3 - Asexual Reproduction WS

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Mr. Storie 10S Science Reproduction – Asexual methods

Forms of Asexual Reproduction

In all the forms of

asexual reproduction

, there is just one parent. The unicellular organisms of the

Protista

kingdom, such as the amoeba, reproduce asexually by standard

mitosis

. Members of the

Monera

kingdom, such as bacteria, are single-celled organisms that do not contain a true nucleus. Bacteria reproduce asexually by a process called

binary fission

.

Yeast cells are

unicellular

fungi that reproduce asexually by

budding.

In the budding of yeast, the parent cell pushes out part of its wall forming a bulge or bud. Then the nucleus divides by

mitosis.

One of the two new nuclei moves into the bud and the other one stays inside the parent cell. After a new wall forms between the two nuclei, the daughter cell may remain attached to the parent, or it may break away and produce a new yeast culture.

In binary fission, the parent cell divides equally into two daughter cells. In budding the

parent cell

divides unequally. The

daughter cell

is smaller than the parent cell. But after budding is complete, the daughter cell may grow to the size of the parent.

Organisms of the kingdom

Fungi

, such as the mould

Penicillium

and mushrooms, also reproduce by

sporulation

. The formation of spores or sporulation is another form of asexual reproduction. In sporulation, the parent organism produces a large number of

spores

. Each spore is a cell that was formed by mitosis and contains the same number and kinds of chromosomes as the parent cell.

Moulds grow in thin web-like strands called

hyphae

. The hyphae grow over the surface of the food (

bread

) and eat the food for energy. Sporangia form on the tips of the hyphae that have grown across the surface. In each sporangium, hundreds of spores develop by mitosis.

Vegetative propagation

is a kind of asexual reproduction that can take place in any of the growing parts of plants. These parts may be roots, leaves, or stems, including the kinds of underground stems called

tubers

and bulbs. A potato is an example of a tuber, and an onion is an example of a bulb.

The root of a carrot or turnip (

the part we eat

) placed in water will grow into a new plant. Strawberry plants propagate themselves by stem-like structures called

runners.

A runner takes root and produces a new plant.

Many house plants, such as

geraniums

may be grown from stem

cuttings

placed in water. Bulbs of onions and tulips grow into complete new plants. The tubers of potatoes and yams sprout new plants from their

eyes.

In the kingdom

Animalia

, animals are divided into two main groups –

vertebrates

and

invertebrates

.

Invertebrates, such as sponges, jellyfish, worms, shellfish and insects, make up about 97% of all animal species. Most invertebrates can reproduce by asexually means. Some animals are able to replace or

regenerate

a lost part. Lizards, starfish and planeria, can regenerate whole limbs. Lobsters can regenerate a lost claw. One arm of a starfish can re-grow a whole new body. Examples like these are sometimes called

fragmentation

, and are another example of asexual reproduction.

Mr. Storie 10S Science Reproduction – Asexual methods

DIAGRAM STUDIES

A.

On the line below each diagram, write the type of asexual reproduction that is shown. Choose from the following:

sporulation budding regeneration binary fission

2.

1.

3.

4.

B.

One the line below each diagram, write the type of vegetative propagation that is shown. Choose from the following:

tuber bulb leaf runner stem

5.

6.

7.

8.

Mr. Storie 10S Science Reproduction – Asexual methods

QUESTIONS

A.

Decide whether each statement is true or false. Write

T

or statement is false, correct the underlined word or phrase.

F

on the line before each statement. If the

____ 1. In vegetative propagation, the new plant has the same chromosomes as the parent plant.

____ 2. A form of asexual reproduction in bread mold is binary fission

.

____ 3. Regeneration is a form of asexual reproduction in the starfish.

____ 4. A lobster can grow a new claw by sporulation.

____ 5. In budding, the nuclei of the parent cell and daughter cell are different.

____ 6. The spores of a potato can sprout into a new plant.

____ 7. A strawberry plant can reproduce by runners.

____ 8. An amoeba has no true nucleus and reproduces by binary fission.

B.

In each blank write the word that will make the sentence true. Use the words below:

Mitosis cutting bulbs root tubers equally unequally fungi

1.

2.

3.

4.

5.

6.

7.

8.

C.

A group of organisms that can reproduce by spores are the ____________________.

In carrots, the organ of vegetative propagation is the ________.

The _________ of tulips and onions can grow into new plants.

In budding, the parent cell divides ___________________.

Geraniums may be reproduced from stem _______________.

In binary fission, the parent cell divides _________________.

Write simple diagrams to show the steps of Mitosis.

Yams are a kind of underground stem called _______________.

A amoeba cell nucleus divides by ______________.

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