Category: Plants

Everything You Need to Know About the Calvin Cycle

The Calvin Cycle occurs during photosynthesis and consists of light independent redox reactions that convert carbon dioxide into glucose. This conversion happens in the chloroplast, or more specifically the stroma of the chloroplast. The chloroplast region is an area between the thylakoid membrane and the inner membrane of the organelle which is typically located in the leaves of plants.

This cycle used to create carbon sugars, mostly, was discovered by Melvin Calvin, Andrew Benson, and James Bassham in 1950 at the University of California. The used radioactive material to trace the pathways carbon atoms took during the carbon fixation step in plant life.

You’ve probably heard the Calvin Cycle called a few other names including the CBB Cycle, C3 Cycle, and dark reactions to name a few.

This process of carbon fixing by plants is essential to all life on the planet. Most new organic growth stems from plants converting carbon to sugars either directly or indirectly. Other plants, or animals, can use these sugars to forms more complex sugars and amino acids when they consume them. It all stems from little plants working day and night to capture light and water.

A Technical Take on the Calvin Cycle

The Calvin Cycle

The Calvin Cycle occurs during photosynthesis and is repeated until it forms a glucose molecule. Photosynthesis goes through two stages to create food and building materials for plants to grow. During the first stage, chemical reactions from light produce ATP and NADPH. The second stage is when the Calvin Cycle takes place. In this stage, carbon dioxide and water get converted to organic materials like glucose. These reactions are called dark reactions which confuses people, but they do not take place at night.

The short explanation of the Calvin Cycle is that it begins with carbon fixation. Carbon dioxide molecules are plucked out of the air to produce glyceraldehyde 3-phosphate. RuBisCO, an enzyme found abundantly around the planet, brings on the carboxylation of a 5-carbon compound and provides a 6-carbon compound that halves itself form two 3-phosphoglycerate. The enzyme phosphoglycerate kinase uses the phosphorylation to create biphosphoglycerate.

Next, the enzyme glyceraldehyde 3-phosphate dehydrogenase uses the reduction of biphosphoglycerate by NADPH. This is called the reduction reactions. Eventually, when the cycle ends, the reactions and reductions produce one glyceraldehyde 3-phosphate molecule per every three carbon dioxide molecules.

That’s a lot of massive words. What that means is the plant uses light and water to convert carbon dioxide into nutrients and oxygen. It takes six turns on the Calvin Cycle for the plant to produce a single glucose molecule. Now that we simplified the process, let’s look at the chemical equation for the Calvin Cycle:

3 CO2 + 6 NADPH + 5 H2O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NADP+ + 9 ADP + 8 Pi (Pi = inorganic phosphate)

The Simplified Function of the Calvin Cycle

Simplified-Calvin-Cycle-diagram

How plants create sugar from sunlight, water, and carbon dioxide is complicated as you probably noted from the previous section. However, plants toil away day and night creating glucose, starch, and cellulose so they can grow. The Calvin Cycle plucks carbon molecules right out of the air and creates new plant growth.

The Calvin Cycle is vital to every ecosystem, and it reaches far beyond the plants using it. Plants are the building blocks of all the food in any ecosystem. Herbivores eat plants for energy and growth while carnivores eat herbivores for the same reasons. In the end, everything goes back into the ground and plants start the process all over again.

If plants stopped all their hard work tomorrow, it would only take a few days for animals to start feeling the effects and starving. Herbivores lose their food right away. Carnivores would follow behind the herbivores. Plants make most of the basic building blocks we all need to continue life as we know it. Without their hard work, we’d all be doomed.

While plants are supplying us with the building blocks, we need to continue living, and they help out the environment in other ways. Because the Calvin Cycle depends on carbon dioxide, plants indirectly play a role in regulating carbon dioxide and other gases proven to be harmful to the atmosphere. Plants perform an essential role in helping us clean the air we breathe.

The Calvin Cycle Step by Step

Calvin Cycle step by step

Carbon fixation is the first step. We explained it in brutal technical detail above, but let’s look at it in simpler terms in this section. A carbon dioxide molecule is plucked from the air and combined with a five-carbon acceptor molecule called ribulose-1,5-bisphosphate, or RuBP for short. The result is a six-carbon molecule.

The six-carbon molecule is split in half to form a set of new carbon molecules called 3-phosphoglyceric acid, or 3-PGA for short. The new three-carbon molecules are catalyzed by an enzyme called RuBisCo. This creates the simple sugar molecules the Calvin Cycle needs for stage two. On a side note, because it is used by every plant during photosynthesis, the RuBisCo enzyme if the most common catalyst on Earth. The result of this step is passed on to the next phase.

