Pollen tube growth is one of the most fascinating—and essential—phenomena in the life cycle of flowering plants. After a compatible interaction between pollen grains and the stigma surface, the pollen germinates and forms the pollen tube, which grows through the stigma, style, and transmitting tract to deliver the sperm cells to the ovule."
2) Although pollens of many species germinate in simple aqueous media, stigmas do not provide satisfactory sites for the germination of most foreign pollen... Stigmas not only provide the proper conditions for the germination of pollen from their particular species, they actively inhibit the germination of pollen of many unrelated species.
During DNA replication, the hydrogen bonds must be broken between the complementary nitrogenous bases in the DNA double helix
Answer:
The elements in increasing order of atomic radius: oxygen, carbon, aluminum, potassium
Explanation:
The distance from the center of the nucleus to the outermost shell of the electron is known as the atomic radius of an element. The atomic radius decreases rightward along each period (row) of the table due to the increase in effective nuclear charge (the charge of the nucleus equal to the number of protons). Across a period, electrons are added to the same energy level and the increasing number of protons causes the nucleus to exert more pull on these electrons, which makes the atomic radius smaller. Atomic radius increases down each group (column) of the periodic table because of the addition of electrons to higher energy levels, which are further away from the nucleus and the pull of nucleus weakens. Another reason for the increase in atomic radius is the electron shielding effect, which is the reduction of the attractive force between a nucleus and its outer electrons due to the blocking effect of inner electrons
While moving from left to right in the second period, c
arbon comes before oxygen and so oxygen will have a smaller atomic radius than carbon. While moving down the periodic table, al
uminum comes before potassium even if they are not in the same period. So aluminum
's atomic radius will be smaller than that of potassium but bigger than that of carbon and oxygen.
.
Answer:
1: I believe there are 8 (not sure but it’s no more than 8)
2: Sparrow hawk
Why? The sparrow hawk is getting its energy later in the web meaning that most of the energy has been used by other organisms
<span>Protein channels are needed to transport substances because it accelerates the transport process. Very few substances enter or leave cells without being attached to a transport protein. Different types of substances require different types of proteins to transport them. Protein channels transport water or ions downwards and ATP-powered pumps transport molecules or ions upwards. ATP generates energy to transport the molecules upwards. Gravity is used to transport the water molecules downwards. So, in a nutshell, if substances need to be transported from the top of the body downward, the force of gravity is used to transport the substances down. If substances need to be transported upwards, ATP, a coenzyme, is used to generate energy to transport the substance upwards</span>
