Science

2007-12-09T09:51:00.000-08:00

HOW DO MOSSES REPRODUCE?

Mosses reproduce in a life cycle that has two very different stages.In the two stages , mosses produce structurs that, enable them to reproduce in two different ways.

SEXUAL REPRODUCTION

Mosses look like a leafy green carpet on a forest floor. The leafy plants produce kinds of branches, male and female.They are often on the same plant, but sometimes on separate plants.These branches produce sex cells. The female branches produce eggs , which are female sex cells. The male branches produce sperm, wich are male sex cells. Sperm have structures that enable them to swim in water. Sperm swim to the sac on the female branch. When a sperm reaches an egg in a sac, the two cells join into a single cell. This joining is called a fertilization. This stage in the life cycle of the moss is called sexual reproduction. Sexual reproduction is reproduction that requires two parents.

ASEXUAL REPRODUCTION

In time the fertilized egg cell grows into a new moss plant. This is not a leafy a plant,but a thin stalk with a capsule , or spore case, at the top. Inside this case , spores are produced. This stage of the moss life cycle is called asexual reproduction. Asexual reproduction is reproduction that requires only one parent (in this case), one kind of cell , the spores. In time the spores are released and grow into a leafy moss plants . The cycle starts again.

2007-12-08T12:09:00.000-08:00

The plant kingdom

The divisions of the plant kingdom can be divided into two categories.One category contains plants that do not have veins, nonvascular plants. The other category contains plants that do have veins , wich are called vascular plants. The term vascular means "vessels", such as the blood vessels that carry blood throughout your body.

In your body , blood vessels carry nutrients to places where they are needed to help you grow and stay alive. Vascular plants also have such vessels , wich sometimes called veins or tubes. These vessels carry water and dissolved nutrients to all parts of the plant to help the plant grow and stay alive.

The plants in the first division of the plant kongdom , the liverworts ,hornworts, and mosses do not have viens. How are water and nutrients delivered to all parts of these plants?

The water and nutrients( wish are dissolved in water) pass directly from outside of the plant into their cells , and from one cell to the next.This process works well over short distances but does not work well over long distances.This is one reason why plants such as mosses are very short .

If mosses were taller , like trees , the force of gravity would prevent water from moving from cell to cell to the top of the plants.

2007-12-08T10:40:00.000-08:00

The characteristics of the five kingdoms

1-Characteristics of animals : 1-They are multicelled organisms.

2- They eat and digest other organisms.

3-Most can move from place to place.

4-They have tissues organized into organs and

organ system.

2-Characteristics of plants : 1- They are multicelled organisms.

2- They use sunlight to make their own food

(and produce oxygen).

3-Root or rootlike structures anchor th plant and

absorb water.

3-Characteristics of fungi : 1- They are mostly multicelled organisms, but there

are some one-celled organisms.

2-They cannot make their own food.

3-They absorb and digest food.

4-Characteristics of protists : 1-They are one-celled and multicelled organisms.

2 -Plantlike protists make their own food.

3-Animal-like protists take in food from their

surroundings.

5-Characteristics of bacteria : 1-Most are one-celled organisms.

2-They don't have a cell nucleus.

3-Most do not make their own food but break down

or decompose other living or once-living things.

4-Some bacteria (cyanobacteria)make thier own

food.

2007-12-05T11:09:00.000-08:00

kingdoms

Carolus Linnaeus, a Swedish scientist, developed a way of naming organisms. He gave each living thing a scientific name based on its classification. This way he could divide the kingdoms, the largest group used to classify living things, into smaller groups. Each kingdom is divided into two or more phyla. All members of a phylum share at least one important structure or other characteristic. Each phylum is divided into smaller groups called classes. Members of a class that have the most common are put into smaller groups called orders. The most similar members of an order are grouped into a family. The most similar family members are grouped into a genus. The most similar members of genus belong to a species.