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