Reproduction

Step 1: Cross pollination can combine gametes from different plants. Step 2: This forms new genetic combinations. Step 3: In the long term variation can help the population in changing conditions.

Step 1: Pollen from the correct species is needed for successful fertilisation. Step 2: Pollen from another species may not work properly on the stigma. Step 3: The male gamete may not reach the ovule.

Step 1: Ovules become seeds after fertilisation. Step 2: Ovary can become fruit. Step 3: If ovules are not fertilised seeds may be absent.

Step 1: Placenta is the exchange site between mother and embryo. Step 2: Nutrients and oxygen reach the embryo through it. Step 3: Its weakness can affect embryo development.

Step 1: Wastes are also formed by cellular activities in the embryo. Step 2: Placenta helps remove them. Step 3: If wastes are not removed development can be affected.

Step 1: Accurate copying preserves useful traits but reduces variation. Step 2: Small errors can create variation. Step 3: Too many errors can damage essential traits.

Step 1: Asexual offspring are similar to the parent. Step 2: Due to similarity they may share the same weakness. Step 3: A disaster or disease can affect the whole population.

Step 1: Sexual reproduction creates new combinations. Step 2: In changing environments some combinations may be better adapted. Step 3: Therefore variation can help survival.

Step 1: Pollination transfers pollen to the stigma. Step 2: Pollen tube carries male gamete to the ovule. Step 3: Seed forms after fertilisation.

Step 1: First an ovum is released from ovary. Step 2: Fertilisation in the oviduct forms a zygote. Step 3: After division the embryo attaches in the uterus.

Step 1: Reproduction produces new organisms. Step 2: Genetic information passes to offspring. Step 3: Variation especially in sexual reproduction can be useful in changing environments.

Step 1: Gametes have half the chromosome number compared with body cells. Step 2: Male and female gametes fuse during fertilization. Step 3: This fusion restores the normal chromosome number.

Step 1: In asexual reproduction offspring are mostly similar to the parent. Step 2: This can keep variation low in the population. Step 3: If all are similarly weak against a disease, major loss can occur.

Step 1: Some microorganisms form a protective covering in difficult conditions. Step 2: The nucleus may divide many times inside it. Step 3: When conditions become favorable, many offspring may come out.

Step 1: Genetic material controls cell activities. Step 2: Binary fission forms two cells from one cell. Step 3: Without proper division, the new cells may not function normally.

Step 1: Simple wound healing only repairs the damaged part. Step 2: In Planaria, a small piece can develop into a whole organism. Step 3: So it is a stronger example of regeneration.

Step 1: Vegetative propagation is a method of asexual reproduction. Step 2: A new plant forms from parts such as root, stem, or leaf. Step 3: Therefore the new offspring can be very similar to the parent.

Step 1: Seedless plants may be difficult to reproduce by seeds. Step 2: Vegetative propagation forms a new plant from a plant part. Step 3: This method can quickly produce plants with similar traits.

Step 1: In tissue culture, a small plant part is grown on a nutrient medium. Step 2: Microbes can grow quickly in that medium. Step 3: Clean conditions are needed so the plant part grows safely.

Step 1: Rhizopus spores are small and light. Step 2: Air can carry them from one place to another. Step 3: Under suitable conditions, they can form new fungi.