37 Questions
Which type of eggs have yolk that is localized to one half of the egg, known as the vegetal hemisphere?
Mesolecithal eggs
Which class of eggs has yolk concentrated in the centre with a peripheral layer of yolk free periplasm?
Centrolecithal eggs
Which type of eggs have even distribution of little yolk throughout the cytoplasm?
Isolecithal eggs
Which type of eggs are described as having moderate to large amounts of yolk that fill the cytoplasm except for a small area near the animal pole?
Telolecithal eggs
Where are most amphibian eggs, such as Xenopus laevis, classified in terms of yolk distribution?
Mesolecithal
Which class of eggs belongs to animals like zebrafish and chick?
Telolecithal
What was the reason chicken eggs were chosen for the first microscopic study of embryonic development according to the text?
Large size and accessibility at most developmental stages
Which animal model was used for more than 50 years before the South African clawed frog Xenopus laevis became prominent according to the text?
Multiple species of salamander
What makes the South African clawed frog Xenopus laevis an attractive model for developmental studies?
Ability to be induced to lay eggs all year by injecting human pregnancy hormone
Why are chicken eggs considered excellent for micromanipulation studies according to the text?
Large size and embryo accessibility
What significance does the chick genome sequencing have according to the text?
Shows significant similarity with mammalian genomes
What is a unique advantage of using chicken eggs for propagating viruses, as mentioned in the text?
Eggs are large and easy to obtain
Why did Marcello Malpighi choose chicken embryos for the first microscopic study of embryonic development?
'The large size of chicken embryos allowed better observation
What did Sir John Gurdon use Xenopus laevis for in his pioneering studies?
Single cell nuclear transfer
Why is Xenopus tropicalis preferred over Xenopus laevis for genetic studies?
Shorter life cycle
What significant similarity do the genomes of Xenopus laevis and Xenopus tropicalis share with mammals?
Protein coding sequences
Why was Zebrafish (Danio rerio) chosen as a model organism for large scale genetic screens?
Large scale genetic screens capabilities
Which Nobel laureate initiated a systematic attempt to identify all the genes involved in zebrafish development?
Christiane Nüsslein-Volhard
What is one factor that makes Xenopus laevis unsuitable for classical genetics?
Long life cycle
Which species has largely tetraploid genome among Xenopus laevis and Xenopus tropicalis?
Xenopus laevis
What did Sir John Gurdon's studies on mature cells reprogramming lead to?
Discovery of animal cloning techniques
What is the function of the zona pellucida in preventing fertilization by sperm of different species?
Serve as a barrier that only allows species-specific sperm to bind.
What protein is the sperm receptor of the mouse egg?
ZP3
What event induces the acrosome reaction in sperm?
Release of enzymes from the acrosome.
What is the purpose of the cortical reaction in fertilization?
To modify the sperm receptor ZP3 so sperm can no longer bind or penetrate.
Why is it important for the mammalian egg to prevent polyspermy?
It prevents faulty segregation of chromosomes during mitosis.
What is released during the cortical reaction that helps prevent polyspermy?
Contents of cortical granules
Which cellular event allows sperm to penetrate through the zona pellucida?
Release of acrosomal enzymes
What would happen if polyspermy occurs during fertilization in mammals?
Faulty segregation of chromosomes during mitosis would occur.
What is the main function of Chorionic Gonadotrophin as mentioned in the text?
Serve as a pregnancy test inducing egg laying in Xenopus leavis
What is the primary function of nurse cells in relation to oocytes?
Retain connections with oocytes to transport RNA and protein
How do ostrich eggs differ from human eggs?
Ostrich eggs contain yolk proteins while human eggs do not
What happens to the number of oocytes in the fetal ovary from the fetal stage to puberty in humans?
Decreases from 6 million to about 40,000
What is the significance of vitellogenin genes detected in the human genome?
They are mutagenised pseudogenes with unknown function
Which organism was introduced into UK laboratories in the 1930’s and used as a pregnancy test?
Xenopus leavis
What is the primary source of synthesis for yolk proteins in vertebrates?
Liver
Why are some insect sperm longer than the egg itself?
To compensate for the smaller volume compared to egg size
Learn about the early studies on embryonic development through the observation of chicken embryos by Aristotle and Marcello Malpighi. Discover why chicken eggs were chosen for these studies and their significance in the field of biology.
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