Answer:
Between one-third and one-half of all fertilized eggs never fully implant. A pregnancy is considered to be established only after implantation is complete
Answer:
A. passive transport by diffusion
Explanation:
Diffusion and osmosis are both types of passive transport. They do not require energy. Diffusion is the general term for the process. Osmosis is the diffusion of water molecules.
Many small, uncharged molecules can cross the cell membrane by diffusion. Oxygen and carbon dioxide are examples of two small molecules that pass the cell membrane by passive transport.
Larger or charged molecules require energy to cross the cell membrane. This is achieved by active transport.
The answer would be fossils since they are they remains of past life forms
Answer:
The correct answer will be- Crop rotation
Explanation:
When the growth of a type of crop which uses soil nutrients in abundance and then growing another crop in the same filed led to the decrease in the production of the next crop.
Thus farmers adapted to avoid such farming practices and developed a new practice which allowed the land to become fertile again so that the growth of next crop will not be affected.
The practice involved the planting of a crop on a piece of land then leaving the soil ploughed and unsown for a longer period of time and growing corp on another piece of land allowing the time to restore the nutrient content. This practice is known as "crop rotation".
Thus, crop rotation is the correct answer.
The presence of vertebral column or notochord at any stage of life in any organism is the characteristic of vertebrate.
Explanation:
An animal is vertebrate if it fulfils the following criteria:
Presence of vertebral column or notochord.
Presence of endoskeleton or backbone.
The spinal cord runs above the vertebral column.
Humans embryo has notochord which becomes a vertebral column.
The alimentary canals end in the anus.
Mouth is present ta the anterior side of the vertebrate.
Have legs, fins or wings for movement.
Presence of a nervous system and sensory organs.
Presence of skin, lungs or gills.
Presence of a circulatory system.
Vertebrates include fish, amphibians, reptiles, birds and mammals.
