Plants Science Test Flashcards

What do plants need to survive?

The lives of plants center on the need for sunlight, gas exchange, water, and minerals

The Plant Kingdom Info

Plants are classified as members of the kingdom Plantae.

Plants are eukaryotes that have cell walls containing cellulose and carry out photosynthesis using chlorophyll a and b.

What do plants need?

All plants have the same basic needs: sunlight, a way to exchange gases with the surrounding air, water, and minerals.

How are sunlight and leaves important to plants?

Plants use the energy from sunlight to carry out photosynthesis.

Leaves are typically broad and flat and arranged on the stem so as to maximize light absorption.

What is the gas exchange in plants?

Plants require oxygen to support cellular respiration, as well as carbon dioxide to carry out photosynthesis.

Plants must exchange these gases with the atmosphere and the soil without losing excessive amounts of water through evaporation.

What do plants inhale and exhale?

Plants inhale carbon dioxide, and exhale oxygen.

How have land plants evolved relating to water loss?

Land plants have evolved structures that limit water loss and speed the uptake of water from the ground.

Many plants have specialized tissues that carry water and nutrients upward from the soil and distribute the products of photosynthesis throughout the plant body.

What are minerals?

Minerals are nutrients in the soil that are needed for plant growth.

How did plants adapt to life on land?

Over time, the demands of life on land favored the evolution of plants more resistant to the drying rays of the sun, more capable of conserving water, and more capable of reproducing without water.

Origins in the Water

The ancestors of today’s land plants were water-dwelling organisms similar to today’s green algae.

Although not as large and complex as many plants, green algae have cell walls and photosynthetic pigments that are identical to those of plants. Green algae also have reproductive cycles that are similar to plants.

Studies of the genomes of green algae suggest that they are so closely related to other plants that they should be considered part of the plant kingdom.

What was the greatest challenge that early land plants faced?

The greatest challenge that early land plants faced was obtaining water. They met this challenge by growing close to the ground in damp locations.

Fossils suggest the first true plants were still dependent on water to complete their life cycles. One of the earliest fossil vascular plants was Cooksonia.

What did the first land plants evolved into?

Several groups of plants evolved from the first land plants.

One group developed into mosses.

Another lineage gave rise to ferns, cone-bearing plants, and flowering plants.

What are the four important features that botanists use to divide the plant kingdom?

Botanists divide the plant kingdom into five major groups based on four important features: embryo formation, specialized water-conducting tissues, seeds, and flowers.

What’s the relationship of plant groups?

First it starts with the plant ancestor, then embryo formation, true water-conducting tissue, seeds, and lastly, flowers (seeds enclosed in fruit)

What feature defines most plant life cycles?

The life cycle of land plants has two alternating phases, a diploid (2N) phase and a haploid (N) phase.

The Plant Life Cycle Info

Each gametophyte produces reproductive cells called gametes - sperm and egg cells. During fertilization, a sperm and egg fuse w each other, producing a diploid zygote that develops into a new sporophyte. A sporophyte produces haploid spores through meiosis. These spores grow into multicellular structures called gametophyte.

What is a sporophyte/spore-producing plant?

A sporophyte is the multicellular diploid phase.

What is a gametophyte/gamete-producing plant?

A gametophyte is the multicellular haploid phase.

What’s an important trend in plant evolution?

The reduction in size of the gametophyte and the increasing size of the sporophyte.

What are the characteristics of green algae?

Green algae are mostly aquatic. They are found in fresh and salt water, and in some moist areas on land.

What are algae?

Algae are not a single group of organisms. “Algae” applies to any photosynthetic eukaryote other than a land plant.

“Green algae” are classified with plants. (see slides 8-10 of chapter 22.2 for info on algae life cycle).

What did ancient green algae share the ocean floor with?

Ancient green algae shared the ocean floor with corals and sponges.

Where do green algae get moisture and nutrients from?

