Which of the following statements about maternal-effect genes is not correct?
A. Maternal-effect genes are expressed by
the mother but affect the phenotype of the
offspring.
B. The composition of RNA and proteins in an
oocyte is not uniform across the cell.
C. bicoid and nanos mRNA and protein in
Drosophila oocytes are localized either in the
anterior (bicoid) or posterior (nanos) of the
egg.
D. The anterior-posterior axis set up by
gradients of Bicoid and Nanos proteins is
reinforced by gradients of two transcription
regulators called Caudal and Hunchback.
E. The caudal and hunchback mRNAs are
transcribed in the egg and then transported
back to regulate the mother's genome.
E
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An example of mechanical isolation would be
a. flowers that bloom months apart. b. two organisms that are pollinated by different insects. c. two organisms that have different habitats. d. two organisms that have incompatible gametes. e. two organisms that have different mating rituals.
Answer the following statements true (T) or false (F)
1.Weak muscular contraction could be due to either poor binding of actin and myosin or to insufficient calcium available to stimulate contraction. 2.Bones can provide calcium to the rest of the body if it is needed. 3.Bones have blood vessels attached to their surfaces but not penetrating them. 4.The long bones of the human body begin as cartilaginous structures in embryos. 5.The long bones of the human body elongate during development via growth plates at their ends.
Many zooplankton migrate to the surface to graze on phytoplankton during the day and retreat to deeper water during the night
Indicate whether the statement is true or false
One way to detect the growth of a virus in culture is to observe the degeneration and lysis of infected cells in the monolayer of cells. These areas show up as clear, well-defined patches in the cell sheet called
A) colonies. B) plaques. C) turbidity. D) cottony patches.