Answer:
Scientific models are based on current knowledge, which can limit their effectiveness when new discoveries are made. True
Explanation:
A scientific model can be described as a representation of any scientific topic. The representation may be in the form of a computer simulation, 3 D model, a mathematical equation etc.
The scientific models depict the latest knowledge about a certain topic. With time, as new discoveries are made, the previous scientific theories might be eradicated and new ones might be formed. This will limit the effectiveness of the previous models and new models will have to be made.
The cell membrane is a biological membrane that separates the interior of all cells from the outside environment. It consists of a lipid bilayer with embedded proteins. The basic function of the cell membrane is to protect the cell from its surroundings. The cell membrane controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules. In addition, cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity and cell signalling and serve as the attachment surface for several extracellular structures, including the cell wall, the carbohydrate layer called the glycocalyx, and the intracellular network of protein fibers called the cytoskeleton. In the field of synthetic biology, cell membranes can be artificially reassembled.
Answer:
Answer is option A.
Orchid bees are to Brazil nut trees as breezes are to pine trees.
Explanation:
In Brazil nut trees, the female orchid bees act as pollinators that help in pollination. In pine trees, wind or breeze helps in pollination.
Pine trees are gymnosperms and so they do not have flowers to attract pollinators like bees or butterflies or birds. They are wind-pollinated. Pine trees are monoecious i.e., both male and female reproductive structures (pine cones) are present on the same tree.
The male cones (catkins) produce pollen grains that are lightweight, less sticky and have air bladders or small wing-like structures. As a result of these features, the pollen grains can be easily carried and dispersed by the breeze. In order to prevent self pollination (pollen falling on the female cones of the same tree), the male cones are normally located on the lower branches of the pine tree.
The female cones are located on the upper branches of the tree and the center of the cone contains eggs or ovules. The pollen grains that are carried by the wind, fall on the female cone of another pine tree. Each pollen grain grows a pollen tube into the center of the cone and the nucleus cell of the pollen travels through the tube and reaches the egg, where it combines with the egg to form an embryo. The embryo eventually grows into a seed. The seeds of pine trees are then dispersed by wind or animals such as squirrels.