Mammalian fertilization comprises sperm migration through the female reproductive tract, biochemical and morphological changes to sperm, and sperm-egg interaction in the oviduct. Recent gene knockout approaches in mice have revealed that many factors previously considered important for fertilization are largely dispensable, or if they are essential, they have an unexpected function. These results indicate that what has been observed in in vitro fertilization (IVF) differs significantly from what occurs during “physiological” fertilization. This Review focuses on the advantages of studying fertilization using gene-manipulated animals and highlights an emerging molecular mechanism of mammalian fertilization.
A large asteroid or comet impacted the earth.
Answer:
The correct answer is "Transgenics".
Explanation:
The missing options of this question are:
A. Artificial selection
B. Transgenics
C. Bioreaction
D. Recombination
The correct answer is option B. "Transgenics"
Transgenics is a term used to describe the artificial insertion of one or more DNA sequences to an organism that would normally not have it. In this example, the term transgenics applies to the cows that serve as hosts for the production of the spider silk. The process transgenics is what gives the name to terms such as "transgenic food", "transgenic plants" or "transgenic animals".
Answer No 1:
The set up of the punnet square is shown in the attached diagram. As the alleles assort independently hence the gametes formed will be OT,Ot,OT,Ot and OT,Ot,oT,ot. These will be the outcomes of the possible gametes formed. When these gametes are cross bred, the results are shown in the diagram attached.
Answer No 2:
The outcomes of each possible genotype are:
OOTT = 2/16
OOTt = 4/16
OOtt = 2/16
Oott = 2/16
OoTT = 2/16
OoTt = 4/16
Answer No 3:
The likelihood of each possible offspring phenotype is:
Orange petals with tall stem and orange petals with small stems present in ratio 12:4 i.e. 3:1.
Answer:
<u><em>PROPHASE</em></u>
Explanation:
The first stage in Meiosis I is prophase I. During this stage the DNA condenses into chromosomes. During prophase I, homologous chromosomes pair up and exchange sections of DNA. This is called recombination or crossing over
