题干

端粒存在于真核生物染色体的末端,是由DNA序列及其相关的蛋白质所组成的复合体.端粒酶是一种逆转录酶,由蛋白质和RNA构成.由此可知,属于核膜、端粒和端粒酶共同点的是(    )

A:都存在于所有生物细胞中

B:都含有C、H、O、N、P等化学元素

C: 都与遗传信息的传递无关

D: 都含有遗传物质

上一题 下一题 0.0难度 选择题 更新时间:2014-01-07 03:31:41

答案(点此获取答案解析)

B

同类题2

It's important to teach children to create strong passwords(密码),and to remind them that passwords mustn't be shared with anyone, not even best friends.

A strong password is a word that is as difficult as possible to guess because it looks like a set of random characters (随机的字符).

It's wise to use the whole keyboard to mix a password with letters, numbers and symbols. A password of 14 characters or more may be much safer.

The following tips will tell you how to create a strong and safe password:

Tip 1: Think of a sentence that is easy to remember, but difficult to guess. For example: “ My son Peter is five years old and my daughter Tina is one year old.”The whole sentence is so long that it can't be a password, so what you can do is to use the first letter of each word to make a new password that seems to be meaningless. That is “mspifyoamdtioyo”.

Tip 2: Make the password more difficult to guess by mixing big and small letters. One way to do this is to use big and small letters one after another. In this way this new password will be “MsPiFyOaMdTiOyO”.

Tip 3: Still using the sentence above, you can also add numers that are meaningful to you. As a result, the new password will be “Mspi5yOaMdTi1yO”.

Tip 4: Add punctuation(标点符号)and symbols to make the password much stronger. You may use symbols, numbers and punctuation to replace some letters which look similar. For example: “MsPi3y0@MdTi!y0”.(o=0, a=@, 1=!)

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