Answer: The statement is true
Explanation:
Natural selection, as its name implies refers to the choice of certain favorable traits such as resistance to diseases, bigger fruit size etc above lesser favorable traits such as easy susceptibility to diseases, small fruit size etc.
Hence, nature allows the traits that will help living organisms survive best in their environment to be passed down to new offsprings while it eliminates all other traits.
Thus, the statement is true
Answer: A physical change
Explanation: since the melted they are still Crayons. You can freeze it and it would still be a crayon. So it was only a physical change
Answer:
The correct answer is eukaryotes engulfed photosynthesizing prokaryotes
Explanation:
The endosymbiotic theory or symbiogenesis is an evolutionary theory that traces the origin of eukaryotic cells from prokaryotic organisms. It explains that some of the organelles (Mitochondria and Chloroplasts) in eukaryotic cells evolved from free-living prokaryotic microbes which were ingested or engulfed. The ingested prokaryotic cells survived within the organism and developed a symbiotic relationship.
According to the theory, chloroplasts was formed when eukaryotes engulfed photosynthesizing prokaryotes and mitochondria was formed when bacteria capable of aerobic respiration were engulfed.
Answer: Substances that are protein based cannot cross the lipid cell membrane, but can exert their effect by binding to the proteins based receptors present on the lipid bilayer.
Explanation:
Hormones such as calcitonin , Parathyroid hormone and pituatry horomones are proteins and water soluble.They cannot cross lipid bilayer but can bind to ligand binding protein receptors.
These receptors are protein macromolecules that are specific in nature for specific hormones.
After binding to the receptors, these hormone-recpetor complexes activate second messengers and regulate the downstream effects.
