Four genes (A, B, C, D) are known to be located on the same chromosome. A series of crosses was completed to determine the recombination frequencies: A-B 50% A-C 18% A-D 31% B-C 39% B-D 50% C-D 49% Based on these numbers, what is the map distance between A and B

Explanation:

1. The largest possible map distance is 50, it represents that  two genes are found at opposite ends of a chromosome or are 50 cM apart from each other or they are found on different chromosomes .

2. Genes found at opposite ends of a chromosome behave as if they are on different chromosomes.

3. As given A-B 50%, means  that recombination frequency is 50%.

The recombination frequency(RF), 50% means that either two genes are located on different chromosomes inheriting independently or  when they are widely separated on the same chromosome with far distance.  

4. As  given here, four genes named A, B, C,  and D are known to be located on the same chromosome. so A-B are 50 cM or more  far  apart from each other.

1: most common garden plants prefer loam — soils with a balance of different-sized mineral particles (approximately 40% sand, 40% silt, and 20% clay) with ample organic matter and pore space. however, some plants grow better in sandy soils, while others are well-adapted to clay soils.

2: available water capacity is the maximum amount of plant available water a soil can provide. it is an indicator of a soil's ability to retain water and make it sufficiently available for plant use. available water capacity is the water held in soil between its field capacity and permanent wilting point.

3: it is the same for all living things (plants and animals). it also includes very tiny organisms that our eyes cannot see. they are known as microorganisms, and include viruses, bacteria and fungi.