm life cycle
Plant lifecycles are characterized by the alternation
between a multicellular haploid (n) generation and
a multicellular diploid (2n) generation
* Diploid sporophytes (2n) produce spores (n) by
meiosis; these grow into haploid gametophytes (n)
* Gametophytes produce haploid gametes (n) by
mitosis; fertilization of gametes produces a
sporophyte
124
dominant generation in angiosperm
In angiosperms, the sporophyte is the dominant
generation, the large plant that we see
* The gametophytes are reduced in size and
depend on the sporophyte for nutrients
* The angiosperm life cycle is characterized by
“three Fs”: flowers, double fertilization, and fruits
125
Flower Structure and Function
Flowers are the reproductive shoots of the
angiosperm sporophyte; they attach to a part of
the stem called the receptacle
* Flowers consist of four floral organs: sepals,
petals, stamens, and carpels
* Stamens and carpels are reproductive organs;
sepals and petals are sterile
126
Flower Structure and Function
A stamen consists of a filament topped by an
anther with pollen sacs that produce pollen
* A carpel has a long style with a stigma on which
pollen may land
* At the base of the style is an ovary containing one
or more ovules
* A single carpel or group of fused carpels is called
a pistil
127
A single carpel or group of fused carpels is called
a
pistil
128
complete and incomplete flowers
Complete flowers contain all four floral organs
* Incomplete flowers lack one or more floral
organs, for example stamens or carpels
129
Clusters of flowers are called
inflorescences
130
Development of Male Gametophytes in
Pollen Grains
* Pollen develops from microspores within
the microsporangia, or pollen sacs, of anthers
* Each microspore undergoes mitosis to produce
two cells: the generative cell and the tube cell
* A pollen grain consists of the two-celled male
gametophyte and the spore wall
If pollination succeeds, a pollen grain produces a
pollen tube that grows down into the ovary and
discharges two sperm cells near the embryo sac
131
Development of Female Gametophytes
(Embryo Sacs)
* The embryo sac, or female gametophyte,
develops within the ovule
* Within an ovule, two integuments surround a
megasporangium
* One cell in the megasporangium undergoes
meiosis, producing four megaspores, only one of
which survives
* The megaspore divides, producing a large cell
with eight nuclei
* This cell is partitioned into a multicellular female
gametophyte, the embryo sac
132
pollination
* In angiosperms, pollination is the transfer of
pollen from an anther to a stigma
* Pollination can be by wind, water, or animals
* Wind-pollinated species (e.g., grasses and many
trees) release large amounts of pollen
133
abiotic pollination by wind
hazel staminate flower
hazel cappellate flower
134
pollination by bees
common dandelion
135
pollination by moth and butterflies
yucca flower
136
pollination by flies
blowfly on carrion flower
137
pollination by bats
long nosed bat on cactus flower
138
Coevolution of Flower and Pollinator
* Coevolution is the evolution of interacting species
in response to changes in each other
* Many flowering plants have coevolved with
specific pollinators
* The shapes and sizes of flowers often correspond
to the pollen transporting parts of their animal
pollinators
– For example, Darwin correctly predicted a moth
with a 28 cm long tongue based on the
morphology of a particular flower
139
Double Fertilization
* After landing on a receptive stigma, a pollen grain
produces a pollen tube that extends between the
cells of the style toward the ovary
* Double fertilization results from the discharge of
two sperm from the pollen tube into the embryo
sac
* One sperm fertilizes the egg, and the other
combines with the polar nuclei, giving rise to the
triploid food-storing Plant Fertilization endosperm
(3n)
140
double fertilization
141
Seed Development, Form, and Function
* After double fertilization, each ovule develops into
a seed
* The ovary develops into a fruit enclosing the
seed(s)
142
Endosperm Development
* Endosperm development usually precedes
embryo development
* In most monocots and some eudicots, endosperm
stores nutrients that can be used by the seedling
* In other eudicots, the food reserves of the
endosperm are exported to the cotyledons
143
Embryo Development
* The first mitotic division of the zygote splits the
fertilized egg into a basal cell and a terminal cell
* The basal cell produces a multicellular suspensor,
which anchors the embryo to the parent plant
* The terminal cell gives rise to most of the embryo
* The cotyledons form and the embryo elongates
144
Structure of the Mature Seed
* The embryo and its food supply are enclosed by a
hard, protective seed coat
* The seed enters a state of dormancy
* A mature seed is only about 5–15% water
145
Structure of the Mature Seed
* In some eudicots, such as the common garden
bean, the embryo consists of the embryonic axis
attached to two thick cotyledons (seed leaves)
* Below the cotyledons the embryonic axis is called
