问题 单项选择题

把数条5cm长的马铃薯条分别浸在蒸馏水和不同浓度的蔗糖溶液中,每隔一段时间测量马铃薯条的长度。如图显示马铃薯条在不同浓度溶液中长度改变的百分率。下列相关叙述错误的是()

A.马铃薯条通过渗透吸(失)水改变其长度

B.在0.10mol/L蔗糖溶液中马铃薯细胞质壁分离

C.马铃薯细胞细胞液浓度相当于0.30mol/L的蔗糖溶液

D.在0.40mol/L蔗糖溶液中马铃薯细胞失水皱缩

答案

参考答案:B

解析:试题分析:据图分析,马铃薯条浸在0.30M的蔗糖溶液中其长度基本不变,说明马铃薯细胞液浓度相当于0.30M的蔗糖溶液,C正确;浸在低于0.30M的蔗糖溶液中,马铃薯细胞通过渗透作用吸水膨胀,其长度增加,B错误;浸在高于0.30M的蔗糖溶液中,马铃薯细胞通过渗透作用失水皱缩发生质壁分离,其长度缩短,AD正确。考点:本题考查细胞渗透作用的实验,意在考查考生能理解所学知识的要点,把握知识间的内在联系,结合图形分析实验结果的能力。

单项选择题
单项选择题

Public Key Infrastructure (PKI) service providers offer organizations fully integrated PKI-managed services designed to secure Intranet, Extranet, Virtual Private Network (VPN), and e-commerce applications. PKI solutions can enable a number of security services, including p authentication and non-repudiation of transactions.
eToken enables the users of PKI systems to generate and store (101) and digital certificates inside the token, creating a secure environment and allowing full portability and maximum ease of use. eToken Pro can also perform sensitive on-chip (102) operations, ensuring that users’ keys axe never exposed to the PC environment, eToken eliminates the need to store (103) and keys on a hard disk or browser file, or to transmit them across the Internet/Extranet; assuring peace-of-mind and confidence during online communications.
A digital signature is created using the private key of an individual to ensure the Validity of his request. This technology can be used to guarantee (104) of various transactions. The strength of either the authentication level or the digital signature relies on the level of protection offered to the private key. eToken Pro offers the maximum level of security, since it enables the use of the private key for signing and authenticating inside the eToken.
The most secure use of authentication involves enclosing at least one certificate with every signed message. The message (105) verifies the certificate using the CA’s public key. If the sender’s public key is legitimate, the recipient verifies the message’s signature. Digital signatures created with a private key are verified with the digital certificate containing the public key.

A.private keys

B.public keys

C.authentication codes

D.message digests