Lets talk about Sex!

1
Lets talk about Sex!

• Sexual reproduction that is

2
3 stages

1. Mating
2. Fertilization
3. Development

3
Mating

• Process by which gametes can meet.
• Mating Seasons (heat) for optimal times for
  fertilization to occur
• Depending on species, mating can occur on land,
  in water, or in air.
• Some animals mate a few times a year to once
  every few years.

4
Fertilization

• Recall union of sperm (male gamete) and egg
  (female gamete)
• Once egg is fertilized
• --gt cell division occurs if conditions are met.
• Temperature optimal (enzyme and proteins only
  function properly in certain temp)
• Nutrients adequate (growth of embryo)
• Sufficient moisture (prevent drying out)
• Protection from predators and harmful substances

5
External Fertilization

• Sperm and egg unite outside bodies of parents
• Common in animals that live in water
• Releasing of gametes in water called spawning
• Both males and females produce huge amounts of
  gametes.
• What dangers or difficulties lie in spawing?

6
External Fertilization

• Why is it common in species that live in water?
• What do mosses and ferns require in order for
  external fertilization to occur?
• What advantages does external fertilization have?
  Disadvantages?

7
External Fertilization

• Advantages
• Little energy to find mate
• Large numbers of offspring produced
• Genetic Diversity
• Little chance egg will be fertilized by sperm of
  parent

• Disadvantages
• Many offspring do not survive
• Unprotected embryos
• Few survive until adulthood
• Some species die after fertilization

8
Internal Fertilization

• Sperm cells are deposited inside females body
• Humans more than 1,000,000 sperm cells will be
  deposited, about 100 will meet egg.
• Once sperm penetrates egg, membrane changes
  electrical charge --gt prevents another sperm from
  entering. Why is this important?

9
Internal Fertilizaton

• Advantages
• Protected from predators (inside mother)
• Increased rate of survival

• Disadvantages
• Huge amounts of energy for finding a mate
  (complex behaviors) and creating offspring
  (growing inside and protection)
• Fewer offspring created.

10
Internal and External Fertilization

• Complete worksheet.
• Due tomorrow.
• Quiz??