Topic 2: Multicellular Organisms Flashcards
What is reproduction?
Reproduction is the production of new members of a species
Sexual reproduction
2 parents and involves sex cells
Asexual reproduction
1 parent and involves no sex cells
Most animal reproduce…
Sexually
Gametes
Another word for sex cells
Male gamete
Sperm
Female gamete
Egg
Fertilisation
The fusion of the nuclei of two haploid gametes to produce a diploid zygote.
Zygote
A fertilised egg
Where does fertilisation take place?
In the oviduct
Where does the fertilised egg implant?
In the wall of the uterus
Oviduct
This is where fertilisation occurs. It is tube that allows the passage of eggs from an ovary
Vagina
Provides a passage for blood from the uterus during period. Recives the penis during sex and holds the sperm until the pass into the uterus.
Uterus
Where the fetus develops and grows
Ovary
Produces and stores eggs and creates hormones
Cervix
Allows fluids to flow in and out of the uterus
Uretha
Empties urine from the bladder
Penis
Male organ used for sex and urination
Sperm tube
Moves sperm away from the testicle
Testis
Male organ that produces sperm and hormones
Scrotum
Bag of skin that holds and protects testicles
Diploid
2 sets of chromosomes (23 pairs)
Haploid
1 set of chromosomes (23 single chromosomes)
Number of chromosomes in sperm cell
23 chromosomes (haploid)
Number of chromosomes in egg cell
23 chromosomes (haploid)
Number of chromosomes in a embryo
46 chromosomes (diploid)
What happens to the set of chromosomes when a sperm cell is fertilised with an egg cell?
It will double
Mitosis
A type of cell division. It involves a cell dividing to produce an identical daughter cell.
Why is mitosis essential?
It is essential for growth and repair and also keeps the chromosome complement.
Step 1 of Mitosis (interphase)
Cell is ready to divide and DNA is copied
Step 2 of Mitosis (prophase)
Chromosomes condense and becomes visible and the nucleus breaks down.
Step 3 of Mitosis (metaphase)
Chromosomes line up at the equator of the cell with spindle fibres
Step 4 of Mitosis (anaphase)
Chromosomes (now chromatids) are pulled apart to opposite poles of the cell.
Step 5 of Mitosis (telephase)
The membrane around the nucleus forms around each set of chromosomes
Step 6 of Mitosis (cytokinesis)
The cytoplasm divides, forming two genetically identical daughter cells
Stem cell
An unspecialised cell (doesn’t yet have a special job to do)
Embryonic stem cells
Found in embryos. Unspecialised cells with the ability to differenate into any type of cell in the human body
Adult stem cells
Different to embryonic stem cells as they are more limited and can only form cells that belong to their tissue type.
What can stem cells do while remaining unspecialised?
They can divide and multiply while staying unspecialised
Why are stem cells used in research?
They are involved in the body’s growth and repair and could be used to treat diseases.
Explain the controversy of using stem cells in research.
Embryonic stem cells are more efficent as they could be any type of cell but to obtain a embryonic stem cell, you must destroy the embryo and many people think that is the same as taking a human life.
Self-renewal
Copying of a stem cell
Differentiation
The making of different type of cells
What is the fetus surrounded by?
Amniotic fluid
What is the umbiolical cord attached to?
The placenta
How is the placenta essential to the fetus growth?
It allows food and oxygen to pass from the mother to the embryo. It also removes carbon dioxide and waste from the embryo’s blood and passes it to the mother where it can be filitered out.
Stage 1 of fetus development
Fertilisation: The nucleus of the sperm and egg fuse together
Stage 2 of fetus development
Embryo formation: The cells of the zygote begin to divide
Stage 3 of fetus development
Implantation: Embryo becomes attached to the wall of uterus
Stage 4 of fetus development
Placenta development: Some of the cells in the embryo become a placenta
Stage 5 of fetus development
1st trimester: Embryo develops into a foetus and vital organs are made.
Stage 6 of fetus development
2nd trimester: Rapid growth and continued development of organs, skin, hair and more
Stage 7 of fetus development
3rd trimester: Foetus is now fully grown but continues to grow until birth
Stage 8 of fetus development
Birth: The cervix opens and strong muscle contractions push the baby out of the uterus.
What does asexual reproduction NOT involve?
