Biology Test Preparation Practice

    Inheritance And Variation Of Traits

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    Base your answers to questions 2 on the diagram below and on your knowledge of biology. The diagram represents the human female reproductive system.

    reproduction and development, human female reproductive system fig: lenv12013-exam_g3.png

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    Base your answer to question 12-15 on the information below and on your knowledge of biology.

    Artificial Placenta

    It is estimated that every year more than 15 million babies are born too early. The lungs of these premature infants are often immature and easily damaged. Premature births happen for a variety of reasons—some known and some unknown. Those that are known include infections and conditions such as diabetes and high blood pressure. Scientists are researching what causes premature births, in an attempt to develop solutions to prevent them.

    Scientists are also working on the development of an artificial placenta. At the University of Michigan, five premature lambs were placed in artificial placentas and kept alive for weeks. During this time, each lamb’s blood was circulated through its artificial placenta.

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    Base your answer to question 16-18 on the information below and on your knowledge of biology.

    The Critical Role of the Placenta

    The proper functioning of the placenta is critical to the growth and development of a healthy fetus. For example, the placenta appears to act as a nutrient sensor. It regulates the amounts and types of nutrients that are transported from the mother to the fetus.

    Improper functioning of the placenta can alter the structure and function of specific cells and organ systems in the developing fetus, putting it at risk for health problems as an adult. For example, in some pregnancies, the placenta develops a resistance to blood flow. This resistance appears to force the heart of the fetus to work harder. This could result in an increased chance of the individual developing heart disease as an adult. A group of hormones known as glucocorticoids affects the development of all the tissues and organ systems. One of the things this group of hormones does is to alter cell function by changing the structure of cell membrane receptors.

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    Base your answers to questions 20 on the information below and on your knowledge of biology.

    Mitochondrial Replacement Therapy

    Mutations in mitochondrial DNA (mtDNA) are associated with some severe human diseases and are inherited through the cytoplasm in the egg cell. These diseases vary, but often affect organs and tissues with the highest energy requirements, including the brain, heart, muscle, pancreas, and kidney.

    Scientists have successfully used mitochondrial replacement therapy with monkeys. Scientists are considering using this technique to reduce the incidence of mitochondrial disease in children. The proposed treatment would involve removing the nucleus from an egg donated by a healthy woman and replacing it with an egg nucleus from a patient (mother) with mitochondrial disease. This would place the patient’s egg nucleus into the cytoplasm of the donor’s egg containing healthy mitochondria. The egg is then fertilized with the father’s sperm externally using in vitro fertilization (IVF) to produce a zygote. The zygote is cultured for a few days to produce an embryo.

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