Regents Living Environment Test Preparation Practice

    Sexual Reproduction

    Base your answers to questions 1 on the information below and on your knowledge of biology.

    Female mosquitoes spread diseases when they bite humans to obtain blood. It is only the females that do the biting. Research is being conducted to alter the DNA of male mosquitoes. These altered males could then mate with normal female mosquitoes. All of the resulting female offspring would have wing defects that prevent them from flying.


    Base your answers to questions 16 on the passage below and on your knowledge of biology. Biologists have been studying the genes present in newborn twins.

    Twins Don’t Share Everything

    …Chemicals called epigenetic markers can be attached to those [inherited] genes, like flags or balloons hanging off the sides of the DNA ladder. These don’t just change the look of the genes. Like pieces of tape stuck over a light switch, these markers can force a gene to remain turned on or off. The type of marker scientists studied in the twins generally sticks the switch in the off position so that some proteins don’t get made. And that means the proteins’ jobs won’t get done.

    Every time a cell divides, new epigenetic markers may form. Foods, pollutants, and stress may all contribute to the development of new markers. So throughout our lives we tend to accumulate more and more. But a few are there from the day we’re born.

    …His [Jeffrey Craig’s] team found that newborn twins have markers attached to different genes from the very start. It’s true in identical twins, which come from the same fertilized egg. It’s also true in fraternal twins, which come from different fertilized eggs. However, fraternal twins had more such differences than identical twins did.

    Source: Science News for Students; July 31, 2012


    Base your answers to questions 17 on the information below and on your knowledge of biology.

    The testes of a human male produce gametes. The process that produces these gametes differs from the process that produces new skin cells in the same individual.


    Base your answers to questions 18 on the illustration and passage below and on your knowledge of biology.

    genetics and biotechnology, heredity affected due to changes in DNA fig: lenv82019-examw_g23.png

    A few breeds of cat have no tails. Manx cats have extremely short tails and may even appear to have no tail at all. Manx cats were first discovered several hundred years ago.

    Scientists have determined that a certain mutation in a group of genes (called T-box genes) interferes with the development of the spine in the cat embryo. Mutations in these T-box genes can cause abnormalities in the number, shape, and/or size of bones in the spines of Manx cats, which results in smaller spines and shorter tails.

    If a Manx cat inherits one copy of the mutated T-box gene and one copy of the normal gene, it will have a very short tail or no tail at all.

    If the cat embryo inherits two copies of these mutated genes, it will stop developing and die. Therefore, all surviving Manx cats have only one copy of the mutated gene.