Log In Start studying!

Select your language

Suggested languages for you:
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|
Plants

Have you ever stopped and smelled flowers? Enjoyed a stroll down a park and looked at the changing leaves? If so, you've enjoyed the presence of plants on this planet. Plants are varied organisms that we humans often encounter in parks, streets, crosswalks, and even stores.

During holidays, Christmas trees and mistletoes can be seen everywhere. Many other people use plants like roses, lilies, and orchids to decorate their lawns and yards daily. Continue reading to learn facts about plants that will "leaf" you wanting more!

  • First, we will look at the definition of plants.
  • Then, we will dive into the characteristics of plants.
  • After, we will mention some examples of plants and their importance.

Definition of Plants

Plants are thought to have evolved from green algae around 470 million years ago (mya) during the Ordovician period. The closest living relatives to land plants today are known as charophytes, a type of green algae.

Plants are eukaryotic organisms belonging to the Plantae kingdom. They can grow on land or in water.

Eukaryotes are mainly multicellular organisms with membrane-bound organelles, compared to prokaryotes, like archaea and bacteria.

There are around 250,000 plant species known to us. Plants that grow on land are terrestrial or land plants (embryophytes). In contrast, plants that grow in the water are called aquatic plants (hydrophytes).

The first plants are thought to have been similar to current liverworts and mosses. This means that they were non-vascular and had shallow roots.

If a plant is classified as non-vascular, they don't have specialized structures for transporting nutrients and water throughout their bodies. These plants fall under the category of bryophytes. Bryophytes are considered the earliest land plants.

After bryophytes, pteridophytes evolved. Pteridophytes include ferns, horsetails, and lycophytes. They are known for being vascular plants that disperse spores.

Once pteridophytes evolved, gymnosperms came next. Gymnosperms are the first land plants with seeds, including conifers, Ginkgo, and cycads.

Angiosperms, the most common type of green plant, came after gymnosperms. They also have seeded plants, except they produce flowers and fruits and contain endosperm. The endosperm is a tissue that encompasses and gives nutrients to the embryo within its seeds. Since gymnosperms have no flowers or fruits, they have naked seeds.

Aquatic plants include plants like the water lily and the lotus. They are plants that are either fully submerged or floating in the water. Aquatic plants are thought to have emerged from terrestrial plants. Algae are not considered aquatic plants because they don't have true leaves, roots, and stems. We will go over the plants' structures in detail in the section parts of plants.

Characteristics of Plants

The following are the defining characteristics of land and aquatic plants.

Characteristics of land plants:

  • They are autotrophic organisms that make their food from chemical substances. They do this through the process of photosynthesis, which uses light energy to convert carbon dioxide \((CO_2)\) and water \((H_2O)\) into carbohydrates or sugars. Plants specifically store their food as starch, a complex carbohydrate.

  • Land plants contain chlorophyll, a green pigment that allows plants to capture sunlight and convert it into chemical energy.

  • Plants have cell walls that are made of cellulose. Cellulose is the most common complex carbohydrate made of glucose molecules bound together. Glucose is a simple carbohydrate or building block of carbohydrates.

  • These plants are not motile or cannot move. They are oriented in one place by their roots but can respond to the sun or touch. When plants move in the sun's direction, this is called heliotropism.

  • Tropism occurs when living things grow or move in response to environmental stimuli. An example of tropism is heliotropism.

  • A plant's life cycle can be described as an alternation of generations. We will go over this more in-depth under the section reproduction of plants.

  • Most of the plants are terrestrial; they make up around 80% of the planet's biomass. Land plants include bryophytes, pteridophytes, gymnosperms, and angiosperms. Angiosperms are the most diverse and common type of terrestrial plants.

  • All land plants have adaptations to help them survive on land. They have waxy cuticles, root-like structures or roots, stomata, association with fungi, and life cycles that alternate. We will dive into this topic more deeply in the following few sections.

Characteristics of aquatic plants:

  • Pine trees

    • Since there are many trees, we'll focus on pine trees which are gymnosperms.

    • Pine trees are evergreen, coniferous trees with resin that live in sandy and dry soils.

    • The branches are arranged in whorls or ordered in circles around the trunk; a new whorl is added each year.

    • Pines, on average, live around 400 years, and white pines are the most common type since people often use them as Christmas trees.

    • White pines typically have short and shiny needles, occur in groups of five, and have long and slender cones.

    • Resin is a viscous substance excreted by plants that protect them from insects and other pathogens. Resin can be used as glue or adhesives in construction and buildings commercially.

  • Roses

    • Instead of focusing on all flowers, we'll narrow the scope to one of the most well-known flowers: roses. Roses are angiosperms or flowering plants.

    • Roses are plants that belong to the family Rosaceae and are native to temperate regions of the Northern Hemisphere.

    • People commonly associate roses with thorns, but they do not have thorns; instead, they have prickles to help protect them against predators attracted to their sweetly scented fragrance.

    • Roses come in various colors, with red roses being the most common due to their symbol of romance.

Importance of Plants

Through photosynthesis, plants provide us with oxygen. It's estimated that one large tree can give around four people oxygen to breathe and survive. Plants also absorb carbon dioxide, a greenhouse gas that has increased global warming due to humans burning fossil fuels for gas and energy.

Plants also provide other animals and us with food, shelter, medicine, fuel, etc.