Fertilisation
Clone
An individual who is genetically identical to its parent
Advantage of sexual reproduction
Variation in the population which means increased chance of survival
Disadvantage of sexual reproduction
Slow process, takes time to find a mate
Advantage of asexual reproduction
Fast process, only one parent so no time is lost in trying to find a mate
Disadvantage of asexual reproduction
No variation and can be a problem if the enviroment changes
What does variation allow?
It allows some members of the population to survive and adapt to changing enviromental conditions
Parthenogenesis
A form of asexual reproduction in which an egg can develop into an embryo without being fertilised by a sperm
Parthenogenesis greek meaning
Virgin birth
Where in a flower does pollen grains land?
Stigma
Where do sex cells in a flower travel to?
The ovary
Male sex organ in a flower
Stamen (anther)
Male sex cells in a flower are contained in…
pollen grains
Female gamete of a flower
Ovules
Male gamete of a flower
Pollen
Sepal
Protects the unopened flower bud
Petal
May be brightly coloured to attract insects
Stamen
Male reproductive organ in a flower, consists of two parts: filament and anther.
Anther
Produces male gametes (pollen grains)
Stigma
Top of the female part which collects pollen
Ovary
Bottom of the female part which produces the female gametes (ovules)
Nectary
May be present to produce sugary nectar to attract insects
Female sex organ in a flower
Ovary
Where does fertilisation in a flower occur?
In the ovary
How do plants increase their number?
By producing seeds
Vegetative Propgation
When plants make copies of themselves without making seeds
Clones
When a plant is genetically identical to their parent plant
Natural Propagation
When the plant will make a copies of itself
Artificial Propagation
Menas that part of a plant is cut off from its parent and is treated so that it grows into a new plant
Rooting powder
Used before planting when the cut stem does not develop roots easily
Propgators
A piece of equipment that provides a humid atmosphere
The 5 methods of natural vegetative propgation
Bulbs, tubers, offsets, plantlets, runners
Example of a bulb
Onion
Example of a runner
Strawberry
Example of a offset
Aloe vera
Example of a plantlet
Kalanchoe
Example of a tuber
Potato
What do plants produced asexually lack?
Variation
What are 2 methods used in artificial propgation
Cutting and grafting
Variation
Difference between in genes and DNA in the population
Lifecycle
A diagram to represent the stages of development in an organism’s lifetime
Internal fertilisation
Fertilisation that occurs inside the organism
External fertilisation
Fertilisation that occurs outside the organism
An example of internal fertilisation
Mammals as it occurs inside the fallopian tube
An example of external fertilisation
Fish/frogs in the liquid medium they live in
Nature
Genes we inherit from our parents
Nurture
The enviromental factors our physical appearance
What is our appearance due to?
Nature AND nurture
Seed germination
An example of polygenic inheritance
Polygenic inheritence
Mixture of different genes from its parent
What makes successful seed germination?
Genes the embryo inherits and water, oxygen and correct temperature
Continous variation
Ranges from a minimum to a maximum value between two extremes. Controlled by many genes (polygenic inheritance)
Discrete variation
Can be seperated into distinct groups according to their trait. Controlled by different forms of the same gene (single gene inheritance)
Examples of discrete variation
Freckles
Blood group
Flower colour
(these all stay the same)
Examples of continous variation
Height
Hand span
Weight
(these keep growing)
Chromosomes
Long thread like structures found in the nucleus. Carries genetic information
Genotype
The genes an organism inherits
Phenotype
The physical features of an individual - determined by their genes
Alleles
Different forms of the same gene. One from the mother and one from the father
Dominant
The form of gene (allele) that hides a recessive form of a gene if present
Recessive
The form of gene (allele) that is hidden by a dominant form of a gene
Homozygous/true breeding
An individual who has two alleles that are identical for a particular trait (BB or bb)
Hetrozygous/hybrid
An individual who has two alleles that are different for a particular trait (Bb)
What do we use to represent alleles?
Letters
The larger letter will always be…
the dominant gene
The smaller letter will always be…
the recessive gene
Punett square
A method that is used to calculate the pssibility of having a specific trait
How do we find the F2 generation?
Cross 2 members from the F1 generation
What will a F2 generation from a true breeding cross reveal?
Both dominant and recessive traits from the parent generation
Why is it essential for new cells to be genetically identical?
So they have the genetic information to function
