ABM Grade 12 Modules and activities! 2022-2023

Earth and Life Science part4

Theory of spontaneous generation is similar The creation theory in that its states that living things just suddenly came into existence.

In 1864, the celebrated French chemist Louis Pasteur finally put an end to the Theory of spontaneous generation. He conducted an experiment similar to that by Spallanzani. He put broths in a long swan-necked flask. Then, he boiled the broths to KiIl any microorganisms. He left the flask uncovered for some time and no microorganism appeared. He concluded that the flask with the bent/curved neck filtered the dust particles in the air.

Louis Pasteur discovered that the source of microorganisms for fermentation such as for milk, sugar, and wine was the air.

In the experiments conducted, you found out that living organisms did not spontaneously arise from nonliving matter. Rather, foreign living organisms brought forth the maggots and microorganisms. This is an example of biogenesis.

Biogenesis is the theory that life comes only from pre-existing life and therefore does not explain the origin of life per se. However, biogenesis can explain how life began in a particular place, such as Earth.

Nucleus. This structure is enveloped by a nuclear membrane and contains the DNA and nucleolus. The nuclear membrane has pores that allow the molecules to pass between the nucleus and cytoplasm. The chromosome contains the genes carrying instruction for protein synthesis. The nucleolus is a site for the assembling of ribosomes.

Golgi apparatus. This organelle consists of layered stacks of flattened membranes that process, sort, and deliver proteins. it also packages proteins. Some of these proteins are stored within itself, distributed to other organelles, and secreted outside the cell.

Smooth ER (Endoplasmic Reticulum). This endoplasmic reticulum has no presence of ribosomes on its surface, thus it is called smooth ER. It makes lipids and breaks down drugs and alcohol.

Mitochondrion. This organelle is shaped like a bean and made up of two membranes. The inner membrane is folded and these infoldings are called cristae, which partitions the matrix and the intermembrane space. The mitochondria supply the energy for the cell.

Lysosome. This membrane-bound organelle is basically a specialized vesicle that contains a variety of enzymes. It is used to digest food or break down the cell when the cell dies. It also defends the cell from bacteria and viruses.

Photosynthesis is the process of trapping light energy and converting that energgy to chemical forms that can be utilized for fuel by biological systems. In photosynthesis, light energy causes water and carbon dioxide to synthesize carbohydrates, which store chemical energy, and release oxygen as a waste product.

Photosynthesis involves various stages.

1. The light-dependent reactions

These reactions take place within and across the membrane of the thylakoids, and undergo the following procedures:

a. The capture of light energy from the sun

Lignt energy from the sun is captured by the light-absorbing molecules called chlorophyll. When chlorophyll captures the light energy, the energy transferred to the electrons of chlorophyll molecules make them excited,
and they move to higher energy levels. The electrons then leave the chlorophyll molecules and enter an electron transport chain.

b. The transformation of light energy into chemical energy.

To sum it up, the light-dependent reaction converts light energy to chemical energy in the form of ATP and NADPH to be used in the second stage of photosynthes is the light-independent reaction. Water is broken
down to produce oxygen, electrons and hydrogen ions. Oxygen is given off in the atmosphere.