Adichotomous key is a key that can be used to identify a plant or animal in which each stage presents descriptions of two distinguishing characteristics, with a direction to another stage in the key, until the species is identified. mr. miller has assigned his science class the task of making a dichotomous key. the students must classify a chart of birds. which characteristic difference visible in the chart would be the best start for the dichotomous key?

You haven't provided the chart of birds nor a short description of it, but I can give you a general guide dealing with the use of a Dichotomous Key.

As you mentioned, a Dichotomous Key is a tool that allows the identification of organisms or objects, based on their morphological characteristics. For birds, there are some important features that can be useful to classify them into groups: size, beak shape, eyes, feet shape, feathers, tail form, primary colours, etc.

One of the first steps for starting a bird dichotomous key could be identify the birds location, but if you don't have this infomation, then classify them by size, going from very small to very large. If you don't have the size information, you can begin by classifying them by shape (pigeon-like, duck-like, owl-like, etc.). Other basic and useful way of classifying birds in a Dichotmous key is by beak shape (cone, needle, curved, etc.).

Explanation:

The best way to start a Dichotomous Key is going from general characteristics to more detailed ones. That's the reason why location could be an interesting first step, taking in account that bird's location is very important. Their shape, size and beak are also general features that you can notice just by looking at a bird chart, and could be a good first step to classify them into groups.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.