asexual and sexual reproduction: 2.0 Flashcards
Non-heritable characteristics
Characteristics that are not passed down through generations.
Ex. A person who learned to play the piano will not have offspring born with that ability.
Heritable characteristics
Characteristics that are passed from generation to generation
Ex. Eye colour, hair type, skin colour
Discrete variation
The differences in characteristics that have a defined form
Ex. Cat either has blue eyes or does not have blue eyes
Continuous variation
The differences in characteristics that have a range of forms.
Ex. Height of adults can range in different sizes
Variation resulting in its environment
Variations in individual organisms result from the interactions they have with their environment. The variations created are not heritable.
Ex. A plant in a sunny window will thrive in colour whereas one in a dim closet will be spindly and dull in colour
Changes that affect animals
Death from old age, predation, disease, injury or sudden in environment changes such as earthquakes or temp drops and rises
What helps species survive those changes
Adaptation and reproduction. When an organism matures it can reproduce with one another to survive and thrive through their variations.
Types of reproduction
Sexual and asexual
Asexual reproduction
Involves one parent
Offspring are identical to parent
Some forms of this reproduction are binary fission, Spore reproduction, budding and vegitative reproduction
Asexual reproduction occurs most among…
Plants such as the spider plants who make runners and micro-organisms such as fungi and bacteria. May also occur in more primitive animals as the hydra
Binary fission
These animals simply split their cells in two by a form of cell division called cleavage. The cytoplasm separated to surround each new nucleus. The result is two identical individuals
The parent no longer exists as a single unit but has become two daughter cells
Only single-called organisms such as bacteria and other protests such as amoeba reproduce this way.
Budding
Involves the development on the body surface of the parent by creating a smaller version of itself which eventually detached and becomes a new individual that is identical to its parent
Yeast, coral and hydra reproduce this way
Spore reproduction
Spores are similar to seeds, but produced by division of cells of that parent, not by the Union of two cells.
Fungi, green algae, some moulds and non-flowering plants such as ferns reproduce by producing spores
Vegitative reproduction
The reproduction of a plant that does not involve the formation of a seed. Plants such as strawberries or spider plants grow runners that produce new plants. Other forms of vegitative reproduction includes tubers such as potatoes or the roots of an aspen tree which produce a form of root called a sucker
Sexual reproduction
Most species of animals and plants reproduce sexually. Female and male parents are usually involved in sexual reproduction.
Gametes
Each parent produces special sex cells called gametes. Gametes contain half chromosomes that every other adult cell in the body has
Female gametes
Known as egg cells
Male gametes
Known as sperm cells
Fertilization in animals
Occurs when the sperm cell and the eggs cell combine.
When the nuclei of two gametes fuse together during fertilization, the resulting cell or zygote contains the full number of cromosons
A gamete also contains 2 sets of hereditary information, one from each parent
Zygote
Divides into two cells. Each of these cells divided into two more cells. The process continues and is known as cleavage. Repeated cell division results in a new multicellular life form known as an embryo
Hermaphrodites
Animals such as earthworms and snails , have both ovaries and testes in each individual. Most hermaphrodites cross fertilize with one another of their species. In most animals the sex organs are separate I’m different individuals
Sexual reproduction in plants
This reproduction in plants requires the joining of male and female gametes to produce a zygote and than made into an embryo
Most plants produce both genders of gametes
Pollen in plants
Contains make gametes of a plant and the pollen is found on the stamen
Stamen
Make part of plant
Ovules in plants
Contain female gametes of a plant and are found in the pistil
Pistil
Female part of the plant
Pollination
Occurs when the pollen is transferred from the anther of the stamen to the stigma of the pistil
Fertilization
Occurs when the make and female gametes unite
Cross-pollination
Occurs when the pollen of one plant is carried to the stigma of another by wind, water or animals such as bees
Cross-fertilization
Occurs when a grain of pollen from one plant lands on the pistil of another and produces a long tube that grows down the style and into the ovaries that contain the ovules
What contains sex cells
Pollen grains and ovules
Embryos inside seeds
In most plants the embryo is produces inside a seed
The seed protects the embryo and stored food for the embryo when it starts to grow
Advantages of asexual reproduction
Doesn’t refugee any specialized cells to bring the gametes together making the process of fertilization quicker
They can make identical copies of themselves, reproducing quickly
Advantages of sexual reproduction
There is lots of variation in the species created sexually from mixed genes, this allows the species to adapt more to environmental change
Disadvantages of asexual reproduction
Little variation in a species could wipe out an entire population of the conditions are bad for their species
Disadvantages of sexual reproduction
Requires a lot of energy and method to bring the two cells together in fertilization
Limited number of offspring produced
Stamen (male part) contains….
Anther: holds pollen grains with male gametes in them
Filament: holds up the anther
Pistil (female part) contains…
Stigma: collects pollen grains containing male gametes
Style: passage for the tube created by the pollen down to the ovaries
Ovary: where the ovules are held to create fertilization and the production of a new embryo
Organisms that reproduce bathe sexually and asexually
Sponges can reproduce both ways and most plants the produce seeds can also reproduce asexually (cuttings, runners) depending on the environmental conditions the amount of energy varies, enabling the plant to control its population