Green algae absorb moisture and nutrients directly from their surroundings and do not contain the specialized tissues found in other plants.

What factor limits the size of bryophytes?

Bryophytes are small because they lack in vascular tissues.

How do mosses stay wet/damp?

Mosses have a waxy, protective coating that makes it possible for them to resist drying, and thin filaments known as rhizoids that anchor them to the soil.

Rhizoids also absorb water and minerals from the soil.

What are some bryophyte characteristics?

Mosses, hornworts, and liverworts all belong to a group of plants known as bryophytes.

Bryophytes have specialized reproductive organs enclosed by other, non-reproductive cells.

Bryophytes show a higher degree of cell specialization than do the green algae and were among the first plants to become established on land.

Why are bryophytes small?

Bryophytes do not make lignin, a substance that hardens cell walls, and do not contain true vascular tissue.

Because of this, bryophytes cannot support a tall plant body against the pull of gravity.

Life Cycle of Bryophytes

Bryophytes display alternation of generations.

The gametophyte is the dominant, recognizable stage of the life cycle and the stage that carries out most of the photosynthesis.

The Sporophyte is dependent on the gametophyte for its supply of water and nutrients.

Bryophytes produce sperm cells that swim using flagella.

For fertilization to occur, the sperm must swim to an egg. Because of this, bryophytes must live in habitats where open water is available at least part of the year.

How are gametophytes formed (and their life cycle)?

When a moss spore lands in a moist place, it sprouts and grows into a young gametophyte.

The gametophyte forms rhizoids that. grow into the ground and shoots that grow into the air.

Gametes are formed in reproductive structures at the tips of the gametophytes.

Eggs are produced in archegonia, and sperm are produced in antheridia.

How is vascular tissue important?

Vascular tissue - xylem and phloem - make it possible for vascular plants to mvoe fluids through their bodies against the force of gravity.

Early Vascular Plants info

About 420 million years ago, plants for the first time were able to grow high above the ground.

Fossil evidence shows these plants were the first to have a transport system with true vascular tissue. Vascular tissue carries water and nutrients much more efficiently than does any tissue found in bryophytes.

What are tracheophytes?

Tracheophytes are vascular plants.

What are tracheids?

Tracheids are the specialized type of water-conducting cell that tracheophytes contain. They are hollow tubelike cells with thick cell walls strengthened by lignin. (tracheids are found in xylem). Tracheids are also connected end to end.

What is xylem?

A tissue that carries water upward from the roots to every part of a plant.

What are pits?

Pits are openings between tracheids, which allow water to move through a plant more efficiently than by diffusion alone.

What is phloem?

Phloem is the second transport tissue that vascular plants have. Phloem transports solutions fo nutrients and carbohydrates produced by photosynthesis.

What are the three phyla among the seedless vascular plants that are alive today?

Club mosses, horsetails, and ferns. The most numerous of these are the ferns.

Ferns info

Ferns have true vascular tissues, strong roots, creeping or underground stems called rhizomes, and large leaves called fronds.

Ferns can thrive in areas with little light and are most abundant in wet habitats.

Can seeds die when they don’t sprout?

Every seed contains a living plant ready to sprout as soon as it encounters the proper conditions for growth.

What adaptations allow seed plants to reproduce without open water?

Adaptations that allow seed plants to reproduce without open water include a reproductive process that takes place in cones or flowers, the transfer of sperm by pollination, and the protection of embryos in seeds.

What is gymnosperm?

The trees that produce cones.

What is angiosperm?

All flowering plants that produce fruit.

What are seeds?

A seed is a plant embryo and a food supply, encased in a protective covering. The living plant within a seed is diploid and represents the early developmental stage of the sporophyte phase of the plant life cycle.

Do today’s seed plants descend from common ancestors?

Yes, today’s seed plants are all descended from common ancestors.

The fossil record indicates that ancestors of seed plants evolved new adaptations that enabled them to survive on dry land.

