Ch 5

. Understand the life cycle of pine, as illustrated by the lecture slides and the video that we watched during the lecture. Compared with mosses and ferns, why do we say that conifers are better adapted to land or terrestrial environments

(1) Conifers use seeds for dispersal, which contains embryonic sporophyte with seed coat protection and nutrients that help germination. Mosses and ferns use spores for dispersal, not advantageous at all, because spores will develop into gametophytes, which will need fertilization when gametophytes are mature to generate sporophytes. Also read the answers for the question 03. (2) Non-vascular gametophyte is further reduced and simplified in conifers. In gymnosperms, gametophyte is further reduced in size and not obvious as in mosses and ferns. For example, in conifers, female gametophyte is inside the ovule, not visible outside at all. Male gametophyte in pine is represented as the tiny pollen grain. Now, gametophyte develops on the sporophyte. It relies on sporophyte. This is very different from ferns and mosses. Fertilization does not need water any more in conifers. How? The pollen tube will be developed to facilitate fertilization.

Ginkgo biloba is also a living fossil, because its close relatives can be only found as in fossil records.

(1) It originates in China, and it is the only plant with special fan-shape leaves. (2) It is a living fossil that its close relatives only exit as in fossil records (270 million years ago). With its phylum, it has a single class, single order, single family, single genus and single species - Ginkgo biloba. (3) Ginkgos are dioecious, with separate sexes, some trees being female and others being male. (4) It contains chemicals used for memory and concentration enhancer. (5) It has a superior capability to resist air pollutants, in comparison with many other plants.

heterospory

: the condition of producing microspores and megaspores. In seed plants, two types of spores are produced: one is bigger (female spore) and the other is small (male spore).

. Clearly understand the differences among gametes, spores and seeds. Do mosses, ferns, gymnosperms (conifers) and angiosperms (flowing plants) produce gametes, spores and/or seeds?

All these four groups of plants produce gametes (eggs and sperms), all of them produce spores, but only gymnosperms and angiosperms produce seeds. (2) Gametes and spores are haploid whereas seeds are diploid and mixed. (3) Seeds will develop into new sporophytes whereas spores will develop into gametophytes. Gametes (egg and sperm) must meet to finish fertilization and result in a zygote, which will develop into sporophytes. Without fertilization, both sperms and eggs will die. Both seeds and spores can survive for a long time, and can be dispersed over a long distance. (4) Gametes are single cells. Most spores are single cell and some spores have a few cells. Seeds are multiple-cell structure that contains a baby sporophyte with nutritive tissue (i.e., some gametophyte tissues) and protective coat. (5) As for dispersal manners, seeds can be dispersed by wind, water and animals including insects. Spores are mainly dispersed by wind, sometimes by water.

The dominant life stage for gymnosperms can best be described as:

Diploid sporophyte

were the first group of plants not to have swimming sperms and were freed from the need for water to reproduce

Gymnosperms

ovule

In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It is a rudimentary seed containing, before fertilization, the female gametophyte, with archegonia and egg cell, all being surrounded by integument (protective layers). It consists of three parts: the integuments forming its outer layer, megasporangium, and the megaspore-derived female gametophyte (or megagametophyte) in its center. After fertilization, ovule contains embryonic sporophyte and will develop into seeds while integument develops into seed coat.

In conifers, which of the following is correctly paired?

Pollen - Microgametophyte

gymnosperm

Seed plants that produce naked seeds that are not enclosed inside a fruit are called

How many sub-groups of plants exist within gymnosperms? Which one has leaves that look like palm tree or fern frond? Why maidenhair tree (Ginkgo biloba) is special? Which plant is the oldest living plant in our planet? How old is it?

There are four subgroups: conifers, cycads, ginkgo and gnetophyte. Cycads are long-lived trees native to tropical regions with palm-like or frond-like leaves. Coconut palm tree belongs to flowering plants (monocot). It is different from Cycad. In fact cycads are the oldest living seed bearing plants in the world. Dating back over 230 million years, cycads virtually unchanged for some 90 million years. Thus the name "Living Fossils" has been used to describe these ancient relicts of a bygone era, when dinosaurs were the main seed distributors.

The ovule of the pine consists of:

a megasporangium and its integument layer.

A pine tree is __________.

a sporophyte

cones

are plant reproductive structures or organs that contain gametangia: archegonia or antherida, where gametophytes will develop.

pollen

are the immature male gametophytes existing in seed plants.

conifers

belong to one sub-group of Gymnosperms, and have about 550 species. are cone bearing plants.

pollen tube

cell is one of the cells of the pollen grain, and it directs the growth of the X that is important to finish fertilization in seed plants. In seed plants, no water is needed to finish fertilization.

The tree with fan-shaped leaves that are often divided into two lobes is the:

gingko tree

seed

is a reproductive and dispersal unit containing an embryonic sporophyte and nutritive tissue surrounded by a protective X coat. In x plants, spore is not important anymore for dispersal purpose. Instead, X are important for plant dispersal.

Megasporangium

is a sporangium that bears megaspores.

microsporangium

is a sporangium that bears microspores

Megaspore

is a spore that gives rise to a female gametophyte. Usually it is bigger in size in comparison with microspores

Microspore

is a spore that gives rise to a male gametophyte

living fossil

is a term for any living species (or clade) of organism which seems to be the same as a species otherwise only known from fossils. Living fossil species usually has no or a few close living relatives.

Spermatophyte

is plant that creates seeds, including both Angiosperms (flower plants) and Gymnosperms.

Megasporocyte

is the megaspore mother cell, a diploid cell where meiosis will occur and result in four megaspores.

microsporocyte

is the microspore mother cell, a diploid cell where meiosis will occur and result in four microspores (haploid).

In conifers, what cell goes through mitosis in order to become a mature female gametophyte?

megaspore

The name gymnosperm is derived from the Greek words meaning:

naked seed

Pollination

process by which pollen grain is transferred in plants, thereby enabling fertilization and sexual reproduction

In pine trees, the immature male gametophyte is ______.

the pollen grain

In pine trees, the mature male gametophyte is __________.

the pollen tube with its included nuclei