Where in an angiosperm would you find a megasporangium?

(A) in the style of a flower

(B) enclosed in the stigma of a flower

(C) within an ovule contained within an ovary

of a flower

(D) packed into pollen sacs within the anthers found on a

stamen

Short Answer

Expert verified

(A) The statement “in the style of a flower” isfalse.

(B) The statement “enclosed in the stigma of a flower” isfalse.

(C) The statement “within an ovule contained within an ovary of a flower” istrue.

(D) The statement “packed into pollen sacs within the anthers found on a stamen” is false.

Step by step solution

01

Angiosperms

In biology, the eukaryotic kingdom of Plantae comprises several groups of plants, angiosperms being one of them. These plants are regarded as the most evolved group due to the presence of flowers and their ability to produce fruits (seeds remain protected within this structure).

02

Explanation of option ‘(A)’

The female whorl of flowers contains pistil, formed of three parts: the style, ovary, and stigma. Pollens are received at the stigma’s sticky end and then transferred towards the ovary through the style; style is the tubular structure connecting the ovary with stigma.

Thus, style does not contain a megasporangium.

Therefore, the given statement is false.

03

Explanation of option ‘(B)’

The stigma is the uppermost end of the pistil and is functionally involved in receiving the pollens from different pollinating agents. The stigma has a sticky surface which facilitates the collection of pollens.

Thus, the stigma only has a surface for collecting pollens and does not contain megasporangium.

Therefore, the given statement is false.

04

Explanation of option ‘(C)’

The term ovary denotes the terminal portion of the pistil, and it is the structure where fertilization and development of seed occurs. The ovule lies inside the ovary; the ovule contains another structure termed megasporangium (the structure that produces megaspores).

Thus, the megasporangium is located within the ovule portion of the ovary.

Therefore, the given statement is true.

05

Explanation of option ‘(D)’

The male whorl of the flower comprises stamen, consisting of two portions, a slender filament, and a comparatively short anther. The pollens are produced with the pollen sacs (also termed microsporangia) located within the anther.

Thus, the description given in this option relates to the microsporangia and not to the megasporangium.

Therefore, the given statement is false.

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Most popular questions from this chapter

WHAT IF? Do speciation rates in closely related clades of flowering plants show that flower shape is correlated with the rate at which new species form or that flower shape is responsible for this rate? Explain.

How could phylogenies be used to help researchers search more efficiently for novel medicines derived from seed plants?

As will be described in detail in Concept 38.1, the female gametophyte of angiosperms typically has seven cells, one of which, the central cell, contains two haploid nuclei. After double fertilization, the central cell develops into endosperm, which is triploid. Because magnoliids, monocots, and eudicots typically have female gametophytes with seven cells and triploid endosperm, scientists assumed that this was the ancestral state for angiosperms. Consider, however, the following recent discoveries:

  • Our understanding of angiosperm phylogeny has changed to that shown in Figure 30.14b.

  • Amborella trichopodahas eight-celled female gametophytes and triploid endosperm.

  • Water lilies and star anise have four-celled female gametophytes and diploid endosperm.

(a) Draw a phylogeny of the angiosperms (see Figure 30.14b), incorporating the data given above about the number of cells in female gametophytes and the ploidy of the endosperm. Assume that all of the star anise relatives have four-celled female gametophytes and diploid endosperm.

(b) What does your labeled phylogeny suggest about the evolution of the female gametophyte and endosperm in angiosperms?

WRITE ABOUT A THEME: ORGANIZATION Cells are the basic units of structure and function in all organisms. A key feature in the life cycle of plants is the alternation of multicellular haploid and diploid generations. Imagine a lineage of flowering plants in which mitotic cell division did not occur between the events of meiosis and fertilization (see Figure 30.12). In a short essay (100–150 words), describe how this change in the timing of cell division would affect the structure and life cycle of plants in this lineage.

What features not present in seedless plants have contributed to the success of seed plants on land?

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