Biology: Diversity of Life

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  • Topic: Plant, Fungus, Flowering plant
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Biology:
Unit 1: Diversity Of Life
Fungi
Fungi: are multi-cellular heterotrophs that use external digestion, and often grow out of sight, underground → fungi have nothing in common with plants other then the fact that they are stationary, and grow in the ground. They are not photosynthetic, and they do not produce their own food. Characteristics/ Cell Structure:

* Mesh like bodies, composed of branching networks of filaments called mycelium * Mycelium: a branched mass of hyphae
* Hyphae are thin filaments that make up the body of a fungus, they consist of long tubes of cytoplasm containing many nuclei * Cytoplasm is contained in a cell wall made of chitin

Life Cycle
Haploid: a single set of unpaired chromosomes
Diploid: two complete sets of chromosomes from each parent
Dikaryotic: a cell containing two separate nuclei

* The life cycle of most fungi involve the haploid individuals that reproduce both sexually and asexually

1. Spores produce hyphae with haploid nuclei
2. Hyphae fuse together to form Dikaryotic cell
3. Hyphae grow into large mycelium
4. Mycelium matures into mushroom cap with gills
5. Basidium on gills produces spores
6. Haploid nuclei fuse to form diploid zygote
7. Zygotes produce new haploid nuclei which becomes basidiospores (released as spores) Zygote: formed by the fusion of two different sex cells, such as sperm and an egg Importance
* Fungi, along with bacteria are the major decomposers on Earth, they are responsible for the cycling of nutrients throughout the biosphere * Fungi as well engage in symbiotic relationships with plants * Plants rely on fungi to help obtain nutrients from the soil * Without the help of fungi, the plant growth and productivity would decrease severely Environment Impact

* Fungi are responsible for some animal and plant diseases * Fungi can rot wood, and damage buildings
* The introduction of non-native fungi species have had serious consequences to the environment, in some cases it destroyed a forest of trees Plants
Plants: All plants are multi-cellular eukaryotes and obtain their food from the process of photosynthesis; plants support virtually all-terrestrial food webs. History
* Plants appeared on land about 400 million years ago
* They adapted from aquatic to terrestrial environments as they had the advantages of a greater availability of light and a more rapid diffusion of carbon dioxide/oxygen in and out of their cells * Evolved from a green group of algae

Characteristics
* All plants have cell walls made up of cellulous
* Just as fungi, plants are stationary and cannot move
* They obtain their energy by the process of photosynthesis * The three main parts of the plant are: the root, stem and leaf systems, the root secures the plant, the stem provides height and acts as a transport tube and the leaf is a surface area to collect light * All plant types look differently and are very diverse

Alterations of Generations
* The plant life cycle has diploid and haploid states, the diploid generation produces spores and the haploid generation produces gametes * A plant in the diploid stage is called a sporophyte, the diploid cells in this plant divide by meiosis to produce haploid cells * In plants haploid cells produce asexual spores

* As the haploid generation is in process, the spores grow into gametophyte individuals * The gametophytes mature and produce haploid sex cells- gametes * These gametes undergo fertilization to form diploid zygotes, zygotes then grow into sporophyte individuals and the cycle continues

→ there are 4 major groups of plants:
1. Bryophytes
2. Lycophytes and Pterophytes
3. Gymnosperms
4. Angiosperms
Bryophytes
* Are the simplest of land plants, they include mosses, liverworts and hornworts * Bryophytes have a protective cuticle and stomata for gas exchange, they don’t however have vascular...
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