Why do seeds need water to germinate?
(1) Following hydration, enzymes break down stored food and make it available for the embryo.
(2) Water provides energy.
(3) Water activates the chlorophyll molecules so that photosynthesis can begin.
(4) Water dissolves the minerals in the soil so that they become available to the seed.
Plants growing in harsh environments such as deserts, sand dunes, and arctic tundra often reproduce vegetatively. This is because
1. there are few animals available to pollinate them
2. they are members of plants families that only reproduce asexually
3. fruits would freeze or dry out in these environments
4. vegetative reproduction is not as risky as making seeds
Genetic self-incompatibility tends to increase
(1) pollen dispersal
(2) inbreeding
(3) pollination
(4) outcrossing
Which of the following is not a major adaptation that has contributed to the enormous success of angiosperms over all other vascular plants?
1. Seeds
2. Flowers
3. Fruits
4. tracheids
In what percent of angiosperms are the pollen grains shed at three cell stage?
(1) 20
(2) 40
(3) 60
(4) 80
The embryo of a grass seed is enclosed by two protective sheaths, a(n) _________, which covers the young shoot, and a(n) __________, which covers the young root.
1. plumule; radical
2. hypocotyl; picotyls
3. coleoptile; coleorrhiza
4. scutellum; replum
The intine of the pollen grain is a:
1. Thick and discontinuous layer made of sporopollenin
2. Thick and continuous layer made of sporopollenin
3. Thin and discontinuous layer made of cellulose and pectin
4. Thin and continuous layer made of cellulose and pectin
In the monosporic embryo sac of a flowering plant, the number of nuclei that get surrounded by cell walls and thus are organized into cells is:
1. 5
2. 6
3. 7
4. 8
Female flowers remain submerged in water and the pollen grains are released inside the water in:
1. Sea grasses
2. Vallisneria
3. Water lily
4. Water hyacinth
Scientists are trying to transfer apomictic genes into hybrid varieties of several of our food and vegetable crops so that:
1. They get resistance against common pathogens
2. The yield of these plants can be increased many folds
3. Hybrid seeds need not be produced every year
4. Their germplasm is easily stored in labs for further research