Senior one biology examination paper 1000~ 1500 words.

This paper discusses the three forms and functions of life growth from the cellular level, and the important relationship between cell growth and individual life, life (medical) science and biotechnology. Development and growth is the all-round differentiation and growth of germ cells, and its function is to reproduce life, breed individuals and continue species.

Cell growth and development gene

Cells are the basic units of life and life activities. Every living thing is derived from cell growth and differentiation. Cell growth plays an important role in the birth and death of living things, the continuous development of living species and the maintenance of individual life. It is also the foundation of the establishment and application of biological science and technology, which is of great significance. The function of cell growth is briefly described as follows.

1 cell growth form

In life activities, cells have different growth forms, which can be divided into developmental growth, regenerative growth and tumor growth according to the growth results.

1. 1 development and growth is a sexually reproductive organism, which forms fertilized eggs through the combination of hermaphroditic (male and female) germ cells and differentiates into a fetus, and grows into a (sexually) mature individual, which is divided into embryonic development and post-embryonic development.

Embryo development is a process in which fertilized eggs grow and differentiate into fetuses with different tissues and organs, including cleavage stage, blastocyst stage, gastrula stage and organ formation stage [1]. Postembryonic development is the whole process from fetal growth to the end of life (death), including infancy, adolescence, adulthood and old age.

1.2 regenerative growth is the process of regeneration of a certain part of a living body after injury, shedding or amputation, which is divided into physiological regeneration and pathological regeneration.

Physiological regeneration is the replacement and supplement of aging and dead tissues and cells in life activities, such as the replacement of epidermal cells and red blood cells. Pathological regeneration, also known as traumatic regeneration, is the repair or compensation of damaged parts of tissues and organs. According to the ability of regeneration, it can be divided into healing and repairing wounds (called healing) and regenerating missing parts (organs), called regeneration. Its regeneration process includes wound healing, regeneration bud formation, bud growth and differentiation [2].

2. Effects and results of cell growth

2. 1 development, growth, development and growth results The first step is to differentiate a living larva, that is, a fetus, through embryonic development and growth; In the second step, the fetus grows into a reproductive mature individuals, and continues to develop and grow new larvae. At the same time, mature individuals continue to develop, age and die, completing their life cycle.

The role of development and growth is to constantly give birth to individuals and increase the number of groups. Most life groups in nature (including human beings) continue their lives through continuous development and growth, thus achieving eternal life. At the same time, the combination of sexual development and growth is also the main way of biological natural selection, hybrid evolution and individual variation.

2.2 Regenerative growth The role of regenerative growth is to protect individual life and maintain the normal physiological functions required by biological life. Ensure that the larvae (fetuses) are mature and continue to reproduce their lives until the individual life is protected. For example, skin regeneration in physiological regeneration ensures that skin is the first line of defense of the body, prevents external factors from invading the body, and protects internal organs of the body [4]. Red blood cells constantly regenerate, replenish apoptotic red blood cells, and ensure the oxygen supply and carbon dioxide discharge of the body [5]. The regeneration of white blood cells and lymphocytes plays an important role in eliminating harmful substances (germs) invading the body and improving the immunity of the body [5]. Wound healing in injury regeneration plays an indispensable role in timely and effectively preventing harmful substances from entering the body through the wound, ensuring normal blood circulation and preventing massive blood loss from endangering life. Regeneration is of great significance in compensating organs lost due to injury, avoiding disability and restoring functions, such as lizard regenerative tail [2] and salamander regenerative limb [6].

In addition to protecting life, restoring function and escorting individual life, regenerative growth also has the functions of asexual reproduction of life, pure species and reducing variation, such as hydra budding, plant cutting, tissue culture and animal cloning.

3 cell growth conditions

Cell growth needs activation (stimulation, induction) to make cells grow, and growth also needs to be carried out under certain environmental conditions. There are mainly enough nutrients (including oxygen) and suitable temperature and humidity (moisture) for growth.

3. 1 Development, growth, development, growth and cell activation are realized by the combination of two sexes (sperm eggs) to form fertilized eggs [1]. Development and growth are divided into viviparous and oviparous. Viviparous development means that fertilized eggs are carried out in the mother's uterus, and nutrition is provided by the mother through the placenta. The temperature and humidity in the uterus are suitable for development and growth. Oviposition development and growth means that fertilized eggs (in vivo fertilization and in vitro fertilization) cells are carried out outside the mother's body, nutrition is provided by yolk in the egg, and temperature is provided by the outside world. For example, birds hatch eggs, geckos rely on the natural environment temperature (June-September) [7], and the humidity is the moisture in the eggs plus the humidity of the external environment.

3.2 Regenerative growth When tissues and cells of the body are stimulated by injury or normal working cells are lost, regenerative growth cells are activated. Nutrition is supplied by the blood of the body through vascular circulation. The temperature and humidity depend on the environment of the body, and the growth is based on the body. Human beings are social life groups. In today's economic globalization, everyone's life is closely related to society.

In short, human beings should pursue harmony and health while competing for development, pursuing economic interests and possessing wealth. The greatest wealth in life is a healthy and happy life of 65,438+0,000 years old.