Plants are primary producers that we need to consume to obtain energy. Examples of plants we eat for energy are potatoes, bananas, and other vegetables and fruits. Meats we eat, such as beef, must also consume plants like grass. Without plants, we would not have many different animals to consume.

Primary producers are autotrophs who can make their own food instead of consuming it. Examples are photoautotrophs, such as plants, that can produce chemical energy from sunlight.

Plants and animals also have a mutualistic, or interdependent, relationship from which both benefit. For instance, bees are pollinators that flowering plants rely on to reproduce.

Plant matter has the potential to work as biofuels or renewable sources of energy that could replace fossil fuels. This means that plants could potentially power our future without all the contamination from burning fossil fuels, which cannot be renewed.

The ironic part is that fossil fuels were made from decomposing plants and animals over millions of years underground.

Symbiotic relationships are any biological interaction between two different organisms. Most of these interactions are often long-term. An example of a symbiotic relationship is mutualism.

Mutualism is a symbiotic relationship in which both organisms benefit.

Other notable types of symbiotic relationships include commensalism and parasitism. Commensalism is where one organism benefits and the other one remains unaffected. In comparison, parasitism is where one organism benefits and the other is harmed.

Reproduction of Plants

We'll focus on the general life cycle of plants since these details apply to all plants:

Plants' reproductive cycle can be described as an alternation of generations.

Alternation of generations means that plants go through two multicellular stages: the haploid gametophyte and the diploid sporophyte.

Gametes are mature haploids that are either male or female sex cells that fuse to form a zygote. It's equivalent to the egg cells women have and sperm men have that need to combine to produce a zygote.

Spores are unicellular reproductive cells that can grow into a new individual without sexual reproduction or fusion.

The gametophyte or multicellular haploid stage makes gametes via a process called mitosis. They combine to form a diploid zygote. The zygote then grows into a multicellular and diploid sporophyte that produces haploid spores through a meiosis process. The haploid spores then develop into gametophytes again, as shown in Figure 3.

The alternation of generations does differ in different types of plants:

Frequently Asked Questions about Plants

The four types of plants are bryophytes, pteridophytes, gymnosperms, and angiosperms.

Plants are eukaryotic organisms belonging to the Plantae kingdom. They can grow on land or water.  

Plants are eukaryotic organisms belonging to the Plantae kingdom. They can grow on land or water. Examples include roses, pine trees, etc. 

Plants provide us with oxygen, food, and shelter. 

The five main groups plants are divided into are bryophytes, pteridophytes, thallophytes, gymnosperms, and angiosperms. 

Plants are eukaryotic, have tropism, can grow and reproduce, are autotrophs, have cell walls, and have a life cycle with an alternation of generations.

Final Plants Quiz

Question

What is a plant?

Show answer

Answer

Plants are eukaryotic organisms belonging to the Plantae kingdom. They can grow on land or water. 

Show question

Question

What molecule is cellulose made of?

Show answer

Answer

glucose

Show question

Question

What is tropism?

Show answer

Answer

When plant responds to the external environment.

Show question

Question

What is NOT a characteristic of aquatic-based plants?

Show answer

Answer

Their fruit is inedible when exposed to oxygen.

Show question

Question

What do roots help deliver to the rest of the plant?

Show answer

Answer

Nutrients and water

Show question

Question

What are leaves mostly known for in the plant system?

Show answer

Answer

Photosynthesis

Show question

Question

Fruits protect which part of the plant?

Show answer

Answer

Seeds

Show question

Question

Which plant is non-vascular, flowerless and reproduces through spores?

Show answer

Answer

moss

Show question

Question

What is main reason to revere plants?

Show answer

Answer

They provide oxygen.

Show question

Question

What are gametes?

Show answer

Answer

Mature haploids that are either male or female sex cells that fuse to form a zygote.

Show question

Question

Which ways do spores reproduce?

Show answer

Answer

Unicellular Reproduction 

Show question

Question

When does double fertilization occur?

Show answer

Answer

When one sperm cell fertilizes the egg cell while the other sperm cell combines with two polar nuclei to form an endosperm.

Show question

Question

Which two multicellular phases are gone through during the alternation of generations?

Show answer

Answer

haploid gametophyte

Show question

Question

Plants are considered renewable energy resources.

Show answer

Answer

True

Show question

Question

Paper is made out of cellulose.

Show answer

Answer

True

Show question

Question

How are gametes, spores, sporophytes, and gametophytes involved in the life cycle of plants?

Show answer

Answer

  • Plants' reproductive cycle can be described as an alternation of generations. 
  • Alternation of generations means that plants go through two multicellular stages: the haploid gametophyte and the diploid sporophyte
  • Gametes are mature haploids that are either male or female sex cells that fuse to form a zygote. It's equivalent to the egg cells women have and sperm men have that need to combine to produce a zygote.
  • Spores are unicellular reproductive cells that can grow into a new individual without sexual reproduction or fusion.
  • The gametophyte or multicellular haploid stage makes gametes via mitosis. They combine to form a diploid zygote. The zygote then grows into a multicellular and diploid sporophyte that produces haploid spores through a meiosis process. The haploid spores then develop into gametophytes again.


Show question

Question

What type of plant is pictured below?

Show answer

Answer

Bryophytes: moss

Show question

60%

of the users don't pass the Plants quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Sign up to highlight and take notes. It’s 100% free.