Answer:
Interrupt the long winter nights with a brief period of light.
Explanation:
Long day plants, also called short night plants, flower when the dark period is equal or less than the critical period specific for the species. These plants normally flower in summers when nights are short and days are longer. Winters have a long dark period and do not support flowering in shirt night plants.
A continuous dark period is critical for flowering. A short night plant can flower in winters (having longer dark periods) if the dark period is interrupted by exposing the plant with a flash of light. To make short night plants, such as iris to flower in winters, the plant should be given short period of light after completion of critical dark period.
Answer:
A dog pants in the heat to control its body temperature. Panting is a mechanism of homeostasis that dogs use for regulation .
Answer:
d. K+ and Na+ both diffuse into the cell along their concentration gradients and drive the transport of glucose.
Explanation:
Na/K pump is a pump located on the plasma membrane which uses ATP to move 3 Na ions out the cell and brings in 2 K ions into the cell. It is an example of primary active transport. As a consequence,concentration of Na is higher outside the cell, while K concentration is higher inside the cell.
Glucose is transported in the cell against its gradient, together with Na ions (symport) which move down their concentration gradient.
This is an example of secondary active transport because it uses the energy from the primary active transport to move other substances such as glucose against their own gradients.
While cellular respiration releases carbon dioxide into the environment, photosynthesis pulls carbon dioxide out of the atmosphere. The exchange of carbon dioxide and oxygen during photosynthesis (Figure below) and cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels.
Answer:
a. Anaphase 2
b. Metaphase 1
c. Telophase 1
d. Prophase 1
e. Telophase 2
Explanation:
Following is a summary of the events of meiosis:
Interphase:
Prepares the cell for division. Duplication of DNA, duplication of centrioles occurs and the cell grows in size. At this stage the cell is diploid (2n).
Prophase 1:
First stage of Meiosis 1.The centrioles move to the poles of the cell, the nuclear membrane disintegrates, homologous chromosomes pair up (in the form of tetrad), form a chiasmata and then exchange segments of chromosomes with each other. This process is called crossing over.
Metaphase 1:
Involves the arrangement of the crossed over, homologous chromosomes on the metaphase plate which is sort of like a web of spindle fibers that originates from the centrioles.
Anaphase 1:
The tetrads arranged on the metaphase plate are pulled apart by the spindle fibers. This is the result of tension that build up in the spindle fibers as they grow towards opposite poles.
Telophase 1:
The last stage of meiosis 1. Involves the arrival of the chromosomes at the poles, the nuclear membrane starts to form and the chromosomes start decondensing. Telophase 1 yields 2 daughter cells with half the number of chromosomes as that in the parent cell.
Meiosis 2:
Meiosis 2 is exactly similar to mitosis. The only difference is that the haploid cells entering meiosis 2 do not duplicate their DNA. Meiosis 2 just involves the separation of the sister chromatids of homologous chromosomes.
- As mentioned above, interphase does not occur before meiosis 2.
- Prophase 2 involves the disintegration of nuclear envelope, centrosomes start moving to the poles.
- Metaphase 2 arranges the chromosomes on metaphase plate.
- Anaphase 2 separates the sister chromatids from the chromosomes.
- Telophase 2 develops the nuclear envelope and separates the nuclei of the daughter cells into 2. Nuclear division id followed by cytokinesis (division of cytoplasm). Telophase 2 result sin 4 haploid daughter cells with one chromatid from each chromosome.