Step two of the Calvin Cycle is called the reduction step. The 3-PGA molecules created in the carbon fixation step are used in phase two to develop glyceraldehyde-3 phosphate or G3P for short. G3P is a simple sugar. This process uses energy and reactions captured during light-dependent stages of photosynthesis.

This step is called the reduction step because electrons are stolen from molecules created during photosynthesis and given to our new sugars. In chemistry, when you take electrons from a molecule, it’s called a reduction hence the name of this stage. Technically, the electrons are donated and not taken. Taking electrons by force is called oxidation, and that’s not what happens in this stage.

At this point, our plant has created sugar it can store for a long time and use for energy. Anything that eats this plant gets to take advantage of these sugars as well including humans. The plant may choose to use these stored molecules to form new plant materials or repair itself, but that’s not part of the Calvin Cycle so we won’t get into it. This is the end of the sugar-producing phase of the Calvin Cycle.

The final stage of the Calvin Cycle is called the regeneration step. Some of the G3P are held back and not used to make sugars. Instead, they are used to revitalize the five – carbon compound the Calvin Cycle needs to start the process over again. It takes six carbon molecules to make glucose, so plants have to go through the Calvin Cycle six times to make one glucose molecule.

Once the plant has completed this cycle six times, the Calvin Cycle ends and begins again. So, technically, the Calvin Cycle is all three steps done six times each. Plants repeat this process over and over during daylight hours. At night they continue to work making various compounds that don’t require light. This makes plants the most efficient lifeforms on the planet.

Bonus Information About Plants and Their Internal Food Factories

plants

We usually consider waste products bad or at least not edible. However, we need the waste materials plants to produce to survive. An essential waste, or by-product, plants produce is oxygen. While plants are using water and carbon dioxide to make sugars, they release oxygen into the air around them as a waste product.

The delicious fruits and vegetables we all enjoy get most of their flavor from the carbon sugars plants store for energy. From the crunchy stalk of the celery plant to the succulent meat of the peach, plants developed all using just carbon dioxide, water, sunlight, and a few minerals leeched from the soil. I think we can assume these tasty treats are little gifts from the plant kingdom.

The tiny organelles called chloroplasts on the surface of a plant’s leaves can move. Ok, they can’t move individually, but in many plants, they can turn the leaf, so it gets better exposure to sunlight. These plant-based solar cells help capture sunlight so being able to point yourself in the sun makes sense. Some plants take it to another level and bend their stalk or branches to help reach the sunlight.

Some Final Notes

photosynthesis diagram

The fantastic plants we ignore all around us are vital to our survival. They use energy from the Sun in little energy reactors called chloroplasts to do all sorts of cool things. If you glance at the bigger picture and oversimplify it, plants take light from the Sun and turn it into carbon sugars they can store for long periods of time. We could call them solar powered batteries if we want to be humorous about the process.

Plants pitch in and help everywhere they can from cleaning the air to enriching the soil they grow in for the next plants. Plants give us so many things from apples to steak. Without plants toiling away at the bottom of the food chain, nothing in the top of the food chain could survive. Every food we consume comes from plants either directly or indirectly.

Seed Plants

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Seed Plants

 

 

True/False
Indicate whether the sentence or statement is true or false.
1.
Tracheids and sieve tubes make up a xylem vessel.
2.
The main function of ground tissue is to conduct water and minerals.
3.
Vascular tissue is found within ground tissue, which makes up the outside of the plant.
4.
The outer protective layer of tissue on a vascular plant is known as the meristem.
5.
Monocot stems cannot become large in diameter because they lack lateral meristems.
6.
The loss of water by transpiration at the leaves helps pull water into the plant at the roots.
7.
The blade of a compound leaf is divided into leaflets.
8.
Many gymnosperms, such as pine, spruce, and fir trees, produce their seeds in cones.
9.
The flowers of angiosperms are ornamental and have no reproductive function.
10.
Brightly colored petals, scents, and nectar are all adaptations of flowers that help ensure pollination.
11.
Plants with colorful flowers are pollinated most commonly by wind.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
12.
The conducting cells of phloem are called
a.
tracheids.
c.
sieve plates.
b.
sieve tube members.
d.
vessel elements.
13.
Plants grow in regions of active cell division called
a.
meristems.
c.
phloem.
b.
xylem.
d.
dermal tissue.
14.
The lengthening of plant roots and shoots is called
a.
secondary growth.
c.
primary growth.
b.
germination.
d.
vascular growth.
seed_plants_files/i0170000.jpg
15.
Refer to the illustration above. The structure indicated at “f”
a.
supports the anther.
b.
produces pollen.
c.
has tiny structures that look like leaves.
d.
develops into a fruit.
16.
Refer to the illustration above. The structure labeled “c”
a.
produces pollen.
c.
is sticky to the touch.
b.
contains sperm cells.
d.
contains meristematic tissue.
17.
The process of transferring pollen from a male cone to a female cone in gymnosperms is called
a.
fertilization.
c.
pollination.
b.
seed formation.
d.
asexual reproduction.
18.
If a plant’s flowers are very colorful and produce nectar, the plant is probably pollinated by
a.
water.
c.
insects.
b.
wind.
d.
self-pollination.
19.
Fertilization
a.
involves the union of the egg and sperm.
b.
may not follow pollination at all.
c.
may not occur until weeks or months after pollination has taken place.
d.
All of the above
20.
After an egg has been fertilized, a fruit develops from the
a.
style.
c.
ovule.
b.
ovary.
d.
sepal.

