Biological Diversity Section 2 Reproduction and Survival

1
Biological DiversitySection 2 Reproduction and
Survival
2
2.1 A Closer Look at Variation

• Variation is one of the most critical aspects of
  species survival.
• Variation may not always be easy to identify. It
  may be a behavioural tendency or a genetic
  modification.
• Variations enable some individuals within a
  species to survive while others of the same
  species will perish.

3

• Inherited and Non-inherited Characteristics
• Inherited (heritable) characteristics are traits
  which are passed on to offspring directly from
  their parents. These traits are passed on inside
  the genetic material.
• Heritable traits include structural and
  distinguishing characteristics such as eye color,
  hair type, skin color and earlobes.

4

• Non-inherited characteristics are acquired and
  not necessarily passed on from generation to
  generation. Ex. Athleticism, artistic ability,
  leadership qualities are all learned during the
  early years of life.

5

• Discrete and Continuous Variations
• Discrete variations are differences in
  characteristics that have a definite form.
• Individuals within a species have one of two
  possible expressions of the characteristic.

6
Discrete Variation

• Hitchhiker's Thumb Straight thumb

7
Widows peak roll tongue
8

• Continuous variations are differences in
  characteristics that have a multitude of
  variations, such as height, shoe size, or hair
  color.

9

• Variation and the Environment
• Some variations may be influenced by interactions
  with the environment. These variations are not
  inherited.
• Examples include
• Change in the pigmentation of skin color due to
  sun exposure.
• Height and weight can be influenced by diet.
• Now do Check and Reflect
• p. 29 1-3, and 6

10
2.2 Asexual and Sexual Reproduction

• A. Asexual Reproduction
• Asexual reproduction involves only one parent.
• All of the offspring are identical to the parent.
  
• There are different types of asexual
  reproduction

11

• 1. Binary Fission
• only single-celled organisms reproduce in this
  way. The cell splits into two cells and each one
  is identical.
• Ex. bacteria, amoeba, algae

12

• 2. Budding
• the parent organism produces a bud (a smaller
  version of itself) which eventually detaches
  itself from the parent and becomes a
  self-sufficient individual - identical to the
  parent. Corals reproduces this way, but do not
  detach themselves
• Ex. hydra, yeast, coral, sponge

13

• 3. Spore Production
• spores are similar to seeds, but are produced by
  the division of cells on the parent, not by the
  union of two cells. One parent may produce many
  spores, each of which will grow into a new
  individual, identical to its parent.
• Ex. fungi, green algae, moulds, ferns

14
Q How do spores survive unsuitable growing
conditions? (p.30)
15

• 4. Vegetative Reproduction
• The reproduction of a plant not involving a
  seed, including cuttings, runners, suckers,
  tubers.
• Ex. coleus plant, spider plants, strawberries,
  aspen, potatoes
• Q Explain why a cluster of aspen trees turn
  color at exactly the same time (p.31)

16

• Read the infoBIT on p.30 about Parthenogenesis

17

• Q define parthenogenesis -
• In Greek it means
• List 5 organisms who may reproduce by
  parthenogenesis

18

• B. Sexual Reproduction
• Sexual reproduction usually involves two
  individual organisms (some plants and animals can
  self-fertilize).
• The offspring inherit half of their genetic
  information from one parent and the other half
  from the other parent.
• Sexual reproduction involves specialized gametes
  (reproductive cells that have only one role - to
  join with another gamete during reproduction).

19

• 1. Sexual Reproduction in Animals
• Male gametes are called sperm cells and the
  female gametes are called egg cells or ova.
• During mating, the sperm cell and the egg cell
  unite to form a fertilized combination of cells
  called a zygote.

20

• The zygote divides first into two cells and those
  cells continues to divide over and over(cleavage)
  resulting in the development of an embryo.
• The embryo develops into a multi-cellular
  organism inside the female (in most mammals) or,
  outside (in an egg shell) in other animals.

21

• Draw the events from fertilization to development
  of an embryo (p. 32).

22

• Weird Fact In seahorses the female inserts her
  oviduct into the males brood pouch where the
  eggs are fertilized and develop.
• In a matter of speaking the male sea horse is
  pregnant!

23

• 2. Sexual Reproduction in Plants
• Sexual reproduction in plants also involves
  gametes.
• Male gametes and female gametes join during
  fertilization to produce a zygote and then an
  embryo.
• Most plants produce both male and female gametes,
  while some produce only one or the other.

24

• Pollen contains the male gametes and is found on
  the stamen.
• Ovules contain the female gametes and are found
  in the pistil.

25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28

• Pollination occurs when pollen is transferred
  from the anther of the stamen to the stigma of
  the pistil.
• Cross-pollination occurs when pollen from one
  plant is carried to the stigma of another plant
  by wind, water, animals or insects (bees or
  butterflies).
• Cross-fertilization occurs when a grain of the
  pollen forms a long tube which grows down the
  style into the ovary.
• The gametes unite to produce a zygote, which then
  develops into an embryo.

29

• This usually happens inside a seed which protects
  the embryo. The seed also provides food
  (cotyledon) for the embryo as it begins growing
  when conditions are suitable.
• Plants produced as a result of cross-fertilization
  are not identical to either parent plant, but
  will have a combination of characteristics from
  both parents.

30
(No Transcript)
31
(No Transcript)
32
Video Link Plant Reproduction
plant reproduction MonD Nye Flowers
33

• 3. Organisms that Reproduce both Sexually and
  Asexually
• Sponges are organisms that can produce both
  sexually and asexually. Most plants that produce
  seeds can also reproduce asexually (cuttings,
  runners).

34
Advantages and disadvantages of Asexual and
Sexual Reproduction

• Sexual Reproduction
• ADVANTAGES
• Greater genetic variation within a species
• Variation usually helps a species survive when
  the environment changes.
• DISADVANTAGES
• Takes a lot of energy
• Takes a lot of time
• Comparatively smaller populations are produced.

• Asexual Reproduction
• ADVANTAGES
• does not require any specialized cells
• only need one parent
• produce many offspring very quickly
• advantage where the environment doesn't change
  very much (ex. bacteria).
• DISADVANTAGES
• little genetic variation
• less adaptability to a new or changing environment

35

• Define hermaphrodite (p.32)
• Give 2 examples.

36

• Do Check and Reflect p.36 1-6, and 11
• Do Section Review p.37 1,3,5,9,10

37

• Do Flower Lab p.34