The Gymnosperms and Angiosperms are groups of plants with seed, which means that they don’ t necessary acquire water for fertilization. These groups have made adaptations for sexual reproduction on dry land.
1) Gymnosperms (plants with the seeds are not enclosed in an ovary) have developed over the course of its evolution, structures that solved the main limitations present in the Pteridophytes in relation to sexual reproduction, in the terrestrial environment. The main changes that happened as an evolutionary adaptation to dry land are those on the seeds and pollen. The advantages of the seeds are: the storage tissue which sustains growth and a protective coat of the seeds. Seed is enveloped with the layers of hardened tissue which prevents desiccation. This is what frees reproduction from the need for a constant supply of water. <span>The sperm (male gamete) of gymnosperms</span> is enclosed in a pollen grain. Thi structure is protected from desiccation and can reach the female organs without dependence on water. Gymnosperms also developed structures called cupules to enclose and protect the ovule (the female gametophyte) which will develop into a seed upon fertilization.
2) Angiosperms are a group of plants which protect their seeds within an ovary called a fruit. Angiosperms have special evolutionary adaptations. For example, they produce their gametes in separate organs, usually in a flower, so the fertilization and embryo development takes place inside an anatomical structure. That provides a stable system of sexual reproduction largely sheltered from environmental fluctuations like water need.
Answer:
Mature pollen grains contain two cells: a generative cell and a pollen tube cell. The generative cell is contained within the larger pollen tube cell. Upon germination, the tube cell forms the pollen tube through which the generative cell migrates to enter the ovary.
Explanation:
Answer:
rocks are formed by chemical compositions including the including minerals in the formation, minerals are a solid substance that are present nature and can be made up of one or more elements combined together called Chemical Compounds.
Sister- identical homo.- different from eachother
Answer:
The technology that allows scientists to study the activity of many genes at once is a <u>microarray</u>.
Explanation:
A microarray is a laboratory tool which is used to detect the expressions of a thousand genes at a time and these are in the form of slides which are printed with thousands of tiny spots at a defined position, with each spot having a known DNA or a gene.
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