All questions of Life Processes for Class 10 Exam

Herbivores have the longest small intestine because they digests cellulose

Leech and Earthworm
Leech and earthworm are the two organisms that breathe only through their moist skin. This unique respiratory system is known as cutaneous respiration.

Cutaneous Respiration
Cutaneous respiration is a form of respiration in which gas exchange occurs across the skin or outer integument of an organism. In leeches and earthworms, oxygen and carbon dioxide are exchanged directly through their moist skin.

Mechanism in Leeches and Earthworms
- Leeches have a thin, permeable skin that allows for gas exchange. They absorb oxygen and release carbon dioxide through their skin.
- Earthworms also have a moist skin that helps in the exchange of gases. They breathe through their skin by diffusion.

Importance of Moist Skin
- The presence of moisture on the skin is crucial for cutaneous respiration in leeches and earthworms. It helps in maintaining a suitable environment for gas exchange.
- Dry skin would impede the diffusion of gases, making it difficult for these organisms to breathe solely through their skin.

Adaptations for Cutaneous Respiration
- Both leeches and earthworms have evolved adaptations to facilitate cutaneous respiration. Their thin, moist skin is one such adaptation that allows for efficient gas exchange.
- The surface area of their skin is also maximized to enhance the exchange of gases with the environment.
In conclusion, leeches and earthworms are unique organisms that rely on cutaneous respiration for breathing, utilizing their moist skin to exchange gases with the environment.

Glycolysis:
Glycolysis is the first step in cellular respiration, which is the process by which cells convert glucose into ATP (adenosine triphosphate), the energy currency of the cell. Glycolysis occurs in the cytoplasm of the cell and does not require oxygen.

The End Product of Glycolysis:
The end product of glycolysis is pyruvate. During glycolysis, a molecule of glucose (a 6-carbon sugar) is broken down into two molecules of pyruvate (a 3-carbon compound). This process occurs in a series of enzymatic reactions, which can be divided into two phases: the energy investment phase and the energy payoff phase.

Energy Investment Phase:
In the energy investment phase, two molecules of ATP are used to activate the glucose molecule. This requires the addition of two phosphate groups to the glucose molecule, forming fructose-1,6-bisphosphate. This step ensures that the glucose molecule is primed for further breakdown.

Energy Payoff Phase:
In the energy payoff phase, the fructose-1,6-bisphosphate is broken down into two molecules of glyceraldehyde-3-phosphate (G3P), a 3-carbon compound. Each G3P molecule is then converted into pyruvate through a series of reactions. In this process, several important events occur:

1. Oxidation: Each G3P molecule is oxidized, meaning it loses electrons. This oxidation reaction allows the transfer of high-energy electrons to carrier molecules, such as NAD+ (nicotinamide adenine dinucleotide), which is reduced to NADH. This step is crucial for the production of ATP.

2. Substrate-level phosphorylation: During the conversion of G3P to pyruvate, each molecule of G3P produces 1 molecule of ATP through substrate-level phosphorylation. This process involves the transfer of a phosphate group from a substrate molecule to ADP (adenosine diphosphate), forming ATP.

3. Production of Pyruvate: Finally, each G3P molecule is converted into pyruvate, generating a total of 2 molecules of pyruvate from one glucose molecule.

Overall:
In summary, the end product of glycolysis is pyruvate. Glycolysis is an important metabolic pathway that provides cells with energy in the form of ATP. It is a central process in both aerobic and anaerobic cellular respiration.

Valves prevent the backflow of blood inside the heart during contraction:

The heart is a muscular organ that pumps blood throughout the body. It is made up of four chambers - two atria and two ventricles. During the cardiac cycle, the heart undergoes a series of contractions and relaxations that allow for the efficient circulation of blood.

One of the key functions of the heart is to ensure that blood flows in a unidirectional manner, preventing any backflow. This is achieved through the presence of valves within the heart.

Types of valves:

There are two main types of valves in the heart:

1. Atrioventricular (AV) valves: These valves separate the atria from the ventricles and prevent backflow from the ventricles into the atria. The AV valves consist of the tricuspid valve, which is located between the right atrium and right ventricle, and the mitral valve, which is located between the left atrium and left ventricle.

2. Semilunar valves: These valves separate the ventricles from the major arteries leaving the heart and prevent backflow from the arteries into the ventricles. The semilunar valves consist of the pulmonic valve, which is located between the right ventricle and the pulmonary artery, and the aortic valve, which is located between the left ventricle and the aorta.

How the valves work:

The valves in the heart are flaps of tissue that open and close in response to pressure changes within the heart chambers. When the heart muscle contracts, the pressure within the ventricles increases, causing the AV valves to close. This prevents blood from flowing back into the atria.

At the same time, the increased pressure within the ventricles forces the semilunar valves to open, allowing blood to be pumped out of the heart and into the major arteries. When the heart relaxes, the pressure within the ventricles decreases, causing the semilunar valves to close and prevent backflow of blood from the arteries into the ventricles.

The coordinated opening and closing of the valves ensure that blood flows in a unidirectional manner, from the atria to the ventricles and from the ventricles to the arteries. This mechanism effectively prevents the backflow of blood inside the heart during contraction.