Students who demonstrate understanding can: Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.
Clarification statement: Emphasis is on using models such as Punnett squares, diagrams, and simulations to describe the cause and effect relationship of gene transmission from parent(s) to offspring and resulting genetic variation.
Official wording from the Next Generation Science Standards (NGSS Lead States, 2013). NGSS is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the NGSS were involved in the production of this page, and they do not endorse it. View on nextgenscience.org
Cut a piece off a spider plant and it grows into a new plant that is genetically identical to its parent. A puppy, in contrast, looks a bit like each parent and not exactly like either. The difference lies in how genes are passed on. In asexual reproduction one parent passes on a full copy of its genetic information, so the offspring are clones. In sexual reproduction each parent passes on half of its genetic information, in a sex cell, and the combination is new every time.
Students develop and use models, such as Punnett squares, diagrams and simulations, to explain this cause and effect. A Punnett square shows the possible combinations of alleles (versions of a gene) that offspring can inherit from two parents and the probability of each. For example, two parents that each carry one allele for a hidden trait have a one in four chance of an offspring showing that trait.
Variation matters because it means some offspring may cope better than others if the environment changes, while asexual reproduction is fast and needs only one parent.
Traits are not mixed like paint. Offspring inherit specific alleles from each parent, which is why a child can show a trait neither parent shows.
It shows probabilities. A one in four chance does not mean exactly one of every four offspring will show the trait.
Many plants reproduce asexually too, through runners, bulbs, tubers or cuttings, producing identical offspring.
In pea plants, purple flowers (P) are dominant over white flowers (p). Two parent plants are both Pp. What fraction of their offspring are expected to have white flowers?
Answer: 1/4 (25 percent) of the offspring are expected to have white flowers, and 3/4 purple, showing how sexual reproduction produces variation.
Coin-toss genetics, where each parent's allele is chosen by a coin flip, lets students simulate inheritance and compare their class totals with Punnett square predictions. Contrast this with a cutting from a plant to make the identical-offspring idea concrete.
Assessment asks students to use models to describe cause and effect, so require a short written explanation alongside each Punnett square.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: C) They get all their genetic information from one parent
One parent passes on a full copy of its genetic information, so the offspring are clones.
Answer: B) 1/4
The Punnett square gives PP, Pp, Pp and pp, so 1 of 4 boxes is pp.
Answer: alleles (also accepted: allele)
Alleles are different forms of the same gene, such as P and p.
Answer: D) Offspring have genetic variation
Variation can help some offspring survive changes in the environment.
Answer: C) Asexual reproduction
Runners produce genetically identical new plants from one parent.
Answer: punnett square (also accepted: a punnett square, punnett squares)
A Punnett square shows possible allele combinations and their probabilities.
Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.
Make and defend a claim based on evidence that inheritable genetic variations may result from (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors.
A full lesson with slides, activities and an exit ticket on asexual and sexual reproduction, pitched to grades 6-8 and editable in PowerPoint or Google Slides.
Make a lesson βA printable, differentiated worksheet on MS-LS3-2 with an answer key, ready in about a minute.
Make a worksheet βTurn asexual and sexual reproduction into a quiz students answer online that marks itself, with a class summary for you.
Build a test βThe clarification statement mentions Punnett squares, diagrams and simulations.
Asexual reproduction gives offspring with identical genetic information; sexual reproduction gives offspring with genetic variation.