Cones and Flowers info

In seed plants, the male gametophytes and the female gametophytes grow and mature directly within the sporophyte. the gametophytes usually develop in reproductive structures know as cones or flowers.

Nearly all gymnosperms bear their seeds directly on the scales of cones (gymnosperm usually pollinate by wind, and are in groups).

Flowering plants, or angiosperms, bear their seed sin flowers inside a layer of tissue that protects the seed.

Pollen info

In seed plants, the entire male gametophyte is contained in a tiny structure called a pollen grain.

Pollen grains are carried to the female reproductive structure by wind or animals such as insects.

What is pollination?

The transfer of pollen from the male reproductive structure to the female reproductive structure.

Seeds Cycle

After fertilization, the zygote contained within a seed grows into a tiny plant - the sporophyte embryo.

A tough seed coat surrounds and protects the embryo and keeps the contents of the seed from drying out.

The embryo begins to grow when conditions are right. It does this by using nutrients from the stored food supply until it can carry out photosynthesis on its own.

What are the most abundant organisms int he plant kingdom?

Flowering plants/angiosperms are the most abundant organisms in the plant kingdom, and yet they evolved much more recently than did other seed plants. The origin of flowering plants is the most recent among the origins of all plant phyla.

Flowering plants originated on land and soon came to dominate Earth’s plant life.

What are the key features of angiosperm reproduction?

Angiosperms reproduce sexually by means of flowers. After fertilization, ovaries within flowers develop into fruits that surround, protect, and help disperse the seeds.

Angiosperms develop unique reproductive organs known as flowers, shown in the figure.

Flowers contain ovaries, which surround and protect seeds.

The advantages of flowers

Flowers are an evolutionary advantage to plants because they attract animals that carry pollen with them to the next flower they visit. This means of pollination is much more efficient than the wind pollination of most gymnosperms.

The advantages of fruits

After pollination, the ovary develops into a fruit, a structure containing one of more matured ovaries. The wall of the fruit helps disperse the seeds contained inside it. The development of the multiple ovaries of a blackberry flower into the cluster of fruits that make up the one berry is shown.

When an animal eats a fleshy fruit, seeds form. the fruit enter the animal’s digestive system. by the time the seeds leave the digestive system, the animal may have traveled many kilometers.

By using fruit, flowering plants increase the ranges they inhabit.

How were angiosperms classified previously?

For many years, flowering plants were classified according to the number of seed leaves (cotyledons), in their embryos. Those with one seed leaf were called monocots. Those with two seed leaves were called dicots.

Angiosperm Classification

Scientific classification places the monocots into a single group but places the dicots in different categories:

• Amborella Clade

Only one species still exists in this oldest branch of angiosperms. Its floral parts have a spiral arrangement.

• Water Lily Clade

The water lilies are another very old group. Early water lily flowers may have been no more than 1 cm across, in contrast to the large and showy water lilies of today.

• Magnoliids

This clade contains a wide range of floral diversity, from species with rather small, plain flowers to the dinner-plate sized Magnolia flowers.

• Monocots

This clade contains about 20% of all angiosperms. Monocots include several important crop species, such as rice, corn, and wheat, as well as orchids lilies.

• Eudicots

About 75% of angiosperms are eudicots. This clade is nearly as old as the angiosperms themselves. Eudicots diversified tremendously several times in their history.

Monocots and Eudicots are tthe two main classifications of angiosperm*

How are different angiosperms conveniently categorized?

Angiosperms are often grouped according to the number of their seed leaves, the strength and composition of their stems, and the number of growing seasons they live.

What are some differences between monocots and dicots?

The differences between monocots and dicots include the distribution of vascular tissue in stems, roots, and leaves, and the number of petals per flower.

What are the characteristics of monocots and dicots?

