Download Plant Behaviors and Evolution Plant Behaviors and Evolution

Plant Behaviors and Evolution
By Cindy Grigg
When you look at a plant, you may not see much happening. But, like people and animals, plants have needs.
Living things can live on Earth because Earth has certain things that allow them to grow and reproduce. Plants need
light, air, water, and space.
1
Plants also need nutrients, or certain substances found in soil, to live. Some nutrients come from rocks which are filled
with minerals. Minerals are not living, but they contain compounds that plants use as nutrients. These nutrients become
part of the soil when rock minerals break up into very small pieces and dissolve. A plant takes in nutrients through its roots
along with water.
2
Plants also get nutrients from other living things. When plants and animals die, they decay and release their nutrients
which then return to the soil. This is why putting dead leaves or grass clippings on your garden is good for it.
3
Plants that live in different habitats have different traits that allow them to survive there. Over time, adaptations, or
changes, in plant parts have happened. They continue to happen to increase the chances that plant species can survive
in their habitat. Adaptations are what make the sizes and shapes of plant parts different.
4
Plants can't move like animals can, but they can respond to a stimulus, or a change in the environment. Plant growth
in response to a stimulus is called a tropism. Plants respond to stimuli such as light, gravity, water, and touch.
5
When you plant a seed in the soil, you don't have to worry about which direction the seed faces. Why? Because plant
roots respond to gravity. They will always grow down toward the center of the earth. Stems always grow upward, away
from the pull of gravity. Plant growth in response to gravity is called gravitropism (grav-ih-TROH-piz-um) or geotropism.
6
If you place a plant near a window, you will notice that, eventually, most of the leaves will be facing the sun. The
leaves turn when cells on one side of the stem grow longer than cells on the other side. This change in the growth of a
plant in response to light is called phototropism. Phototropism is important because plants need light to carry out
photosynthesis.
7
Some plants respond to touch. For example, the Mimosa tree will close its leaves when you run your finger over them.
Another plant that does this is the commonly known prayer plant. When touched, it folds its leaves together like hands
folded in prayer. Vines of beans, peas, and other plants will grab onto and grow upward along a vertical support to
maximize the amount of sun they receive. The response of a plant to touch is called thigmotropism (thig-mo-TROP-pizum).
8
Plant adaptations have occurred over thousands and millions of years. These adaptations started as very small
changes. A plant may have been changed somehow to grow a little taller. This change would have helped it to reach into
the sunlight a little higher than other plants around it. When survival is the goal, even the smallest advantage is important.
This little difference in height might have helped the plant have a better chance of surviving and reproducing than the
shorter plants around it.
9
When the plant reproduced, the characteristic would have been passed on to its offspring. As generation after
generation passed, there may have been another change that allowed another one of these offspring to reach even
higher. This is how the process of evolution works. These slow, gradual changes over time give certain organisms a
characteristic that lets them survive to reproduce better than others of its species. These organisms produce offspring that
are better able to survive. The organisms without the characteristic gradually die off and are replaced by the ones who
have it. This process that favors the better adapted organism is called natural selection.
10
Copyright © 2016 edHelper
Name _____________________________
Date ___________________
Plant Behaviors and Evolution
1. Name at least three things that plants need to survive.
2. Plant adaptations increase the chances that ______.
Plants will keep growing bigger and bigger.
Plants will have more fruits.
Plants will have more flowers.
Plant species can survive in their habitat.
3. What is a tropism?
Plant growth in response to a stimulus
Growing toward water
Growing toward a taller plant
Any change in a plant or animal
5. In gravitropism ______.
Roots always grow toward the center of the earth
Stems always grow away from the center of the
earth
Both a and b are correct
None of the above
4. What is gravitropism or geotropism?
A plant's growth in response to gravity
A plant growing toward sunlight
A plant growing toward water
A plant closing its leaves
6. You put a plant in a sunny window. In a few days, you
notice that most of the leaves are now turned toward
the window. Which tropism is this an example of?
Gravitropism
Geotropism
Phototropism
Thigmotropism
7. When peas or bean plants grab onto a vertical support 8. The process that favors the better-adapted organism is
and grow upward, this is an example of ______.
Gravitropism
Thigmotropism
Geotropism
Phototropism
called ______.
Evolution
Tropism
Adaptation
Natural selection
Name _____________________________
Date ___________________
Plant Behaviors and Evolution
Explain how a plant can change in response to its environment.
Name _____________________________
Date ___________________
Plant Behaviors and Evolution
Explain how the process of natural selection works.
