In most male animals, the penis or other copulatory organ achieves erection by
A. artery dilation or hemolymph pressure.
B. bones or exoskeleton interlocking.
C. muscle contraction.
D. testicular pressure.
Answer: A
You might also like to view...
When the DNA sequence of the gene that codes for the peptide hormone insulin is compared in two mammals (e.g., humans and rats), most of the sequence differences are silent mutations
These far outnumber sequence differences that result in amino acid substitutions. Why might this be? A. Mutations are random with respect to an organism's needs. B. Amino acid substitutions often result in proteins that have lost or compromised function, and so are selected against. C. A DNA sequence is more likely to mutate if the change does not alter the amino acid sequence. D. Most amino acid substitutions result in a beneficial phenotype that improves fitness and results in a greater number of offspring. E. Silent mutations occur in noncoding DNA sequences.
An example of an invertebrate chordate belongs in the subphylum:
a. Vertebrata. b. Urochordata. c. Chelicerata. d. Crustacea. e. Pycnogonida.
Vegetative reproduction is rare in nature
Indicate whether the statement is true or false.
The ____ system is responsible for filtering wastes from the blood
a. respiratory b. urinary c. digestive d. endocrine e. circulatory