Monocots:

• Single cotyledon

• leaves have parallel veins

• flowers have floral parts often in multiples of 3

• vascular bundles scattered throughout the stem

• fibrous roots

Dicots:

• two cotyledons

• leaves have branched veins

• flowers have floral parts often in multiples of 4 or 5

• vascular bundles arranged in a ring

• taproot

What are the two groups flowering plants are subdivided into according to the characteristics of their stems?

Woody plants are made primarily of cells with thick cell walls that support the plant body.

Herbaceous plants have stems that are smooth and nonwoody.

What are Annuals?

Plants that grow for one season

What are Biennials?

Plants that grow for two seasons.

What are Perennials?

Plants that grow for 3 or more seasons.

Characteristics of annuals, biennials, and perennials

Annuals:

• Grow from seed to maturity, flower, produce seeds, and die in just one growing season.

Biennials:

• Year 1: Sprout and grow very short stems and sometimes leaves

• Year 2: Grow new stems and leaves, flower, produce seeds, then die

Perennials:

• Most have woody stems

• Some have herbaceous stems that die each winter and are replaced in the spring.

Asexual Reproduction vs. Sexual Reproduction

Asexual reproduction is cloning and faster, but sexual reproduction creates more diversity.

What are Fungi?

• Fungi produce powerful enzymes that digest food outside their bodies, then they absorb the small molecules released.

  • Many fungi feed by absorbing nutrients from decaying matter in the soil, while others live as parasites that absorb nutrients from their host’s body. 

What is Chitin?

• Fungi have cell walls containing chitin, a polymer made of modified sugars. Chitin is also found in the exoskeletons of insects. 

What is hyphae?

Slender, branching filaments that make up the mycelium of a fungus.

• In most fungi, the cell walls divide the hyphae into compartments resembling cells. Cytoplasm and organelles can move through openings between the compartments. 

What’s actually recognized as the mushroom?

the fruiting body, or the reproductive structure.

How does the fruiting body grow?

The fruiting body grows from the mycelium

What is mycelium?

The mass of branching hyphae below the soil. Clusters of mushrooms are often part of the same mycelium, meaning they’re actually part of the same organism. 

Can fungi reproduce both sexually and asexually?

Yes, fungi can reproduce both asexually and sexually.

How do fungi reproduce asexually?

Asexual reproduction in fungi can be done by releasing spores that travel through the air and water, by breaking off a hypha, or by budding off a cell.

How do fungi reproduce sexually?

• Many of the paired nuclei fuse to form a diploid zygote nuclei that makes haploid spores during meiosis. Each spore has a different combination of parental genes and can make a new mycelium. 

• Example: In a type of bread mold, a fungus called Rhizopus stolonifer, gametes of both mating types are about the same size and are not usually called male and female. Rather, one mating type is called “+” (plus) and the other is called “-” (minus). The + and - nuclei form pairs that divide in unison as the mycelium grows. 

How can fungi disrupt the homeostasis of plants?

• Decomposition: fungi help ecosystems maintain homeostasis by breaking down dead organisms and recycling essential elements and nutrients.

• Parasitism: Parasitic fungi can cause serious diseases in plants and animals by disrupting homeostasis.

• Plant diseases caused by parasite fungi cause diseases that threaten food crops. 

What are lichens?

• symbiotic association between a multicellular fungus, a yeast, and photosynthetic organisms.

  • Lichens are often the first organisms to enter barren environments, gradually breaking down the rocks on which they grow.

  • Lichens are among the first organisms to be affected when air quality deteriorates due to their sensitivity to air pollution.

What is mycorrhizae?

• symbiotic association of plant roots and fungi

  • Researchers now estimate that 80% to 90% of all plant species form mycorrhizae with fungi— mycorrhizae gather water and nutrients from the soil and are essential to the growth of many plants. 

How do humans use mycorrhizae?

• Humans have used mushrooms and other fungi as food for thousands of years.

  • Bread and wine are both formed by the action of those single-celled fungi known as yeasts. 

Lichens and Mycorrhizae are both examples of what kind of symbiotic relationship?

Mutualistic relationships.