Plant Behaviors and Evolution
By Cindy Grigg
photosynthesis
happening
compounds
phototropism
better
stimulus
response
stimuli
thigmotropism
evolution
happen
maximize
geotropism
happened
generation
gravitropism
tropism
advantage
Directions: Fill in each blank with the word that best completes the reading comprehension.
When you look at a plant, you may not see much (1) _______________________ . But, like people and animals, plants
have needs. Living things can live on Earth because Earth has certain things that allow them to grow and reproduce. Plants need
light, air, water, and space.
Plants also need nutrients, or certain substances found in soil, to live. Some nutrients come from rocks which are filled with
minerals. Minerals are not living, but they contain (2) _______________________ that plants use as nutrients. These nutrients
become part of the soil when rock minerals break up into very small pieces and dissolve. A plant takes in nutrients through its roots
along with water.
Plants also get nutrients from other living things. When plants and animals die, they decay and release their nutrients which then
return to the soil. This is why putting dead leaves or grass clippings on your garden is good for it.
Plants that live in different habitats have different traits that allow them to survive there. Over time, adaptations, or changes, in
plant parts have (3) _______________________ . They continue to (4) _______________________ to increase the chances that
plant species can survive in their habitat. Adaptations are what make the sizes and shapes of plant parts different.
Plants can't move like animals can, but they can respond to a stimulus, or a change in the environment. Plant growth in
(5) _______________________ to a (6) _______________________ is called a (7) _______________________ . Plants respond
to (8) _______________________ such as light, gravity, water, and touch.
When you plant a seed in the soil, you don't have to worry about which direction the seed faces. Why? Because plant roots respond
to gravity. They will always grow down toward the center of the earth. Stems always grow upward, away from the pull of gravity.
Plant growth in response to gravity is called (9) _______________________ (grav-ih-TROH-piz-um) or
(10) _______________________ .
If you place a plant near a window, you will notice that, eventually, most of the leaves will be facing the sun. The leaves turn when
cells on one side of the stem grow longer than cells on the other side. This change in the growth of a plant in response to light is called
(11) _______________________ . Phototropism is important because plants need light to carry out
(12) _______________________ .
Some plants respond to touch. For example, the Mimosa tree will close its leaves when you run your finger over them. Another
plant that does this is the commonly known prayer plant. When touched, it folds its leaves together like hands folded in prayer. Vines
of beans, peas, and other plants will grab onto and grow upward along a vertical support to (13) _______________________ the
amount of sun they receive. The response of a plant to touch is called (14) _______________________ (thig-mo-TROP-piz-um).
Plant adaptations have occurred over thousands and millions of years. These adaptations started as very small changes. A plant may
have been changed somehow to grow a little taller. This change would have helped it to reach into the sunlight a little higher than
other plants around it. When survival is the goal, even the smallest (15) _______________________ is important. This little
difference in height might have helped the plant have a better chance of surviving and reproducing than the shorter plants around it.
When the plant reproduced, the characteristic would have been passed on to its offspring. As generation after
(16) _______________________ passed, there may have been another change that allowed another one of these offspring to reach
even higher. This is how the process of (17) _______________________ works. These slow, gradual changes over time give certain
organisms a characteristic that lets them survive to reproduce better than others of its species. These organisms produce offspring that
are (18) _______________________ able to survive. The organisms without the characteristic gradually die off and are replaced by
the ones who have it. This process that favors the better adapted organism is called natural selection.
Copyright © 2016 edHelper
Name _____________________________
Date ___________________
Plant Behaviors and Evolution
1. Name at least three things that plants need to survive.
2. Plant adaptations increase the chances that ______.
Plants will have more flowers.
Plants will keep growing bigger and bigger.
Plants will have more fruits.
Plant species can survive in their habitat.
3. What is a tropism?
Growing toward water
Growing toward a taller plant
Plant growth in response to a stimulus
Any change in a plant or animal
5. In gravitropism ______.
Roots always grow toward the center of the earth
Stems always grow away from the center of the
earth
Both a and b are correct
None of the above
4. What is gravitropism or geotropism?
A plant growing toward sunlight
A plant's growth in response to gravity
A plant closing its leaves
A plant growing toward water
6. You put a plant in a sunny window. In a few days, you
notice that most of the leaves are now turned toward
the window. Which tropism is this an example of?
Gravitropism
Phototropism
Thigmotropism
Geotropism
7. When peas or bean plants grab onto a vertical support 8. The process that favors the better-adapted organism is
and grow upward, this is an example of ______.
Thigmotropism
Gravitropism
Phototropism
Geotropism
called ______.
Adaptation
Tropism
Natural selection
Evolution