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BioD Exp 6

This document summarizes and compares the key characteristics of gymnosperms and angiosperms. Gymnosperms do not produce flowers or fruit, have naked seeds not enclosed in a carpel, and use wind or insects for pollination. Angiosperms are flowering plants that have seeds enclosed in a carpel and undergo double fertilization to produce seeds. The document outlines the structures and processes of reproduction in pine trees as an example gymnosperm and compares them with the structures and fertilization process of angiosperms.

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Peter Hong Leong Cheah
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198 views2 pages

BioD Exp 6

This document summarizes and compares the key characteristics of gymnosperms and angiosperms. Gymnosperms do not produce flowers or fruit, have naked seeds not enclosed in a carpel, and use wind or insects for pollination. Angiosperms are flowering plants that have seeds enclosed in a carpel and undergo double fertilization to produce seeds. The document outlines the structures and processes of reproduction in pine trees as an example gymnosperm and compares them with the structures and fertilization process of angiosperms.

Uploaded by

Peter Hong Leong Cheah
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOC, PDF, TXT or read online on Scribd
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Experiment 6: Gymnosperm and Angiosperm

Gymnosperms
Characteristics:
1. Do not produce flower or fruit.
2. Include plants with ovules not enclosed in carpel (naked seed).
3. Absence of companion cells in phloem.
4. Heterosporous, producing microspores that develop into pollen grains and
megaspores that are retained in an ovule.
5. Fertilized by pollination through agents such as insects and wind.
6. Divided into four divisions: (i) Pinophyta (Pinus)
(ii) Ginkgophyta (Ginkgo)
(iii) Cycadophyta (Cycad)
(iv) Gnetophyta (Gnetum, Ephedra, Welwitschia)
7. Cycads and Ginkgo have motile sperms that swim directly to the egg inside the ovule,
whilst conifers and gnetophytes have sperms with no flagella. Their sperms reach the
egg cell by a pollen tube that grows through ovule tissue.
8. Pine is the most commonly studied gymnosperm. In pine, the male cone has modified
leaves called microsporophylls. Each microsporophyll bears a microsporangium within
which the microspores are produced. The microspore divides and grows to form a four-
nucleus male gametophyte which is known as pollen. A grain of pine pollen has two
large air sacs to make it buoyant in the wind. The female cone has scales called
megasporophylls that produce megaspores. During pollination, a pollen tube will grow
from the pollen to transport the sperm to the egg cell.

Figure 1: Figure 2:
The male cone of pine The female cone of pine

Angiosperms
Characteristics:
1. Flowering plants.
2. Have closed carpel enclosing the ovule.
3. Presence of companion cells in phloem
4. Heterosporangous, which produce pollens in stamen and ovules in carpel.
5. Double fertilizations: one sperm cell fuses with the egg cell forming the diploid
zygote (2n) whilst another fuses with the polar nuclei (mostly two) forming a triploid
(3n) endosperm nucleus. After double fertilizations, each ovule develops into a seed.
6. Divided into two classes: (i) Magnoliopsida (Dicots)
(ii) Liliopsida (Monocots)
7. Seeds with two cotyledons are called dicots (e.g., bean) whilst seeds contain only a
single cotyledon are monocots (e.g., corn).
1
Figure 3: The structure of a flower.

Figure 4: The differences of a monocotyledon and a dicotyledon plants.

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