Plant Diversity: Evolution, Structure, and Reproduction in Biology

What are the four groups of land plants?

Bryophytes, seedless vascular plants (ferns), gymnosperms, and angiosperms.

What are the benefits of terrestrial life for plants?

Access to sunlight, CO2, and fewer herbivores compared to aquatic environments.

What challenges do plants face when living on land?

Desiccation, structural support, and reproduction without water.

What is the significance of charophytes in relation to plants?

Charophytes are the closest protist relatives of plants, sharing a common ancestor.

What is alternation of generations in plants?

A reproductive cycle where plants alternate between haploid gametophyte and diploid sporophyte generations.

How do bryophytes differ from seedless vascular plants?

Bryophytes are non-vascular and have a dominant gametophyte stage, while seedless vascular plants have vascular tissue and a dominant sporophyte stage.

Give examples of bryophytes.

Mosses, liverworts, and hornworts.

What is a key characteristic of seedless vascular plants?

They have vascular tissue and flagellated sperm that require water for fertilization.

What are gymnosperms?

Seed plants that produce seeds not enclosed in an ovary; examples include conifers.

What are angiosperms?

Seed plants that produce flowers and fruits, with seeds enclosed in an ovary.

What geological period saw the dominance of bryophytes?

Bryophytes were prominent during the first 100 million years of plant evolution.

What adaptations do plants have for life on land?

Cuticle for water retention and stomata for gas exchange.

What is the role of rhizoids in bryophytes?

Rhizoids anchor gametophytes to the substrate but do not function as true roots.

How do bryophytes reproduce?

They require water for sperm to swim to the egg for fertilization.

What is the ecological importance of mosses?

Some mosses contain nitrogen-fixing bacteria and form peat, which is a significant carbon reservoir.

What is the significance of vascular tissue in plants?

Vascular tissue (xylem and phloem) allows for efficient transport of water, nutrients, and food, enabling plants to grow taller.

What are sporophylls in ferns?

Sporophylls are modified leaves that bear sporangia, where spores are produced.

What is the difference between homosporous and heterosporous plants?

Homosporous plants produce one type of spore, while heterosporous plants produce two types of spores that develop into male or female gametophytes.

What adaptations do seed plants have?

Reduced gametophytes, heterospory, ovules, and pollen.

What is the role of pollen in seed plants?

Pollen allows for the transfer of male gametes without the need for water.

What is the significance of the Carboniferous period for seedless vascular plants?

The ancestors of modern seedless vascular plants formed the first forests during this period, leading to the formation of coal.

What is the life cycle of a moss?

The life cycle includes a dominant gametophyte stage that produces gametes, leading to fertilization and the formation of a sporophyte.

What is pollination?

The transfer of pollen to the part of a seed plant containing the ovules.

How can pollen be dispersed?

Pollen can be dispersed great distances by air or animals.

What happens if a sperm fertilizes the egg of a seed plant?

The ovule will develop into a seed.

What is a seed?

A sporophyte embryo (2n) with its food supply, packaged in a protective coat.

What are the advantages of seeds?

Seeds can remain dormant until conditions are favorable, have a supply of stored food, and can be transported long distances.

What does the term 'gymnosperms' mean?

It means 'naked seeds' and refers to seed plants that bear seeds typically on cones.

Name the four phyla of gymnosperms.

Cycadophyta, Ginkgophyta, Gnetophyta, and Coniferophyta.

What are the key features of the gymnosperm life cycle?

Reduced gametophyte, transfer of sperm to ovules by pollen, and production of seeds.

What is the role of pollen cones in pine trees?

Pollen cones produce microspores that develop into male gametophytes.

What do ovulate cones contain?

They contain megaspores that develop into female gametophytes.

During which era did gymnosperms dominate terrestrial ecosystems?

During the Mesozoic era, 252 to 66 million years ago.

What is unique about the phylum Cycadophyta?

Cycads have large cones and palmlike leaves, and they possess flagellated sperm.

What is the only extant species in the phylum Ginkgophyta?

Ginkgo biloba.

What are the three genera in the phylum Gnetophyta?

Gnetum, Ephedra, and Welwitschia.

What is the largest phylum of gymnosperms?

Coniferophyta, which includes about 600 species.

What does 'angio' mean?

'Angio' means vessel, referring to the structure of angiosperms.

What are the two key adaptations of angiosperms?

Flowers and fruits.

What is the function of a flower in angiosperms?

It is specialized for sexual reproduction.

What are the four types of floral organs?

Sepals, petals, stamens, and carpels.

What is double fertilization in angiosperms?

One sperm fertilizes the egg, while another combines with two nuclei in the central cell to form endosperm.

What are the two main groups of angiosperms?

Monocots (one cotyledon) and Eudicots (two cotyledons).

What is the significance of staple crops?

They yield 80% of the calories consumed by humans.

What are some examples of staple crops?

Wheat, rice, maize, potatoes, cassava, and sweet potatoes.

What is the role of fruits in angiosperms?

Fruits protect seeds and aid in their dispersal.

How do seeds disperse?

Seeds can be carried by wind, water, or animals to new locations.