 

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Moss & Fern Quiz

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Moss and Fern

 

 

True/False
Indicate whether the sentence or statement is true or false.
1.
Land plants have a complex life cycle that involves an alternation of generations between a haploid gametophyte and a diploid sporophyte.
2.
The sporophyte of a nonvascular plant is larger and lives longer than the gametophyte.
3.
The life cycle of nonvascular plants involves alternation of generations.
4.
Mosses, liverworts, and hornworts all are generally found in moist habitats.
5.
Nonvascular plants have true leaves but lack true stems and roots.
6.
Mosses and ferns no longer require the presence of a film of water for reproduction.
7.
Ferns need water to reproduce because their sperm must swim to eggs.
8.
Mosses are called pioneer plants because they can promote the development of new communities in barren areas that have been burned or destroyed by humans.
9.
Sphagnum moss is used in potting and gardening soils because of its ability to encourage water drainage.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
10.
The ancestors of today’s land plants were probably
a.
brown algae.
c.
green algae.
b.
red algae.
d.
lichens.
11.
The challenges faced by early land plants included
a.
conserving water.
b.
reproducing on land.
c.
absorbing minerals from the rocky surface.
d.
All of the above
12.
The diploid form in a plant’s life cycle is called the
a.
sporophyte.
c.
parental generation.
b.
gametophyte.
d.
alternate generation.
13.
The haploid form in a plant’s life cycle is called the
a.
sporophyte.
c.
parental generation.
b.
gametophyte.
d.
alternate generation.
14.
Which of the following is not a bryophyte?
a.
moss
c.
hornwort
b.
liverwort
d.
fern
15.
Which of the following is not characteristic of all nonvascular plants?
a.
They produce seeds.
b.
They have an alternation of generations lifestyle.
c.
They produce spores.
d.
They require water for sexual reproduction.
16.
The water-retaining ability of sphagnum moss makes it ideal for
a.
using in garden-soil mixes.
b.
use in packing bulbs and flowers for shipping.
c.
use in houseplant soils.
d.
All of the above
17.
Similarities shared by monocots and primitive dicots suggest that
a.
monocots and dicots evolved independently.
b.
monocots were on Earth long before dicots.
c.
monocots evolved from dicots.
d.
dicots evolved from monocots.

 

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Introduction to Plants Study Guide

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Introduction to Plants Quiz

 

 

Modified True/False
Indicate whether the statement is true or false.  If false, change the identified word or phrase to make the statement true.
 1.
Plants are multicellular prokaryotes. _________________________


 2.
The plant life cycle includes a diploid gamete and a haploid spore. _________________________


 3.
Mosses are most often found in dry environments. _________________________


 4.
Mosses and liverworts lack a vascular system for transporting water and nutrients. _________________________


 5.
Water must be present for fertilization to take place in mosses. _________________________


 6.
In mosses and liverworts, eggs are formed through mitosis in the antheridia. _________________________


 7.
Gametophytes of conifers are physically much larger than their sporophytes. _________________________


 8.
One important difference between mosses and ferns is that mosses have a vascular system. _________________________


 9.
Shoots, stems, and roots characterize the bodies of vascular plant sporophytes. _________________________


 10.
Ferns are characterized by fronds and fiddleheads. _________________________


 11.
Haploid fern spores are produced by gametophytes. _________________________


 12.
In ferns, a large sporophyte with leaves called fronds alternates with a heart-shaped gametophyte. _________________________


