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Chapter 2

Chapter 2 . Parents and Offspring. Lesson 1 Reproduction . Sexual reproduction - the production of a new organism from 2 parents; all mammals reproduce sexually. Fertilization - a sperm from a male and an egg cell from a female join into a single unit.

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Chapter 2

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  1. Chapter 2 Parents and Offspring

  2. Lesson 1 Reproduction Sexual reproduction- the production of a new organism from 2 parents; all mammals reproduce sexually. Fertilization- a sperm from a male and an egg cell from a female join into a single unit. Asexual reproduction- the production of a new organism from a single parent.

  3. Lesson 1 continued… Vegetative Propagation -Runners are plant stems that lie on or under the ground and sprout up as new plants; they are horizontal stems.

  4. Lesson 2: Plant Life Cycles • What are the parts of a flower? • A complete flower has all the 4 main parts: petals, sepals, stamens, and pistils

  5. Lesson 2 continued… • What is the angiosperm life cycle? • Pollination- is the transfer of pollen from the stamen to the pistil • Pollen- is the yellow powder that contains sperm cells

  6. Lesson 2 continued…. • What is in a seed? • An embryo is the beginning of a new offspring that can grow into a new plant. • Surrounding the embryo is its food supply or cotyledon . • The entire seed is surrounded by a tough outer covering called a seed coat. • Germinationis the development of a seed into a new plant.

  7. Lesson 2 continued… • What is the conifer life cycle? • Conifers include evergreens such as pines, firs, and other cone-bearing trees. • How do conifer seeds get dispersed? • The seeds are contained inside of cones • The seeds have papery, wing-like structures that help them whirl their way to the ground. • In a strong wind, these winged seeds can end up far from the tree they were launched from. • Animals can carry the seeds to new locations too!

  8. Conifer Life Cycle

  9. Lesson 3: Animal Life Cycles • What are animal life cycles? • Metamorphosis- a series of distinct growth stages that are different from one another. • Complete Metamorphosis- the process through which amphibians become adults. *In complete metamorphosis the animal goes through 4 distinct stages. 1. Egg 2. Larva 3. Pupa 4. Adult

  10. Lesson 3 continued… • Incomplete Metamorphosis • During incomplete metamorphosis the animal goes through 3 stages. • For example, a grasshopper goes through these stages • Egg • Nymph • Adult • A nymph is similar to an adult form, but it is smaller and lacks wings and reproductive structures.

  11. Lesson 3 continued… http://www.dnr.state.wi.us/org/caer/ce/eek/critter/fish/fishevent.htm • External Fertilization • External fertilization is the out-of-body joining of egg and sperm. • It is a high risk process • The chances of sperm cells finding and fertilizing the egg cells are decreased in such large amounts of water (ponds, lakes, rivers, oceans) • Many sex cells are lost and some are eaten by other animals • The sex cells can also be exposed to extreme temperature and pollution in the water. • How do these animals produce offspring in all these conditions? *By releasing a lot of sex cells at one time. This increases the chance that fertilization will occur

  12. Salmon spawning and salmon eggs

  13. Lesson 4: Traits and Heredity Eye color is inherited Building a web is an instinct in spiders • What is heredity? • Heredity- is the passing down of traits from parents to offspring from one generation to the next. • An instinct is a way of acting or behaving that an animal is born with and does not have to learn (example: a spider spinning its web).

  14. Lesson 4 continued… Recessive trait Recessive trait Dominant Trait Dominant trait • How are traits inherited? • A gene contains chemical instructions for inherited traits • A dominant trait is one that dominates, or masks, another form of that trait • A recessive trait- is one that is hidden, or masked by another form of the trait. • Each form of the trait can be represented by letters. A capital letter is used for the dominant form of the trait. A lowercaseletter is used for the recessive form of the trait.

  15. Lesson 4 continued… Mom Bb (Brown eyes) Dad Bb (Brown eyes) Brown Blue dominant recessive bb BB Bb Child receives recessive gene from both parents (Blue eyes) Child receives dominant gene from both parents (browneyes) Child receives dominant gene from 1 parent and recessive gene from the other parent (Brown eyes) • Dominant traits tend to be expressed more often than recessive traits. The recessive traits are masked by the dominant forms.

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