Problem 3 - Biology

Question

Which of the following statements about the fern life cycle is false? a. Sporangia produce haploid spores. b. The sporophyte grows from a gametophyte. c. The sporophyte is diploid and the gametophyte is haploid. d. Sporangia form on the underside of the gametophyte.

Step-by-Step Solution

Answer

Statement D is false.

Step 1 - Understand the Statements

Read each statement carefully and identify key terms related to the fern life cycle.

Step 2 - Analyze Statement A

Statement A: Sporangia produce haploid spores. Recall that sporangia are structures that produce spores. In ferns, these spores are haploid (n). Therefore, Statement A is true.

Step 3 - Analyze Statement B

Statement B: The sporophyte grows from a gametophyte. The fern life cycle includes the sporophyte (diploid) growing from the gametophyte (haploid), which is true. Thus, Statement B is correct.

Step 4 - Analyze Statement C

Statement C: The sporophyte is diploid and the gametophyte is haploid. Confirm that sporophytes are diploid (2n) and gametophytes are haploid (n). This statement is true.

Step 5 - Analyze Statement D

Statement D: Sporangia form on the underside of the gametophyte. Check the structure in ferns: sporangia actually form on the underside of the sporophyte's leaves, not on the gametophyte. Therefore, Statement D is false.

Key Concepts

sporophyte

In the life cycle of ferns, the sporophyte stage is essential and serves a specific role. The sporophyte is the diploid stage of the plant. This means it has two sets of chromosomes (2n).

The sporophyte grows from the fertilized egg or zygote, which emerges from the gametophyte stage.
During its growth, you will see leaves called fronds emerging from it. On the underside of these fronds, there are structures called sporangia, which are crucial for reproduction.

In summary:

• Sporophyte is diploid (2n)
• Grows from the gametophyte
• Produces spores via sporangia

gametophyte

The gametophyte stage in ferns is just as crucial, but it operates very differently from the sporophyte.

The gametophyte is haploid (n), which means it has only one set of chromosomes. This stage arises from spores produced by the sporophyte.
The structure is usually small and heart-shaped, and it carries out sexual reproduction.

On the gametophyte, you can find sex organs called antheridia (producing sperm) and archegonia (producing eggs).
After fertilization, these cells combine to form the diploid sporophyte.

In summary:

• Gametophyte is haploid (n)
• Grows from spores
• Carries out sexual reproduction

sporangia

Sporangia play a very crucial role in the fern reproductive cycle.
These structures are found on the underside of sporophyte fronds.
Each sporangium produces many spores through a process called meiosis.

These spores are haploid (n), meaning they contain only one set of chromosomes. They are later released into the environment.
Once the spores settle in a suitable location, they grow into gametophytes, thus continuing the cycle.

In summary:

• Found on the underside of sporophyte fronds
• Produce haploid spores via meiosis
• Essential for reproduction

haploid

Understanding the term 'haploid' is key to grasping the fern life cycle.
A haploid cell carries only one set of chromosomes (n).
In ferns, gametophytes and the spores produced by sporangia are haploid.

The haploid spores grow into gametophytes, which also remain haploid throughout their existence.
This stage ensures genetic diversity through sexual reproduction.

In summary:

• Haploid means one set of chromosomes (n)
• Spores and gametophytes are haploid
• Essential for genetic diversity

diploid

Another key term is 'diploid,' which is essential for understanding the fern life cycle.
A diploid cell has two sets of chromosomes (2n).
In the world of ferns, the sporophyte is the diploid phase.

The diploid stage starts when a sperm fertilizes an egg, forming a zygote.
This zygote grows into the sporophyte, which will eventually produce haploid spores.

In summary:

• Diploid means two sets of chromosomes (2n)
• The sporophyte stage is diploid
• Starts from a fertilized egg (zygote)