Section 4 Reproduction National 5 Multicellular Organisms Learning
- Slides: 10
Section 4 – Reproduction National 5 - Multicellular Organisms
Learning Outcomes • By the end of this section I will be able to: • - identify the difference between asexual & sexual reproduction • - identify the sites of gamete production in animals • - identify the key structures of these sites • - explain what happens during fertilisation • - compare the methods of fertilisation in different animals
Re-Cap • 1) What are the two types of reproduction called? • 2) What are gametes? • 3) What do the terms haploid and diploid mean?
Site of gamete production - humans • In animals, the gametes are the sperm and the egg • The sperm are produced in the male testes • - sperm travel through the sperm duct into the penis • Egg cells are produced in the female ovaries • - process known as ovulation • The penis of the male deposits sperm • - inside the vagina of the female • The sperm them swim to the fallopian tube/oviduct to meet the egg • Here fertilisation occurs Penis Testes Oviduct
Fertilisation • When the sperm and egg cell nuclei fuse together • These haploid cells join to form a diploid cell • - this is called a zygote • This will then divide to form a ball of cells • - a blastocyst • This will then implant itself inside the wall of the uterus • It will then grow and develop – gestation period
Development of human embryo Uterus wall Placenta Amniotic sac Umbilical cord Amniotic fluid http: //www. on 101. co. uk/foetal. html Embryo/Foetus
The Placenta The placenta is where the blood of the mother and foetus are brought close together. A thin barrier separates the bloodstream of mother and baby. Oxygen and dissolved food diffuse into the baby’s bloodstream from the mother. Carbon dioxide and waste diffuse from the baby into the mother’s blood.
PLACENTA Mother’s blood going to placenta Mother’s blood leaving to placenta Blood to the embryo Blood From the embryo
Twins • Account for around 3% of all births • 2 possible types: • IDENTICAL (MONOZYGOTIC): • - after fertilisation, a zygote will sometimes split into two • - these will then develop separately into two different embryos • - these share a placenta and amniotic sac • - genetically identical • NON-IDENTICAL (DIZYGOTIC): • - when two eggs are released and fertilised by two sperm • - different placenta and amniotic sac • - genetically different
Asexual Reproduction • Doesn’t involve sex cells or fertilisation • All offspring are identical to their parent • Animals • Usually only occurs in micro-organisms • - yeast reproduce by budding • - bacteria/fungi can reproduce by fission
- What are unicellular and multicellular organisms
- Multicellular organisms images
- Multicellular simple definition
- Plant - multicellular eukaryote of the kingdom plantae
- What is a unicellular organism
- What is cell called
- Multicellular organisms
- Multicellular organisms
- Eudocot
- Organism
- How are unicellular and multicellular organisms alike