Correct Answer: D. Cell walls and turgor pressure

Explanation

The mechanism responsible for providing support in plants is the combination of cell walls and turgor pressure. In plants, the cell walls, composed of cellulose, provide structural support to the cells and tissues. They give rigidity and strength to plant cells, enabling them to maintain their shape and resist external forces. Additionally, turgor pressure, which is the pressure exerted by the cell contents against the cell walls, helps maintain the overall rigidity and upright form of plants.

Correct Answer: C. ammonia

Correct Answer: C) gene

Explanation

The question is asking about the hereditary factor responsible for passing down traits from parents to offspring. The options given are organ, sex, gene, and ovum. The correct answer is option C: gene. Genes are segments of DNA that carry information for specific traits such as eye color or hair texture. They are located on chromosomes within the nucleus of cells. During reproduction, genes from both parents are combined to create a unique set of genes in the offspring. It is important to note that while organs and sex are important factors in reproduction, they are not the hereditary factors responsible for passing down traits. Organs such as the ovaries or testes are responsible for producing the sex cells (ova and sperm) that combine during fertilization to create the offspring, but it is the genes within these cells that determine the traits that are inherited. In summary, the hereditary factor responsible for passing down traits from parents to offspring is the gene. Genes are segments of DNA located on chromosomes and are responsible for coding specific traits. Ova and sperm are produced by organs and combine during fertilization, but it is the genes within these cells that carry the hereditary information.

Correct Answer: A. birds and reptiles

Correct Answer: C. Food predation, disease and accumulation of metabolites

Correct Answer: C. spirogyra

Correct Answer: C) for gaseous exchange

Explanation

Lenticels are small pores found on the surface of stems and roots that allow gases to enter and exit the plant. The function of lenticels is called gaseous exchange, and it helps the plant to obtain the carbon dioxide it needs for photosynthesis and release the oxygen it produces. This process is essential for the plant's survival. Option A is incorrect because lenticels do not receive excess water in the plant. Instead, they allow gases to enter and exit the plant. Option B is also incorrect because lenticels do not absorb water from the atmosphere. They only allow gases to enter and exit the plant. Option D is also incorrect because lenticels do not absorb light. In summary, the function of lenticels is to allow for gaseous exchange, which is important for the survival of the plant. It helps the plant obtain the carbon dioxide it needs for photosynthesis and release the oxygen it produces.

Correct Answer: B. 1/4

Correct Answer: B. parasitic

Explanation

(a)(i) Diagram of human sperm cell

(ii) Sperm cell are produced in the testis(es) seminiferous, tubules and stored temporarily in the epididymis.

(b) The structure of the sperm cell enables it to function effectively in fertilization in the following ways:

(i)Acrosome: This is located at the anterior end of the head which contains lytic enzymes (agents) used to dissolve the egg membrane. it enhances the penetration of the egg during fertilization.

(ii) Middle piece: it contains numerous mitochondria which generate the energy used by the sperm cell to swim towards the egg.

(iii) Long whip-like tail or flagellum:This is found at the posterior end of the sperm cell. It propels or moves the sperm cell.

(iv)The Nucleus: The nucleus in found the head of the sperm cell contains genetic material which fuses with the nucleus of the egg/ovum.

(c) Advantages of sexual reproduction are:

(i) It permits variability of individuals, i.e., new varieties are produced.

(ii) It enhances survival in new or changing environment.

(iii) It allows for the production of hybrids for some desirable traits.

(iv) It provides the means for the maintenance of chromosome number from generation to generation.

(v) It enhances speciation or formation of new species and allows for the continuity of the species.