How Plants Spread to New Regions
1 Like all living organisms, plants have a driving
need to propagate. The main way flowering plants do this is by having
their seeds spread to new areas. In order for a seed to become a plant, it must
be buried in the soil and then GERMINATE. There are a myriad of ways in which
seeds can spread to different regions, including being transported by gravity,
wind, water, and humans as well as other animals. Seeds sometimes travel
just a meter or are moved thousands of kilometers. They may also disperse into
areas where others of their species are well established, they may colonize new
lands if the growing conditions are sufficient, and they may even assist
ecosystems in recovering from natural disasters.
2 Plants’ seeds come in a variety of forms
and sizes. Many are hidden by the outer husks of nuts or inside the soft flesh of
fruits while others are so miniscule that they are scarcely visible.
Seeds are the end result of plant reproduction. Once they start becoming
plants, the reproduction process of the original plant is complete. Seeds need
to move away from their parent plants to be able to grow into new plants, but
many merely fall to the ground because of gravity when their connections to
their parent plants are terminated.
3 The ground in the immediate vicinity
of a parent plant is not always ideal for seeds since other plants - including
the parent - are typically already utilizing the soil, water, and sunlight that
is available. For instance, the seeds of apple,
orange, and peach trees that get buried beside their parent trees are likely
never to grow into adult trees because they will have to compete with their
parent tree for vital resources. Resultantly, the best way for seeds to become
mature plants is to disperse far from their parent plants.
4 Wind is one most common way that seeds
disperse. Some plants have seeds so tiny and lightweight that they are easily
picked up by the wind and transported great distances. In many cases, evolution
has made seeds more aerodynamic, which lets even light breezes lift and move
them. For example, the dandelion has hair-like growths on its seeds that
give them the appearance of helicopter blades. Other seeds are BUOYANT,so they
may be washed down streams and rivers until they float ashore in new locations.
Some, like coconuts, may float vast distances on the oceans until they reach
remote islands.
5 Seeds wrapped inside fleshy fruits and
nuts are commonly dispersed by animals, which eat the fruits and nuts and
thereby simultaneously ingest the seeds. Later, the animals DEFECATE, so
the seeds, which are not digested inside their bodies, are deposited somewhere
else. Many of these seeds, which have a good source of fertilizer in the animal
feces, germinate and develop into new plants. Other seeds, including walnuts
and acorns are stored by animals such as squirrels and birds. These animals
frequently store the seeds underground, but, at times, they forget about their
caches of nuts, so some germinate and become plants. Humans also play a role in
the scattering of seeds by cultivating fruits and nuts and transporting them
great distances, where some fall into the soil and then grow.
6 Ideally, seeds disperse in areas with
good soil, abundant water resources, and plenty of sunlight. Seeds usually only
germinate when the conditions for their survival are optimal, and many remain
dormant to avoid dangers such as frost, which can kill them. Yet when seeds
germinate, they must compete with plants that are already growing. Crowded
forests, places with poor soil, and regions that receive little rainfall are
not always the best locations for seeds to germinate.
7
Instead, one ideal place for seeds to colonize is an area beginning to recover
from a natural disaster. A place that has recently experienced a forest fire,
for example, is perfect for plant colonization. The organic matter from the
burned dead plants improves the nutrient levels of the soil. Additionally, due
to the lack of other plants - especially tall trees - growing, young plants are
practically guaranteed access to abundant sunlight. This enables them to grow
quickly and to become strong and healthy plants, which is one reason why areas
destroyed by forest fires and floods typically recover so swiftly.
Glossary
germinate: to begin to grow, as in the seed
of a plant
buoyant: able to float on water
15. The word propagate in the
passage is closest in meaning to
(A) evolve (B) mutate (C) reproduce (D) scatter
16. According to paragraph 1, which of the
following is NOT true of seeds?
(A)It is possible for them to move to other
places in a number of ways.
(B) More of them fall close to their
parent plants than move far from them.
(C) They have to be buried in the ground
before they can germinate.
(D) Some of them may start growing in new
places if conditions are ideal.
17. The word miniscule in the passage is
closest in meaning to
(A) exquisite (B) undeveloped (C) tiny
(D) obscure
18. According to paragraph 2, how does
gravity affect seeds?
(A) It causes them to get buried beneath
the surface of the ground.
(B) It makes many of them fall to the
ground beneath their parent plants.
(C) It assists in the germination process
that seeds go through to become plants.
(D) It enables seeds to be hidden inside
the fruits of some plants.
19.
Which of the sentences below best expresses the essential information in the
highlighted sentence in the passage? Incorrect answer choices change the
meaning in important ways or leave out essential information.
(A) The area near a parent plant is not
good for seeds since they must compete against other plants for resources.
(B)
The majority of the seeds that fall near their parent plants fail to get enough
soil, water, and sunlight.
(C)
When a seed falls near its parent plant, it must compete with the parent for
valuable natural resources.
(D) Soil, water, and sunlight are hard for
many seeds to attain when they fall to the ground in some places.
20. According to paragraph 3, which of the
following is true of the seeds of apple, orange, and peach trees?
(A) Very few of these seeds ever germinate
and become mature plants.
(B) It can take them many years before they
germinate and start to grow.
(C) They are among the largest seeds in the
entire plant kingdom.
(D) Those that get buried beside their
parent trees rarely become adult trees.
21. In paragraph 4, the author uses the
dandelion as an example of
(A) a type of plant that can float on
rivers and streams
(B) a plant whose seeds can be moved by
the wind
(C) a flower that has tiny and lightweight
seeds
(D) a kind of plant that is able to
reproduce rapidly
22. The author’s description of coconuts in
paragraph 4 mentions which of the following?
(A)
They have hair-like growths on them that make them easy to move.
(B) They are sometimes the only plants that
grow on remote islands.
(C) Their buoyancy lets them get carried by
rivers, streams, and oceans.
(D) They are able to spread their seeds
by floating on oceans.
23.
The word ingest in the passage is closest in meaning to
(A) chew (B) swallow (C) avoid (D)
digest
24. The word their in the passage
refers to
(A) fleshy fruits (B) the fruits and nuts (C)
the animals (D) the seeds
25. In paragraph 6, the author implies that
seeds
(A) many not grow well in a place that
already has many trees
(B) can remain beneath the ground for
years before germinating
(C)
only germinate in either the spring or summer months
(D) require water every day in order
to become healthy plants
26. According to paragraph 7, seeds can
grow well in places that have recently experienced forest fires because
(A) the regions have no obstructions
that block the sunlight
(B) there are no animals living there that
will eat the seeds
(C) people spread fertilizers in the areas
to make the soil better
(D) water supplies in these regions are
typically ample
27. DIRECTIONS: Select the appropriate
statements from the answer choices and match them to the cause and effect of
seed dispersal to which they relate. TWO of the answer choices will NOT be
used. THIS QUESTION IS WORTH 3 POINTS.
SEED DISPERSAL
CAUSE - - -
EFFECT - -
1. Places that have been flooded may have
new plants grow quickly. ( effect)
2. Animals drop seeds in new places
when they defecate. (cause)
3. Growing plants compete against one
another for sunlight, soil, and water. (effect)
4. Plants start to grow in areas where they
are not common.(X)
5. Seeds do not usually germinate when
weather conditions are poor. (X)
6. Humans transport some fruits and nuts to
faraway places. (cause)
7. The wind lifts light seeds and moves
them to other areas (cause)