the hypocotyl and terminates in the radicle
(embryonic root); above the cotyledons it is called
the epicotyl
* The plumule comprises the epicotyl, young leaves,
and shoot apical meristem
146
Grasses, such as maize and wheat, have a
special cotyledon called a
scutellum
147
Two sheathes enclose the embryo of a grass
seed: a ____________ covering the young shoot and
a ___________ covering the young root
Two sheathes enclose the embryo of a grass
seed: a coleoptile covering the young shoot and
a coleorhiza covering the young root
148
Seed Dormancy: An Adaptation for Tough
Times
* Seed dormancy increases the chances that
germination will occur at a time and place most
advantageous to the seedling
* The breaking of seed dormancy often requires
environmental cues, such as temperature or
lighting changes
* In many eudicots, a hook forms in the hypocotyl,
and growth pushes the hook above ground
* Light causes the hook to straighten and pull the
cotyledons and shoot tip up
* In maize and other grasses, which are monocots,
the coleoptile pushes up through the soil
149
Fruit Form and Function
* A fruit develops from the ovary
* It protects the enclosed seeds and aids in seed
dispersal by wind or animals
* A fruit may be classified as dry, if the ovary dries
out at maturity, or fleshy, if the ovary becomes
thick, soft, and sweet at maturity
150
Fruits are also classified by their development
– Simple, a single or several fused carpels
– Aggregate, a single flower with multiple separate
carpels
– Multiple, a group of flowers called an
inflorescence
An accessory fruit contains other floral parts in
addition to ovaries
151
fruit dispersal mechanisms include
– Water- cocunut
– Wind. dandelion seeds (one seeded fruits , winged seed of tropical asian climbing gourd, alsomitra macrocarpa, winged fruit of maple
– Animals- puncture vine, tribulus terrestrial,
152
Flowering plants reproduce
sexually, asexually, or both
* Many angiosperm species reproduce both
asexually and sexually
* Sexual reproduction results in offspring that are
genetically different from their parents
* Asexual reproduction results in a clone of
genetically identical organisms
153
_______________ is the asexual production of seeds from
a diploid cell
Apomixis is the asexual production of seeds from
a diploid cell
154
Mechanisms of Asexual Reproduction
* Fragmentation, separation of a parent plant into
parts that develop into whole plants, is a very
common type of asexual reproduction
* In some species, a parent plant’s root system
gives rise to adventitious shoots that become
separate shoot systems
155
Mechanisms That Prevent Self-Fertilization
* Many angiosperms have mechanisms that make it
difficult or impossible for a flower to self-fertilize
* Dioecious species have staminate and carpellate
flowers on separate plants
* The most common is self-incompatibility, a
plant’s ability to reject its own pollen
* Researchers are unraveling the molecular
mechanisms involved in self-incompatibility
* Some plants reject pollen that has an S-gene
matching an allele in the stigma cells
* Recognition of self pollen triggers a signal
transduction pathway leading to a block in growth
of a pollen tube
156
Advantages and Disadvantages of Asexual
Versus Sexual Reproduction
* Asexual reproduction is also called vegetative
reproduction
* Asexual reproduction can be beneficial to a
successful plant in a stable environment
* However, a clone of plants is vulnerable to local
extinction if there is an environmental change
157
A _______is a mass of dividing undifferentiated
cells that forms where a stem is cut and produces
adventitious roots
callus
158
Grafting
* A twig or bud can be grafted onto a plant of a
closely related species or variety
* The stock provides the root system
* The scion is grafted onto the stock
159
________plants are genetically modified (GM)
to express a gene from another organism
Transgenic plants are genetically modified (GM)
to express a gene from another organism
160
Protoplast fusion
is used to create hybrid plants
by fusing protoplasts, plant cells with their cell
walls removed
161
example of product of artificial selection
maize
162
The grain triticale is derived from a successful
cross between
wheat and rye
163
Transgenic crops have been developed that
– Produce proteins to defend them against insect
pests
– Tolerate herbicides
– Resist specific diseases
* Nutritional quality of plants is being improved
– For example, “Golden Rice” is a transgenic variety
being developed to address vitamin A deficiencies
among the world’s poor
164
Some GMOs have health benefits
– For example, maize that produces the Bt toxin has
90% less of a cancer-causing toxin than non-Bt
corn
– Bt maize has less insect damage and lower
infection by Fusarium fungus that produces the
cancer-causing toxi
165
Efforts are underway to prevent trans gene escape by
introducing
– Male sterility
– Apomixis
– Transgenes into chloroplast DNA (not
transferred by pollen)
– Strict self-pollination