 13.
Ferns need water to reproduce because their sperm must swim to eggs. _________________________


 14.
Both mosses and ferns require a thin film of water for gametes to meet. _________________________


 15.
In both mosses and ferns, eggs are formed through mitosis in the antheridia. _________________________


 16.
Gymnosperm seeds are enclosed in a fruit. _________________________


 17.
Gametophytes of seed plants are large and easily viewed with the unaided eye. _________________________


 18.
Sexual reproduction in seed plants involves the transfer of pollen from the male reproductive structures of a plant to the female reproductive structures. _________________________


 19.
Seed plants cannot reproduce without a film of water for transferring of gametes. _________________________


 20.
A seed is a structure that contains a plant embryo. _________________________


 21.
A plant embryo is a new sporophyte. _________________________


 22.
In flowering plants, the embryos of monocots have two cotyledons. _________________________


 23.
Pollen is produced in the tip of the stamen, a structure called the sepal. _________________________


 24.
The lower portion of the pistil produces pollen. _________________________


 25.
Gametophytes develop within flowers. _________________________


 26.
Pollen tubes grow through the style toward the ovule. _________________________


 27.
Many seeds have appendages that aid in dispersal. _________________________


 28.
Asexual reproduction produces new plants that are genetically different from the parent plant. _________________________


 29.
Vegetative reproduction does require a plant to have flowers. _________________________


 30.
In vegetative reproduction, new plants may be generated from stems or roots. _________________________


 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 31.
The ancestors of today’s land plants were probably
a.
brown algae.
c.
green algae.
b.
red algae.
d.
lichens.
 32.
Among the challenges that faced early land plants were
a.
eliminating excess water.
b.
obtaining sunlight for photosynthesis.
c.
absorbing minerals from the rocky surface.
d.
avoiding being eaten by grazing mammals.
 33.
The waxy protective covering of a land plant is called a
a.
cuticle.
c.
rhizome.
b.
capsule.
d.
stoma.
 34.
Some land plants developed an internal system of interconnected tubes and vessels called
a.
cuticles.
c.
a circulatory system.
b.
nonvascular canals.
d.
vascular tissue.
 35.
sporophytes : spores ::
a.
sporophytes : gametophytes
c.
gametes : gametophytes
b.
gametophytes : gametes
d.
sporophytes : gametes
 36.
The diploid form in a plant’s life cycle is called the
a.
sporophyte.
c.
parental generation.
b.
gametophyte.
d.
alternate generation.
 37.
The haploid form in a plant’s life cycle is called the
a.
sporophyte.
c.
parental generation.
b.
gametophyte.
d.
alternate generation.
 38.
A haploid stage following a diploid stage in a plant’s life cycle is called
a.
generational recycling.
c.
alternating forms.
b.
periodic gametogenesis.
d.
alternation of generations.
 39.
In plants, haploid gametes are produced as a result of
a.
fertilization.
c.
encapsulation.
b.
meiosis.
d.
mitosis.
 40.
sporophytes : meiosis ::
a.
sporophytes : spores
c.
gametophytes : gametes
b.
gametophytes : mitosis
d.
sporophytes : gametes
 41.
Mosses, hornworts, and liverworts all possess
a.
fibrous roots.
c.
tap roots.
b.
spore capsules.
d.
green leaves.
 42.
In nonvascular plants, structures in which spores are produced are known as
a.
meristems.
c.
cones.
b.
pollen grains.
d.
sporangia.
 43.
Which of the following statements about moss spores is not true?
a.
They are produced by the sporophyte.
b.
They are dispersed and then germinate.
c.
They are produced in a capsule-like top.
d.
They are diploid.
 44.
The sporophyte generation in mosses produces spores by
a.
meiosis.
c.
sexual reproduction.
b.
mitosis.
d.
asexual reproduction.
 45.
The most noticeable form of a moss life cycle is the
a.
sporophyte.
c.
rhizoid.
b.
gametophyte.
d.
zygote.
 46.
In which of the following structures do seedless plants produce eggs?
a.
antheridia
c.
archegonia
b.
capsules
d.
cones
 47.
antheridia : sperm ::
a.
rhizoids : gametes
c.
archegonia : eggs
b.
seeds : gametophytes
d.
sperm : megaspores
 48.
Both mosses and ferns produce
a.
seeds.
c.
flowers.
b.
fruit.
d.
spores.
 49.
Fern sporophytes consist of rhizomes,
a.
large leaves, and flowers.
c.
pollen grains, and ovules.
b.
cones, and stems.
d.
roots, and fronds.
 50.
Unlike mosses, ferns possess
a.
spore capsules.
c.
antheridia.
b.
archegonia.
d.
vascular tissue.
 51.
Fiddleheads are produced by
a.
whisk ferns.
c.
ferns.
b.
club mosses.
d.
horsetails.
 52.
Both mosses and ferns produce gametes through
a.
mitosis.
c.
osmosis.
b.
meiosis.
d.
diffusion.
 53.
vascular plants : sporophytes ::
a.
sporophytic plants : gametophytes
c.
spores : gametes
b.
gametes : sporophytes
d.
nonvascular plants : gametophytes
The diagram below shows the plant life cycle.

