In a plant in which fuzzy leaves (F) are dominant over smooth leaves (f), which of the following crosses will produce only offspring with smooth leaves?
FF x FF
Ff x Ff
ff x ff
Ff x ff.
The Correct Answer is C
In this cross, both parents are homozygous recessive for the smooth leaf trait (ff).
This means that all of their offspring will inherit two copies of the recessive allele (f) and will therefore have smooth leaves.
Choice A. FF x FF is not correct because both parents are homozygous dominant for the fuzzy leaf trait (FF) and all of their offspring will inherit two copies of the dominant allele (F) and will therefore have fuzzy leaves.
Choice B. Ff x Ff is not correct because both parents are heterozygous for the leaf trait (Ff) and their offspring can inherit either one dominant allele (F) or one recessive allele (f) from each parent, resulting in a 3:1 ratio of fuzzy to smooth leaves.
Choice D. Ff x ff is not correct because one parent is heterozygous for the leaf trait (Ff) while the other is homozygous recessive (ff), resulting in a 1:1 ratio of fuzzy to smooth leaves in their offspring.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Melanin is a pigment produced by cells called melanocytes in the skin.
It protects the skin from ultraviolet (UV) radiation by absorbing and dissipating over 99.9% of absorbed UV radiation.
This helps to prevent DNA damage and other adverse effects of UV radiation on the skin.
Choice B. Perspiration is not correct because it is a fluid produced by sweat glands in the skin that helps to regulate body temperature, but it does not protect the skin from UV radiation.
Choice C. Sebum is not correct because it is an oily substance produced by sebaceous glands in the skin that helps to lubricate and protect the skin, but it does not protect the skin from UV radiation.
Choice D. Keratin is not correct because it is a fibrous protein that provides strength and durability to the skin, hair and nails, but it does not protect the skin from UV radiation.
Correct Answer is A
Explanation
Cytokines are chemicals released by one type of immune cell to directly activate another type of immune cell.
They are small proteins that act as messengers between cells and play a key role in regulating the immune response.
Choice B. Lysozymes is not the correct answer because lysozymes are enzymes that break down bacterial cell walls and do not directly activate other immune cells.
Choice C. Perforin is not the correct answer because perforin is a protein that forms pores in the membranes of target cells and does not directly activate other immune cells.
Choice D. Granzymes is not the correct answer because granzymes are enzymes that enter target cells and trigger apoptosis (cell death) and do not directly activate other immune cells.
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