Question

What do seeds contain? a. male gametophyte and nutritive tissue b. female gametophyte and nutritive tissue c. embryo and nutritive tissue d. mature sporophyte and nutritive tissue

Short answer

The short answer is: Seeds contain the embryo and nutritive tissue (Option c).

Step-by-step solution

Review Terminology

To select the correct answer, let's first review the meaning of the terms in the given options: 1. Male gametophyte: the haploid generation of a plant that produces male sex cells (sperm). 2. Female gametophyte: the haploid generation of a plant that produces female sex cells (egg). 3. Embryo: the young plant enclosed within the seed, developed from the zygote produced after fertilization. 4. Nutritive tissue: the food storage tissue, which provides nutrients for the developing embryo during germination. 5. Mature sporophyte: the diploid, spore-producing generation of a plant.

Analyze each option

Now, let's evaluate each option regarding what seeds contain: a. Male gametophyte and nutritive tissue: Seeds are formed after fertilization, so they no longer contain male gametophytes. b. Female gametophyte and nutritive tissue: After fertilization, the female gametophyte develops into a seed, but it also contains an embryo. c. Embryo and nutritive tissue: This option correctly states the main components of a seed, containing both the young plant (embryo) and the source of nutrients for its development (nutritive tissue). d. Mature sporophyte and nutritive tissue: The seed contains an embryo, which is a part of the sporophyte generation but is not a mature sporophyte.

Choose the correct answer

Based on the analysis, the correct answer is: c. Embryo and nutritive tissue

Key concepts

Gametophyte

Understanding the life cycle of plants involves learning about the gametophyte phase. In the life cycle of most plants, there exist two alternating phases: the sporophyte and the gametophyte. The gametophyte is the sexual phase in the life cycle of a plant. It is characterized by being haploid, which means it contains only one set of chromosomes. During this phase, plants produce gametes – sperm and eggs. Male gametophytes develop male sex cells and female gametophytes produce female sex cells. In many plants, fertilization occurs when a sperm from the male gametophyte fuses with an egg from the female gametophyte, resulting in the formation of a diploid zygote.

Fascinating Fact:

In non-flowering plants such as ferns and mosses, the gametophyte is a free-living organism and can be large and leafy. However, in flowering plants, the gametophytes are reduced in size and are entirely dependent on the parent plant. For example, in angiosperms (flowering plants), the male gametophyte is contained within the pollen grain, while the female gametophyte resides within the ovule.

Embryo Development in Plants

Embryo development is a critical stage in the life cycle of a seed plant. After the male and female gametes unite during fertilization, they form a zygote. This zygote undergoes a series of divisions and transformations in a process known as embryogenesis. Embryogenesis in plants leads to the formation of a multicellular embryo. This embryo is the early developmental stage of a new plant and is the result of mitotic divisions, which increase the number of cells, and subsequent differentiation, where cells take on specific functions.

Stages of Embryo Development:

• Globular stage: The zygote becomes a spherical mass of cells.
• Heart stage: The mass starts to take on a heart-like shape, indicating the beginning of tissue differentiation.
• Torpedo stage: The embryo elongates, and further differentiation occurs, forming the basic structure of the future plant.

The developed embryo has cotyledons, a shoot apex, and a root apex. These are all vital structures for the young plant to begin its life once it emerges from the seed.

Seed Anatomy

Seeds are remarkable structures that serve as the primary means for many plants to disperse their offspring. Within the protective outer coating, known as the seed coat, lie all the necessary components for the development of a new plant. One of the main aspects of a seed is its anatomy, the understanding of which is essential to grasp how plants germinate and grow.

Main Components of a Seed:

• Embryo: The young plant that will develop into the adult plant. It includes embryonic leaves (cotyledons), a shoot tip, and a root tip.
• Endosperm or cotyledon: This is the nutritive tissue mentioned in the exercise. It is a food reserve that nourishes the growing embryo. In monocots, it is known as the endosperm, and in dicots, it's often absorbed into the cotyledons.
• Seed coat: A protective layer that guards the embryo and nutritive tissue from damage and desiccation.

The seed remains in a dormant state until conditions are right for germination. During germination, the seed absorbs water, the seed coat breaks open, and the embryo uses the nutrients to grow and emerge as a seedling.