nar001-1.jpg

 54.
Refer to the diagram above. At which point in the life cycle does fertilization take place?
a.
1
c.
3
b.
2
d.
4
 55.
Refer to the diagram above. The structures produced at 3 are called
a.
sporangia.
c.
spores.
b.
archegonia.
d.
antheridia.
 56.
Which of the following were the first land plants to evolve seeds?
a.
angiosperms
c.
mosses
b.
gymnosperms
d.
horsetails
 57.
liverworts, hornworts, and mosses : nonvascular plants ::
a.
gymnosperms and angiosperms : bryophytes
b.
ferns : mosses
c.
gymnosperms and angiosperms : seed plants
d.
bryophytes and liverworts : vascular plants
 58.
gymnosperms : naked seeds ::
a.
pollen : mosses
c.
liverwort : vascular tissue
b.
liverwort : pollen
d.
angiosperms : enclosed seeds
 59.
In seed plants, female gametophytes produce
a.
sperm.
c.
cells.
b.
eggs.
d.
spores.
 60.
A male gametophyte of a seed plant develops into a
a.
pollen grain.
c.
pollen tube.
b.
spore capsule.
d.
seed coat.
 61.
The partially developed plant found in seeds is known as a(n)
a.
gametophyte.
c.
embryo.
b.
spore capsule.
d.
sporophyte.
 62.
A typical seed contains all of the following except a(n)
a.
seed coat.
c.
embryo.
b.
nutritious tissue.
d.
spore case.
 63.
The tallest trees in the world are a species of
a.
conifers.
c.
liverworts.
b.
dicots.
d.
angiosperms.
 64.
The process of transferring pollen from a male cone to a female cone in gymnosperms is called
a.
fertilization.
c.
pollination.
b.
seed formation.
d.
asexual reproduction.
 65.
In conifers, the diploid condition is resumed following
a.
pollination.
c.
respiration.
b.
fertilization.
d.
sporulation.
 66.
The seeds of monocots have
a.
one embryo and two cotyledons.
c.
one embryo and one cotyledon.
b.
two embryos and two cotyledons.
d.
two embryos and one cotyledon.
 67.
Flowering plants are classified as monocots or dicots according to the number of their
a.
leaves.
c.
meristems.
b.
flowers.
d.
cotyledons.
 68.
Monocots and dicots are subdivisions of
a.
angiosperms.
c.
ferns.
b.
gymnosperms.
d.
mosses.
nar002-1.jpg
 69.
Refer to the diagram above. The structure labeled f
a.
supports the anther.
c.
supports the pistil.
b.
produces pollen.
d.
develops into a fruit.
 70.
Refer to the diagram above. The structure labeled c
a.
produces pollen.
b.
contains sperm cells.
c.
is the area where pollen lands and sticks.
d.
contains meristematic tissue.
 71.
Removing a flower’s stigma would initially affect
a.
fertilization.
c.
pollination.
b.
seed production.
d.
seed dispersal.
 72.
Pollen is produced in a structure called the
a.
anther.
c.
ovary.
b.
stigma.
d.
pistil.
 73.
In angiosperms, immediately following pollination,
a.
the seed develops.
c.
fertilization occurs.
b.
an egg cell is formed.
d.
the pollen tube begins to form.
 74.
During fertilization in flowering plants, one sperm fuses with an egg to form an embryo, and another fuses with two nuclei to form nutritive tissue. This event is called
a.
self-pollination.
c.
maximization.
b.
adaptation.
d.
double fertilization.
 75.
fruit : mature ovary
a.
gametophyte : sporophyte
c.
cotyledon : food reserve
b.
gymnosperm : angiosperm
d.
vascular plant : nonvascular plant
 76.
If a plant’s flowers are very colorful and produce nectar, the plant is probably pollinated by
a.
water.
c.
insects.
b.
wind.
d.
self-pollination.
 77.
One way that flowers produced by angiosperms help ensure the transfer of gametes is by
a.
traveling in the air currents.
b.
bursting open and projecting gametes onto the landscape.
c.
attracting animals that carry pollen from one flower to another.
d.
producing tasty fruits that animals depend on for food.
 78.
What function do all fruits produced by angiosperms perform?
a.
produce nutrients for the plant
b.
nourish the embryos
c.
disperse the seeds
d.
ensure pollination
 79.
Which structure allows plants to reproduce asexually?
a.
tuber
c.
archegonium
b.
flower
d.
antheridium
 80.
The production of offspring genetically identical to the parent plant is the result of
a.
sexual reproduction.
c.
alternation of generations.
b.
asexual reproduction.
d.
double fertilization.
 

