Big Idea

Science Standard 7.2.a: Students know the differences between the life cycle and reproduction methods of sexual and asexual organisms. Science Standard 7.5.f: Students know the structures and processes by which flowering plants generate pollen, ovules, seeds, and fruit.

 Gymnosperm – a seed plant that produces naked seeds.  Cones – gymnosperms reproductive structures.  Ovule – a structure that contains an ovum, or egg cell.  Angiosperm – a flowering plant.  Flower – the reproductive structure of an angiosperm.

 Petals – The most colorful parts of the flower.  Pollination – the transfer of pollen from a male reproductive structure to a female reproductive structure.

 Ovary – protects the seeds as they develop.  Fruit – a ripened ovary and other structures that enclose one or more seeds.  Monocots – angiosperms that have only one seed leaf.  Dicots – angiosperms that have two seed leaves.

 All gymnosperms produce naked seeds. Many gymnosperms have needle-like or scalelike leaves, and deep growing root systems.  Gymnosperms produce seeds that are not enclosed by fruits.  Gymnosperms are the oldest type of seed plants. (first appeared on earth about 360 million years ago.  Only four groups of gymnosperms exist today. (cycads, conifers, ginkgoes, and gnetophytes)

 Cycads  175 million years ago, the majority of plants were cycads  Grow mainly in the tropical and subtropical areas  Look like palm trees with cones, and cones can grow as large a a football  Conifers  The largest and most diverse group of gymnosperms today.  They are cone bearing  Keep their leaves/needles all year long  Pines, sequoias, and junipers

 Ginkgoes  Only one species exist today (ginko biloba)  Planted along city streets because they can tolerate air pollution  Gnetophytes  Live in hot deserts and tropical rainforests.  Consists of trees, shrubs and vines

 Most gymnosperms have reproductive structures called cones.  Most gymnosperms produce two types of cones. Male cones and female cones.  Male cones produce tiny grains of pollen- the male gametophyte. The pollen contains the cells that later become sperm cells  Each scale on a male cone produces thousands of pollen grains.

 The female gametophyte develops in structures called ovules.  Female cones contain at least one ovule at the base of each scale. After fertilization occurs the ovule develops into a seed.  Pollen falls from a male cone onto a female cone. A sperm cell and egg cell join together in an ovule on the female cone.

 During development, cells become fixed – or set- in how they will differentiate.  The instructions that will determine what will happen is coded in the DNA in its nucleus.  Differentiation occurs when certain sections of DNA are turned off. The active DNA then guides the development of the cell.  Once a cell’s future has been determined, when and how much it will changes depends on its DNA, its function, and the type of organism.  Some cells differentiate completely during development, others do not change until later.

 Once human cells differentiate, they usually lose their ability to become other types of cells.  Ex: a blood cell CANNOT change into a skin cell  Humans do produce cells called STEM CELLS that can differentiate throughout life.  Stem Cells exist all around the body, and respond to specific needs in the body by becoming specialized.  EX: production of red and white blood cells.

 All angiosperms share two important traits. 1 They produce flowers 2 In contrast with gymnosperms, which produce uncovered seeds, angiosperms produce seeds that are enclosed in fruits.  Angiosperms live almost everywhere on earth. They grow in frozen areas in the Arctic, tropical jungles, barren deserts, and at the oceans edge.  unlike gymnosperms, angiosperms produce fruit.

Across Discipline: Language Arts (compare and contrast the life cycles of a gymnosperm and angiosperm) Patterns: Draw and label The Structure of a flower (page 393) Question: Write a question and answer it. Different Perspectives: The differences in cell differentiation from an animal cell and plant cell Summary: Write a summary of what you have learned.

Across Discipline: Language Arts (compare and contrast the life cycles of a gymnosperm and angiosperm) Patterns: Draw and label The Structure of a flower (page 393) Question: Write two questions and answer them. Different Perspectives: The differences in cell differentiation from an animal cell and plant cell Summary: Write a summary of what you have learned.