Предмет: Биология, автор: domfedora2201

Пж помогите.Строение клубня и строение луковицы

Ответы

Автор ответа: ddoki
5

Ответ:

Строение клубня

Клубни отличаются от корневищ тем, что у них стебель короткий и толстый, а листья недоразвиты. Как и на всяком побеге, у них имеются почки и расположены они на верхушке и в пазухах недоразвитых листьев. Придаточные корни на клубнях не развиваются. Клубни у картофеля вырастают из подземных почек не сразу. Сначала из почки растёт длинный белый подземный побег — столон. Столон живёт меньше года. Верхушка со временем начинает утолщаться и превращается к осени в клубень.

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Строение луковицы

Семена растений обычно прорастают, попав в землю находятся на некоторой глубине. Самый первый побег, растущий из почки зародыша, должен пробиться сквозь почву. На этой подземной части стебля обычно вырастают первые придаточные корни. Они могут втягивать основание стебля в почву ещё глубже, чем оно было погружено первоначально. В отличие от корневищ и клубней, у луковиц хорошо развиты листья, а стебель очень короткий и плоский. Его называют «донцем».

На верхушке донца под прикрытием чешуй находится почка, из которой вырастает надземный побег. Из пазушных почек, расположенных ниже верхушечной, образуются новые «дочерние» луковицы. Из каждой дочерней луковицы — «детки» может вырасти новое растение.

Объяснение:


domfedora2201: Спс
NLHYTYT: ха
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нужен перевод текста. THE FIRST AMERICANS

At daybreak on the morning of Friday, August 3, 1492, an Italian adventurer named Christopher Columbus set sail from Spain to find a new way from Europe to Asia. His aim was to open up a shorter trade route between the two continents. In Asia, he intended to load his three small ships with silks, spices and gold, and sail back to Europe a rich man.

Columbus first sailed south to the Canary Islands. Then he turned west across the unknown waters of the mid-Atlantic Ocean. Ten weeks after leaving Spain, on the morning of October 12, he stepped ashore on the beach of a low sandy island. He named the island San Salvador - Holy Savior. Columbus believed that he had landed in the Indies, a group of islands close to the mainland of India. For this reason he called the friendly, brown-skinned people who greeted him "los Indios" - Indians.

In fact, Columbus was not near India. It was not the edge of Asia that he had reached, but islands off the shores of a new continent. Europeans would soon name the new continent America, but for many years they went on calling its inhabitants Indians. Only recently have these first Americans been described more accurately as "native Americans" or Amerindians.

There were many different groups of Amerindians. Those north of Mexico, in what is now the United States and Canada, were scattered across the grasslands and forests in separate groups called "tribes." These tribes followed very different ways of life. Some were hunters, some were farmers. Some were peaceful, others warlike. They spoke over three hundred separate languages, some of which were as different from one another as English is from Chinese.

Europeans called America "the New World." But it was not new to the Amerindians. Their ancestors had already been living there for maybe 50,000 years when Columbus stepped on to the beach in San Salvador.

We say "maybe" because nobody is completely sure. Scientists believe that the distant ancestors of the Amerindians came to America from Asia. This happened, they say, during the earth's last ice age, long before people began to make written records.

At that time a bridge of ice joined Asia to America across what is now the Bering Strait. Hunters from Siberia crossed this bridge into Alaska. From Alaska the hunters moved south and east across America, following herds of caribou and buffalo as the animals went from one feeding ground to the next. Maybe 12,000 years ago, descendants of these first Americans were crossing the isthmus of Panama into ...

The lifestyle of the people of North America's northwest coast was different again. They gathered nuts and berries from the forests, but their main food was fish, especially the salmon of the rivers and the ocean. Each spring hundreds of thousands of salmon swam in from the Pacific and fought their way up the fast-flowing rivers to spawn. A few months' work during this season provided the people of the Pacific coast with enough food to last a whole year.

This abundance of food gave the tribes of the Pacific coast time for feasting, for carving and for building. Tribes like the Haida lived in large houses built of wooden planks with elaborately carved gables and doorposts. The most important carvings were on totem poles. These were specially decorated tree trunks which some tribes placed in front of their houses, but which the Haida made part of the house itself. The carvings on the totem pole were a record of the history of the family that lived in the house.

The Amerindian peoples of North America developed widely varied ways of life. All suited the natural environments in which the tribes lived, and they lasted for many centuries. But the arrival of Europeans with their guns, their diseases and their hunger for land would eventually destroy them all.