Completion
Complete each statement.
 81.
The surface of a vascular plant is covered by a waxy, waterproof layer called a(n) ____________________.

 82.
One of the first environmental challenges that early land plants had to overcome was developing a way to conserve ____________________.

 83.
The sporophyte generation produces spores by the process of ____________________.

 84.
The haploid form of a plant is known as the ____________________ generation.

 85.
Nonvascular plants transport materials within their bodies through the process of ____________________.

 86.
A green, hornlike sporophyte growing upward from the gametophyte is typical of plants known as ____________________.

 87.
In mosses and liverworts, the ____________________ generation is the dominant generation.

 88.
The very tiny liverwort ____________________ grow from the archegonia under the caps of female stalks.

 89.
The gametophytes of ____________________ plants are larger and more noticeable than the sporophytes.

 90.
The seedless plants produce sperm within the ____________________.

 91.
True roots, stems, and leaves are associated with ____________________ plants.

 92.
A fern is an example of a(n) ____________________ vascular plant.

 93.
Both mosses and ferns produce eggs within structures called ____________________.

 94.
Like the nonvascular plants, the seedless vascular plants can reproduce sexually only when a film of ____________________ covers the gametophyte.

 95.
Unlike mosses, ferns have sporophytes that are much ____________________ than their gametophytes.

 96.
Seed plants whose seeds do not develop within a sealed container (fruit) are called ____________________.

 97.
Fruit is a characteristic associated only with the flowering plants, or ____________________.

 98.
A male gametophyte of a seed plant develops into a(n) ____________________.

 99.
The ____________________ is the protective cover that surrounds a seed.

 100.
The seed coat prevents the embryo from drying out, from mechanical injury, and from ____________________.

 101.
A(n) ____________________ is a specialized structure that develops from an ovule and serves to protect a plant embryo from harsh conditions.

 102.
The four major groups of gymnosperms are gnetophytes, cycads, ginkgoes, and ____________________.

 103.
A mature pine tree produces both male and female ____________________.

 104.
Gymnosperms are pollinated by ____________________, which makes sexual reproduction possible even during dry conditions.

 105.
The life cycle of a conifer is characterized by a large ____________________ generation.

 106.
In conifers, seeds form on the ____________________ of cones.

 107.
A plant that has flower parts that occur in fours or fives or multiples of four or five is a member of a subgroup called a(n) ____________________.

nar002-1.jpg
 108.
Refer to the diagram above. The structure labeled f is called the ____________________.

 109.
Refer to the diagram above. The structure labeled b is called the ____________________.

 110.
Refer to the diagram above. A flower like this one has all four basic flower parts and thus is an example of a(n) ____________________ flower.

 111.
The transfer of pollen grains from an anther to a stigma is known as ____________________.

 112.
In angiosperms, seeds develop from the ____________________ inside a(n) ____________________ after an egg has been fertilized.

 113.
The event in which one sperm fertilizes an egg and a second sperm fuses with two nuclei is called _________________________.

 114.
A flower is a(n) ____________________ structure that produces pollen and seeds.

 115.
Flowers are a source of ____________________ for pollinators.

 116.
The seeds of angiosperms are enclosed in ____________________.

 117.
Because flowering plants are rooted in the ground and cannot move from place to place, they must disperse their ____________________ so that their offspring can grow in new environments.

 118.
Many fruits are spread by ____________________ that are attracted to sweet, fleshy fruits, which they use for food.

 119.
Many of the structures by which plants reproduce vegetatively are modified ____________________.

 120.
Bulbs, stolons, and tubers are examples of modified stems that allow plants to reproduce ____________________.

 

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