Answer:
Change in food source.
Explanation:
If there is a change in food source, then the organism will have to adapt to that change. For example, with Darwin's Theory on the finches on the Galapagos Islands. There were many different varieties from different size to different beaks. This was because of changes on food sources and they adapted to obtain them more.
Answer is - planting trees!
Answer:
Once the embryo sac has developed, pollination has occurred, and the pollen tube has grown into the ovary to make contact with the ovule, fertilization (fusion of egg and sperm) can occur.Typically, the pollen tube reaches the embryo sac via the micropyle (Greek, mikros + pyle = small opening), or opening, in the integuments of the ovule.. There, it discharges its sperm into the embry
Explanation:
The pollen tube enters into the ovule, through the micropyle. Inside the embryo sac, the tip of the pollen tube ruptures and the 2 male gametes are set free near the egg apparatus. Inside the embryo sac, one of the 2 male gametes fuses with the egg nucleus and forms a diploid zygote. This process is called syngamy or true fertilisation.
<u>Answer:</u>
C is the answer.
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<u>Explanation:</u>
Organelles (the smallest in this situation) are what you can find inside a cell (example: nucleus, mitochondria, etc..).
Cells are what make up tissues (such as muscles).
Tissues make up organs (such as the heart) and organs make up organ systems (such as the circulatory system).
Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
