阅读材料，回答问题。

藏族由于“其腥肉之食，非茶不消；青稞之热，非茶不解”。而将茶作为“一日不可或缺”的生存必需品。但藏族所居的青藏高原地区，素不产茶。为了将川、滇的茶叶运入藏区，同时将内地急需、供不应求的藏区土特产如：骡马、药材等输入祖国内地；一条条以茶叶贸易为主的交通线——“茶马古道”在藏汉民族商贩、背佚、驮队、马帮劈荆斩棘下，被开辟出来。历史上的茶马古道并不只一条，它是以川藏道、滇藏道与青藏道（甘青道）三条大道为主线，辅以众多的支线、附线，构成的一个庞大的交通网络。地跨川、滇、青、藏四区，外延达南亚、西亚、中亚和东南亚各国。茶马古道源于古代西南边疆的茶马互市，唐朝中后期兴盛，宋、元、明、清持续发展，直到云南的公路和铁路修筑以后，茶马古道才完成了它的历史任务。

从1951年起，中国人民解放军和藏汉筑路工人经过艰苦奋斗，先后建成了川藏、滇藏、青藏等四通八达的公路网，加强了西藏同祖国各地区城乡之间的联系；2006年7月，由青海省西宁市至西藏拉萨市穿越世界屋脊的青藏铁路全线通车，为西藏经济社会发展带来了历史性机遇。—— 纪录片《茶马古道》

结合材料分析茶马古道的文化价值。

如图是两种不同细胞模式图，请据图回答下列问题：

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    The day finally came，when I had to leave the warm home where I'd grown up.I ran to the back yard，as tears came up from my heart.Suddenly I1a hand rest on my shoulder.I looked up to2mygrandfather.“It isn't3，isit，Billy？”he said softly.

    Gently4myhand in his，we walked，hand in hand，tothe front yard，5a hugered rose­bush sat alone.

    “What do you see here，Billy？” he asked.I looked at the flowers，not knowing6to say，and then answered，“I see something soft and7，grandpa.”

    He pulled me8.“It isn't just the roses that are beautiful，Billy.It's that special place in your heart that makes them so.”“Billy，I9these roses when my first son was born.It was my10of saying 'thank you' to God.I11to watch him pick roses for his mother. Then, as a young man of only 20，a terrible war robbed him of his life.” Grandpa slowly stood up.“Never say good­bye，Billy. Never12to the sadness and the loneliness.Instead，I want you to remember the joy and the13when you first said hello to a friend.”

    A year later，my grandpa became very14.Then all members of the family were15back，and I returned to the old house. When it came to my16，I took his hand as17as  he had once taken mine.

    “Hello，grandpa，”I18.His eyes slowly opened and said，“Hello，my friend.” With a brief19he died. Suddenly，and truly.I knew what he had20about never saying good­bye—about refusing to give in to sadness.​

如图，基因组成是AA的芒果枝条①，嫁接到基因组成为aa的砧木②上，所结芒果的性状表现和基因组成分别为（　　）